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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document And Entity Information
Entity Registrant Name	Retrophin, Inc.
Entity Central Index Key	0001438533
Trading Symbol	rtrx
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		39,692,923
Entity Public Float			$ 661,868,716
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 99,394	$ 41,002
Marketable securities	201,236	214,871
Accounts receivable, net	13,872	18,510
Inventory, net	5,351	2,826
Prepaid expenses and other current assets	3,112	4,831
Prepaid taxes	2,842	3,463
Note receivable, current	0	46,849
Total current assets	325,807	332,352
Property and equipment, net	3,230	2,587
Other assets	5,556	7,364
Intangible assets, net	184,817	182,043
Goodwill	936	936
Total assets	520,346	525,282
Current liabilities:
Accounts payable	18,938	7,522
Accrued expenses	36,018	33,308
Guaranteed minimum royalty, short term	2,000	2,000
Other current liabilities	3,902	1,842
Business combination-related contingent consideration	9,100	16,150
Derivative financial instruments, warrants	15,710	22,440
Total current liabilities	85,668	83,262
Convertible debt	45,077	44,422
Other noncurrent liabilities	2,472	4,010
Guaranteed minimum royalty, long term	13,095	8,068
Business combination-related contingent consideration, less current portion	80,900	71,328
Deferred income tax liability, net	0	6,425
Total liabilities	227,212	217,515
Stockholders' Equity:
Preferred stock $0.001 par value; 20,000,000 shares authorized; 0 issued and outstanding as of December 31, 2017 and 2016, respectively	0	0
Common stock $0.0001 par value; 100,000,000 shares authorized; 39,373,745 and 37,906,669 issued and outstanding as of December 31, 2017 and 2016, respectively	4	4
Additional paid-in capital	471,800	421,309
Accumulated deficit	(177,655)	(113,056)
Accumulated other comprehensive loss	(1,015)	(490)
Total stockholders' equity	293,134	307,767
Total liabilities and stockholders' equity	$ 520,346	$ 525,282

CONSOLIDATED BALANCE SHEETS (Parentheticals) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred Stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	39,373,745	37,906,669
Common stock, shares outstanding (in shares)	39,373,745	37,906,669

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net product sales	$ 154,937	$ 133,591	$ 99,892
Operating expenses:
Cost of goods sold	3,605	4,554	2,185
Research and development	78,168	70,822	50,426
Selling, general and administrative	101,333	91,941	79,541
Change in fair value of contingent consideration	19,389	18,383	13,778
Restructuring	3,608	893	0
Legal fee settlement	2,625	5,212	0
Impairment of intangible assets	0	0	4,710
Total operating expenses	208,728	191,805	150,640
Operating loss	(53,791)	(58,214)	(50,748)
Other Income (expense), net:
Litigation settlement gain	0	0	15,500
Other income (expense), net	1,107	(264)	(296)
Interest expense, net	(1,188)	(759)	(7,748)
Debt early payment penalty	0	0	(2,250)
Loss on extinguishment of debt	0	0	(4,151)
Finance expense	0	0	(600)
Change in fair value of derivative instruments	(4,491)	1,655	(33,307)
Gain on sale of assets	0	0	140,004
Bargain purchase gain	0	0	49,063
Total other income (expense), net	(4,572)	632	156,215
Income (loss) before benefit (provision) for income taxes	(58,363)	(57,582)	105,467
Income tax benefit (provision)	(1,368)	9,679	11,770
Net income (loss)	$ (59,731)	$ (47,903)	$ 117,237
Net income (loss) per common share:
Net income (loss) per common share, basic (in dollars per shares)	$ (1.54)	$ (1.29)	$ 3.49
Net income (loss) per common share, diluted (in dollars per shares)	$ (1.54)	$ (1.29)	$ 3.17
Weighted average common shares outstanding:
Weighted average common shares outstanding, basic (in shares)	38,769,816	36,997,865	33,560,249
Weighted average common shares outstanding, diluted (in shares)	38,769,816	38,288,012	37,581,439
Comprehensive income (loss):
Net income (loss)	$ (59,731)	$ (47,903)	$ 117,237
Foreign currency translation gain (loss)	(339)	93	(40)
Unrealized gain (loss) on sale of marketable securities	(186)	99	(4,927)
Comprehensive income (loss)	$ (60,256)	$ (47,711)	$ 112,270

CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Common Stock in Treasury	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2014		26,428,071	379,591
Beginning balance at Dec. 31, 2014	$ (37,251)	$ 3	$ (3,215)	$ 140,851	$ 4,285	$ (179,175)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based payments	25,900			25,900
Vesting of stock for accrued severance	2,126			2,126
Issuance of common stock, net of fees (in shares)		7,866,000
Issuance of common stock, net of fees	139,987	$ 1		139,986
Exercise of warrants and reclassification of derivative liability (in shares)		870,306
Exercise of warrants and reclassification of derivative liability	28,012			28,012
Retirement of treasury stock (in shares)		379,591	379,591
Retirement of treasury stock	0		$ 3,215			(3,215)
Unrealized gain/(loss) on marketable securities	(4,927)				(4,927)
Foreign currency translation adjustments	(40)				(40)
Option inducement liability reversal and adjustments	3,840			3,840
Issuance of common shares under the equity incentive plan (shares)		1,019,788
Issuance of common shares under the equity incentive plan	6,818			6,818
Shares issued in connection with Cholbam acquisition (in shares)		661,279
Shares issued in connection with Cholbam acquisition	15,844			15,844
Excess tax benefits of stock option exercises	2,425			2,425
Short swing profit judgment offset with settlement expense accrual	0
Net income (loss)	117,237					117,237
Ending balance (in shares) at Dec. 31, 2015		(36,465,853)	0
Ending balance at Dec. 31, 2015	299,971	$ 4	$ 0	365,802	(682)	(65,153)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based payments	29,102			29,102
Exercise of warrants and reclassification of derivative liability (in shares)		898,633
Exercise of warrants and reclassification of derivative liability	20,720			20,720
Unrealized gain/(loss) on marketable securities	99				99
Foreign currency translation adjustments	96			3	93
Issuance of common shares under the equity incentive plan (shares)		542,183
Issuance of common shares under the equity incentive plan	4,016			4,016
Short swing profit judgment offset with settlement expense accrual	2,025			2,025
Tax shortfall from stock option exercises	(359)			(359)
Net income (loss)	(47,903)					(47,903)
Ending balance (in shares) at Dec. 31, 2016		(37,906,669)	0
Ending balance at Dec. 31, 2016	307,767	$ 0	$ 0	421,309	(490)	(113,056)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU 2016-16 required de-recognition of intra-company deferred tax assets	(4,868)					(4,868)
Share based payments	26,645			26,645
Exercise of warrants and reclassification of derivative liability (in shares)		607,481
Exercise of warrants and reclassification of derivative liability	14,866			14,866
Unrealized gain/(loss) on marketable securities	(186)				(186)
Foreign currency translation adjustments	(339)				(339)
Issuance of common shares under the equity incentive plan (shares)		819,573
Issuance of common shares under the equity incentive plan	8,087			8,087
Short swing profit judgment offset with settlement expense accrual	$ 0
ESPP stock purchase and expense (in shares)	40,022
ESPP stock purchase and expense	$ 893			893
Net income (loss)	(59,731)					(59,731)
Ending balance (in shares) at Dec. 31, 2017		(39,373,745)	0
Ending balance at Dec. 31, 2017	$ 293,134	$ 0	$ 0	$ 471,800	$ (1,015)	$ (177,655)

CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) (Parentheticals)	1 Months Ended
	Mar. 31, 2015 USD ($) $ / shares
Statement of Stockholders' Equity [Abstract]
Issuance of common stock, per share amount (in dollars per share) \| $ / shares	$ 19.00
Underwriting fees and other offering costs \| $	$ 9,181,991

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net income (loss)	$ (59,731,000)	$ (47,903,000)	$ 117,237,000
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	17,804,000	16,135,000	13,392,000
Gain upon divestiture of Pediatric Priority Review Voucher	0	0	(140,004,000)
Gain upon divestiture of assets to Turing Pharmaceuticals	0	0	(914,000)
Deferred income tax	(6,425,000)	(22,661,000)	(15,573,000)
Settlement expense	2,625,000	5,212,000	0
Loss on extinguishment of debt	0	0	4,151,000
Impairment of intangible assets	0	0	4,710,000
Derivative financial instruments, warrants, issued, recorded in interest expense	0	0	1,050,000
Accretion on notes receivable	(651,000)	(1,927,000)	(1,267,000)
Accretion on contingent consideration	1,723,000	1,976,000	2,461,000
Amortization of debt discount and deferred financing costs	656,000	656,000	1,340,000
Amortization of premiums on investments	1,338,000	1,097,000	398,000
Share based compensation	26,874,000	29,102,000	25,900,000
Legal accrual reversal	0	(2,967,000)	0
Bargain purchase gain	0	0	(49,063,000)
Change in fair value of contingent consideration	19,389,000	18,383,000	13,778,000
Payments from change in fair value of contingent consideration	(3,949,000)	(4,416,000)	(1,325,000)
Change in estimated fair value of liability classified warrants	4,491,000	(1,655,000)	33,307,000
Foreign currency transaction gain	(1,081,000)	0	0
Other operating activities	526,000	54,000	405,000
Changes in operating assets and liabilities, net of business acquisitions:
Accounts receivable	4,945,000	(6,090,000)	(4,504,000)
Inventory	(1,706,000)	(306,000)	(1,174,000)
Prepaid expenses and other current assets	(2,702,000)	(2,447,000)	(966,000)
Prepaid income taxes	621,000	4,644,000	(8,107,000)
Accounts payable and accrued expenses	2,656,000	9,672,000	3,379,000
Net cash provided by (used in) operating activities	7,403,000	(3,441,000)	(1,389,000)
Cash Flows from Investing Activities:
Purchase of fixed assets	(887,000)	(1,428,000)	(22,000)
Purchase of intangible assets	(13,122,000)	(10,496,000)	(7,008,000)
Security deposits	0	(115,000)	0
Proceeds from the sale/maturity of marketable securities	114,526,000	159,520,000	9,977,000
Purchase of marketable securities	(102,415,000)	(184,111,000)	(198,530,000)
Proceeds from the maturity of notes receivable	47,500,000	47,500,000	0
Cash received upon sale of assets, net	0	0	148,411,000
Cash paid upon acquisition, net of cash acquired	0	(500,000)	(33,430,000)
Net cash provided by (used in) investing activities	45,602,000	10,370,000	(80,602,000)
Cash Flows from Financing Activities:
Payment of acquisition-related contingent consideration	(4,099,000)	(10,511,000)	(3,103,000)
Payment of other liability	(852,000)	(1,000,000)	(2,000,000)
Payment of guaranteed minimum royalty	(2,000,000)	(2,000,000)	(2,000,000)
Proceeds from exercise of warrants	3,645,000	6,005,000	4,475,000
Proceeds from exercise of stock options	8,087,000	4,016,000	6,818,000
Excess tax benefit (shortfall) related to stock compensation	0	(359,000)	2,425,000
Proceeds received from issuance of common stock	0	0	149,487,000
Financing costs from issuance of common stock	0	0	(9,500,000)
Repayment of credit facility	0	0	(45,000,000)
Other financing activities	664,000	0	0
Net cash provided by (used in) financing activities	5,445,000	(3,849,000)	101,602,000
Effect of exchange rate changes on cash	(58,000)	117,000	(10,000)
Net increase in cash and cash equivalents	58,392,000	3,197,000	19,601,000
Cash and cash equivalents, beginning of year	41,002,000	37,805,000	18,204,000
Cash and cash equivalents, end of year	99,394,000	41,002,000	37,805,000
Supplemental Disclosure of Cash Flow Information:
Cash paid for interest	2,070,000	2,070,000	5,838,000
Cash paid for income taxes	7,172,000	7,933,000	9,610,000
Non-cash Investing and financing activities:
Short swing profit judgment offset with settlement expense accrual	0	2,025,000	0
Reclassification of derivative liability to equity due to exercise of warrants	11,221,000	14,715,000	25,537,000
Accrued royalty in excess of minimum payable to the sellers of Thiola	13,247,000	11,206,000	8,219
Accrual of fee to extend term of current Thiola agreement	5,885,000	0	0
Shares issued in connection with Cholbam acquisition	0	0	16,000
Economic Interest - L-UDCA (acquired IPR&D)
Non-cash Investing and financing activities:
Present value of contingent consideration payable	0	25,000,000	0
Cholbam
Non-cash Investing and financing activities:
Present value of contingent consideration payable	$ 0	$ 0	$ 42,000

DESCRIPTION OF BUSINESS

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

DESCRIPTION OF BUSINESS

Organization and Description of Business

Retrophin, Inc. (“we”, “our”, “us”, “Retrophin” and the “Company”) refers to Retrophin, Inc., a Delaware corporation, as well as our direct and indirect subsidiaries. Retrophin is a fully integrated biopharmaceutical company headquartered in San Diego, California focused on the development, acquisition and commercialization of therapies for the treatment of rare diseases. We regularly evaluate and, where appropriate, act on opportunities to expand our product pipeline through licenses and acquisitions of products in areas that will serve patients with rare diseases and that we believe offer attractive growth characteristics.

The Company is developing the following pipeline products:

The Company is developing fosmetpantotenate (RE-024), a novel small molecule, as a potential treatment for PKAN. PKAN is a genetic neurodegenerative disorder that is typically diagnosed in the first decade of life. Consequences of PKAN include dystonia, dysarthria, rigidity, retinal degeneration, and severe digestive problems. There are currently no viable treatment options for patients with PKAN. Fosmetpantotenate is a phosphopantothenate replacement therapy that aims to restore levels of this key substrate in PKAN patients.

Sparsentan (RE-021) is an investigational product candidate which acts as both a potent ARB, as well as a selective ERA, with in vitro selectivity toward endothelin receptor type A. The Company secured a license to sparsentan from Ligand Pharmaceuticals, Inc. and Bristol-Myers Squibb Company (who referred to it as DARA). The Company is developing sparsentan as a treatment for FSGS, which is a leading cause of end-stage renal disease and nephrotic syndrome (“NS”). There are no U.S. Food and Drug Administration (the "FDA") approved treatments for FSGS and off-label resources are limited to ACE/ARBs, steroids, and immunosuppressant agents, which are effective in only a subset of patients.

The Company recently announced the exploration of a second indication, IgAN, for sparsentan. IgAN is characterized by hematuria, proteinuria, and variable rates of progressive renal failure. There is no FDA approved treatment for IgAN.

The Company is a party to a joint development agreement with Censa Pharmaceuticals Inc., a privately held biotechnology company focused on developing therapies for orphan metabolic diseases, to evaluate sepiapterin ("CNSA-001") for the treatment of phenylketonuria (PKU). CNSA-001 is an orally bioavailable form of a natural precursor of tetrahydrobiopterin (BH4) with the potential to provide improved phenylalanine (Phe) reduction in patients with PKU when compared to BH4.

PKU is a rare, genetic metabolic condition in which the body cannot breakdown Phe due to a missing or defective phenylalanine hydroxylase (PAH) enzyme. High Phe levels can lead to developmental and physical growth delay, executive function impairment, seizures, and microcephaly caused by toxic Phe accumulation in the brain.

In September 2017, the Company entered a three-way Cooperative Research and Development Agreement ("CRADA") with the National Institutes of Health’s National Center for Advancing Translational Sciences (NCATS) and patient advocacy foundation NGLY1.org to collaborate on research efforts aimed at the identification of potential small molecule therapeutics for NGLY1 deficiency.

N-glycanase deficiency, or NGLY1 deficiency, is an extremely rare genetic disorder believed to be caused by a deficiency in an enzyme called N-glycanase-1, which is encoded by the gene NGLY1. The condition has been characterized by symptoms such as developmental delays, seizures, complex hyperkinetic movement disorders, diminished reflexes and an inability to produce tears. There are no approved therapeutic options for NGLY1 deficiency, and current therapeutic strategies are limited to symptom management.

Liquid ursodeoxycholic acid ("L-UDCA") is a liquid formulation of ursodeoxycholic acid being developed for the treatment of a rare liver disease called primary biliary cholangitis ("PBC"). The Company obtained the rights to L-UDCA during 2016 with the intention of making L-UDCA commercially available to the subset of PBC patients who have difficulty swallowing.

The Company sells the following three products:


•	Chenodal (chenodiol tablets) is approved in the United States for the treatment of patients suffering from gallstones in whom surgery poses an unacceptable health risk due to disease or advanced age. Chenodal has been the standard of care for cerebrotendinous xanthomatosis ("CTX") patients for more than three decades and the Company is currently pursuing adding this indication to the label.


•	Cholbam (cholic acid capsules) is approved in the United States for the treatment of bile acid synthesis disorders due to single enzyme defects and is further indicated for adjunctive treatment of patients with peroxisomal disorders.


•	Thiola (tiopronin tablets) is approved in the United States for the prevention of cystine (kidney) stone formation in patients with severe homozygous cystinuria.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

A summary of the significant accounting policies applied in the preparation of the accompanying consolidated financial statements follows:

Principles of Consolidation

The consolidated financial statements represent the consolidation of the accounts of the Company and its subsidiaries in conformity with accounting principles generally accepted in the United States ("U.S. GAAP"). All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

In preparing financial statements in conformity with U.S. GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in these estimates. On an ongoing basis, the Company evaluates its estimates and assumptions. These estimates and assumptions include revenue recognition, valuing equity securities in share-based payments, estimating expenses of contracted research organizations, estimating fair value of equity instruments recorded as derivative liabilities, estimating the fair value of net assets acquired in business combinations, estimating the useful lives of depreciable and amortizable assets, goodwill impairment, estimating the fair value of contingent consideration, estimating of valuation allowances and uncertain tax positions, and estimates associated with the assessment of impairment for long lived assets.

Revenue Recognition

Product sales for the year ended December 31, 2017 and 2016 consisted of sales of Chenodal, Cholbam and Thiola. Product sales for the year ended December 31, 2015 consisted of sales of Chenodal, Thiola and Vecamyl (divested in 2015). Revenue from product sales is recognized when persuasive evidence of an arrangement exists, title to product and associated risk of loss have passed to the customer, the price is fixed or determinable, collection from the customer is reasonably assured, the Company has no further performance obligations, and returns can be reasonably estimated. The Company sells in the United States and Canada through a direct-to-patient distributor. Under this distribution model, the Company records revenues when customers take title of the product.

The Company sells Kolbam internationally, and these revenues are immaterial when taken in consideration of the financial statements as a whole.

Revenue from product sales is recorded net of applicable provisions for rebates under government (including medicaid) programs, commercial rebates, prompt pay discounts, and other sales-related deductions. We review our estimates of rebates and other applicable provisions each period and record any necessary adjustments in the current period.

Deductions from Revenue

Government Rebates: The Company estimates the rebates that we will be obligated to provide to government programs and deducts these estimated amounts from our gross product sales at the time the revenues are recognized. Allowances for government rebates and discounts are established based on actual payer information, which is reasonably estimated at the time of delivery, and the government-mandated discounts applicable to government-funded programs. Rebate discounts are included in other current liabilities in the accompanying consolidated balance sheets.

Commercial Rebates: The Company estimates the rebates that we incur due to contracts with certain commercial payors and deducts these estimated amounts from our gross product sales at the time the revenues are recognized. Allowances for commercial rebates are established based on actual payer information, which is reasonably estimated at the time of delivery. Rebate discounts are included in other current liabilities in the accompanying consolidated balance sheets.

Prompt Pay Discounts: The Company offers discounts to certain customers for prompt payments. The Company accrues for the estimated prompt pay discount based on the gross amount of each invoice for those customers at the time of sale.

Product Returns: Consistent with industry practice, the Company offers its customers a limited right to return product purchased directly from the Company, which is principally based upon the product’s expiration date. Generally, shipments are only made upon a patient prescription thus returns are minimal.

Research and Development Costs

Research and development includes expenses related to sparsentan, fosmetpantotenate and our other pipeline programs. We expense all research and development costs as they are incurred. Our research and development costs are comprised of salaries and bonuses, benefits, non-cash share based compensation, license fees, milestones under license agreements, costs paid to third-party contractors to perform research, conduct clinical trials, and develop drug materials and delivery devices, and associated overhead expenses and facilities costs. Reimbursed research and development costs under collaborative arrangements are recorded as a reduction to research and development costs. We charge direct internal and external program costs to the respective development programs. We also incur indirect costs that are not allocated to specific programs because such costs benefit multiple development programs and allow us to increase our pharmaceutical development capabilities. These consist of internal shared resources related to the development and maintenance of systems and processes applicable to all of our programs. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors, and clinical research organizations (“CRO’s"). Invoicing from third-party contractors for services performed can lag several months. We accrue the costs of services rendered in connection with third-party contractor activities based on our estimate of management fees, and costs associated with site monitoring and data management.

Employee Stock-Based Compensation

The Company recognizes all employee share-based compensation as a cost in the financial statements. Equity-classified awards principally related to stock options, restricted stock units (“RSUs”) and performance stock units ("PSUs"), are measured at the grant date fair value of the award. The Company determines grant date fair value of stock option awards using the Black-Scholes option-pricing model. The fair value of RSUs are determined using the closing price of the Company’s common stock on the grant date. For service based vesting grants, expense is recognized over the requisite service period based on the number of options or shares expected to ultimately vest. For PSUs, expense is recognized over the implicit service period, assuming vesting is probable. No expense is recognized for PSUs if it is not probable the vesting criteria will be satisfied. Forfeitures are accounted for as they occur.



	Initial Vesting Term
Stock Options	3 to 4 years
Restricted Stock Units	2 to 3 years

Earnings (Loss) Per Share

We calculate our basic earnings per share by dividing net income by the weighted average number of shares outstanding during the period. The diluted earnings per share computation includes the effect, if any, of shares that would be issuable upon the exercise of outstanding stock options, derivative liability, convertible debt and RSUs, reduced by the number of shares which are assumed to be purchased by the Company from the resulting proceeds at the average market price during the year, when such amounts are dilutive to the earnings per share calculation.

Cash and Cash Equivalents

We consider all highly liquid marketable securities with an original maturity of three months or less to be cash equivalents. Due to the short-term maturity of such investments, the carrying amounts are a reasonable estimate of fair value.

Marketable Securities

The Company accounts for marketable securities held as “available-for-sale” in accordance with ASC 320, “Investments Debt and Equity Securities” (“ASC 320”). The Company classifies these investments as current assets and carries them at fair value. Unrealized gains and losses are recorded as a separate component of stockholders’ equity as accumulated other comprehensive loss. Realized gains or losses on marketable security transactions are reported in the Consolidated Statements of Operations and Comprehensive Income (Loss). Marketable securities are maintained at one financial institution and are governed by the Company’s investment policy as approved by our Board of Directors.

Trade and Notes Receivable

Trade Receivables, Net

Trade accounts receivable are recorded net of allowances for prompt payment and doubtful accounts. Estimates for allowances for doubtful accounts are determined based on existing contractual obligations, historical payment patterns and individual customer circumstances. The allowance for doubtful accounts was $0.2 million and $0.3 million at December 31, 2017 and 2016, respectively. For the years ended December 31, 2017, 2016 and 2015, bad debt expense recorded in the Statement of Operations and Comprehensive Income (Loss) was approximately $0.2 million, $0.2 million and none, respectively.

Notes Receivable

Notes receivable arose from the sale of a pediatric priority review voucher (the "PRV"). On July 2, 2015, the Company sold and transferred the PRV to Sanofi for $245.0 million. $150.0 million was received upon closing, and $47.5 million was due on each of the first and second anniversaries of the closing. In accordance with U.S. GAAP, the Company recorded the future short term and long term notes receivable at their present value of $46.2 million and $44.9 million, respectively, at the date of the sale using a discount rate of 2.8%. The accretion on the notes receivables totaled $0.7 million and$1.9 million for 2017 and 2016, respectively, and is recorded in interest expense, net, in the Consolidated Statements of Operations and Comprehensive Income (Loss). The first and second annual payments were received on July 1, 2016 and June 30, 2017 in accordance with the terms of the sale agreement. As of December 31, 2017, there are no outstanding notes receivable.

Inventory and Related Reserves

Inventory, which is recorded at the lower of cost or net realizable value, includes materials, labor, and other direct and indirect costs and are valued using the first-in, first-out method. The Company periodically analyzes its inventory levels to identify inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value, and writes down such inventory as appropriate. In addition, the Company's products are subject to strict quality control and monitoring which the Company’s manufacturers perform throughout their manufacturing process. The Company does not directly manufacture any product. The Company has single suppliers for products Chenodal and Thiola, and prospectively arranges for manufacture from contract service providers for its product Cholbam. The inventory reserve was $0.7 million and $0.6 million at December 31, 2017 and 2016, respectively.

Inventory, net of reserve, consisted of the following at December 31, 2017 and 2016 (in thousands):



	December 31, 2017		December 31, 2016
Raw material	$	3,435	$	1,336
Finished goods	1,916		1,490
Total inventory	$	5,351	$	2,826

Segment Information

The Company currently operates in one business segment focused on the development and commercialization of innovative therapies for people with serious and life threatening rare diseases and medical conditions. The Company is not organized by market and is managed and operated as one business. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate products, other than revenues, and does not have separately reportable segments.

Property and Equipment, net

Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over the related estimated useful lives as presented in the table below. Significant additions and improvements are capitalized, while repairs and maintenance are charged to expense as incurred. Property and equipment purchased for specific research and development projects with no alternative use is expensed as incurred.

The major classifications of property and equipment, including their respective expected useful lives, consists of the following:



Computers and equipment	3 years
Furniture and fixtures	7 years
Leasehold improvements	Shorter of length of lease or life of the asset

Intangible Assets, Net

Our intangible assets consist of licenses, purchased technology and acquired in-process research and development (IPR&D). Intangible assets with definite lives are amortized on a straight-line basis over their estimated useful lives and are reviewed periodically for impairment.

Intangible assets related to IPR&D projects are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. During the period the assets are considered indefinite-lived, they will not be amortized but will be tested for impairment. If and when development is complete, which generally occurs when regulatory approval to market a product is obtained, the associated assets are deemed finite-lived and are amortized over a period that best reflects the economic benefits provided by these assets.

Goodwill

Goodwill represents the excess of purchase price over fair value of net assets acquired in a business combination and is not amortized. Goodwill is subject to impairment testing at least annually or when a triggering event occurs that could indicate a potential impairment. The Company has one segment and one reporting unit and as such reviews goodwill for impairment at the consolidated level.

For the years ended December 31, 2017, 2016 and 2015 there were no impairments to goodwill.

Impairment of Long-Lived Assets

Our long-lived assets are primarily comprised of intangible assets and property and equipment. We evaluate our finite-lived intangible assets, other than goodwill and property and equipment, for impairment whenever events or changes in circumstances indicate the carrying value of an asset or group of assets may not be recoverable. If these circumstances exist, recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset group to future undiscounted net cash flows expected to be generated by the use and eventual disposition of the asset group. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets.

In addition, indefinite-lived intangible assets, comprised of IPR&D, are reviewed for impairment annually and whenever events or changes in circumstances indicate that it is more likely than not that the asset is impaired by comparing the fair value to the carrying value of the asset. To determine the fair value of the asset, the Company used the multi-period excess earnings method of the income approach.

For the year ended December 31, 2015 the Company wrote off the intangible asset related to Carbetocin and recorded a loss of $4.7 million. There were no impairments related to intangible assets in the years ended December 31, 2017 or 2016.

Contingent Consideration

We record contingent consideration resulting from a business combination at its fair value on the acquisition date. On a quarterly basis, we revalue these obligations and record increases or decreases from their fair value as an adjustment to the consolidated statement of operations. Changes to contingent consideration obligations can result from changes to discount rates, accretion of the liability due to the passage of time, changes in revenue forecasts and changes in our estimates of the likelihood or timing of achieving commercial milestones.

Income Taxes

The Company follows ASC 740, Income Taxes, which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are based on the differences between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance to the extent management concludes it is more likely than not that the asset will not be realized.

The standard addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the financial statements. Under ASC 740, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the tax authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. ASC 740 also provides guidance on de-recognition, classification, interest and penalties on income taxes, accounting in interim periods and requires increased disclosures. The Company’s policy is to record estimated interest and penalty related to the underpayment of income taxes or unrecognized tax benefits as a component of its income tax provision.

Reclassifications

Certain reclassifications have been made to the prior year financial statements in order to conform to the current year’s presentation.

Patents

The Company expenses external costs, such as filing fees and associated attorney fees, incurred to obtain issued patents and patent applications pending. The Company also expenses costs associated with maintaining and defending patents subsequent to their issuance in the period incurred.

Derivative Financial Instruments, Warrants

The Company does not use derivative instruments to hedge exposures to cash flow, market or foreign currency risks. However, certain warrants to purchase common stock that do not meet the requirements for classification as equity, in accordance with the Derivatives and Hedging Topic of the ASC, are classified as liabilities. The Company’s warrants are classified as liability instruments due to an anti-dilution provision that provides for a reduction to the exercise price of the warrants if the Company issues additional equity or equity linked instruments in the future at an effective price per share less than the exercise price then in effect. The derivative instrument was initially recorded at its fair value and is then revalued at each reporting date, with changes in the fair value reported in the Consolidated Statements of Operations and Comprehensive Income (Loss).

Treasury Stock

The Company records treasury stock at the cost to acquire it and includes treasury stock as a component of stockholders’ equity until it is retired. As of December 31, 2017 the Company has no treasury stock.

Recently Adopted Accounting Pronouncements

In April 2016, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation —Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Specifically, the ASU requires all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) to be recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur. An entity also should recognize excess tax benefits, and assess the need for a valuation allowance, regardless of whether the benefit reduces taxes payable in the current period. That is, off balance sheet accounting for net operating losses stemming from excess tax benefits would no longer be required and instead such net operating losses would be recognized when they arise. Existing net operating losses that are currently tracked off balance sheet would be recognized, net of a valuation allowance if required, through an adjustment to opening retained earnings in the period of adoption. Entities will no longer need to maintain and track an “APIC pool.” The ASU also requires excess tax benefits to be classified along with other income tax cash flows as an operating activity in the statement of cash flows. In addition, the ASU elevates the statutory tax withholding threshold to qualify for equity classification up to the maximum statutory tax rates in the applicable jurisdiction(s). The ASU also clarifies that cash paid by an employer when directly withholding shares for tax withholding purposes should be classified as a financing activity. The ASU provides an optional accounting policy election (with limited exceptions), to be applied on an entity-wide basis, to either estimate the number of awards that are expected to vest (consistent with GAAP) or account for forfeitures when they occur. Upon adoption, all of the tax effects related to share-based payments at settlement (or expiration) will be recorded through the income statement. The Company adopted this ASU as of January 1, 2017 using a prospective transition method related to the presentation of excess tax benefits on the statement of cash flows. In 2016 and 2015, the Company would have recorded a tax expense of $0.4 million and a tax benefit of $2.4 million, respectively.

In August 2016, the FASB issued ASU No. 2016-15,Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. These amendments provide cash flow statement classification guidance for: 1. Debt Prepayment or Debt Extinguishment Costs; 2. Settlement of Zero-Coupon Debt Instruments or Other Debt Instruments with Coupon Interest Rates That Are Insignificant in Relation to the Effective Interest Rate of the Borrowing; 3. Contingent Consideration Payments Made after a Business Combination; 4. Proceeds from the Settlement of Insurance Claims; 5. Proceeds from the Settlement of Corporate-Owned Life Insurance Policies, including Bank-Owned Life Insurance Policies; 6. Distributions Received from Equity Method Investees; 7. Beneficial Interests in Securitization Transactions; and 8. Separately Identifiable Cash Flows and Application of the Predominance Principle. This ASU became effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company has elected to adopt this guidance in the fourth quarter of year ended December 31, 2017, which applied retrospectively, reclassifies portions of payments made for contingent consideration in the financing section to the operation section of the Consolidated Statements of Cash Flows. The reclassification on the Consolidated Statements of Cash Flows was $1.9 million and $0.8 million for 2016 and 2015, respectively.

In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The new guidance changes the accounting for income tax effects of intra-entity transfers of assets other than inventory. Under the new guidance, the selling (transferring) entity is required to recognize a current tax expense or benefit upon transfer of the asset. Similarly, the purchasing (receiving) entity is required to recognize a deferred tax asset or deferred tax liability, as well as the related deferred tax benefit or expense, upon receipt of the asset. As of January 1, 2017, the Company reversed the balance of $4.9 million in its prepaid tax asset account as a charge to retained earnings.

Recently Issued Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position or results of operations upon adoption.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. Under the new standard, revenue is recognized at the time a good or service is transferred to a customer for the amount of consideration for which the entity expects to be entitled for that specific good or service. Entities may use a full retrospective approach or report the cumulative effect as of the date of adoption. The Company adopted the new standard on January 1, 2018 using the full retrospective approach and does not expect any impact on the timing or recognition of revenue because its only revenue source is product sales and because no variable consideration exists. The new standard also requires enhanced disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. The Company expects to make these disclosures in its financial statements for the period ending March 31, 2018.

In February 2016, the FASB issued ASU No. 2016-02, Leases. The new standard establishes a right-of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The Company is in the process of evaluating the impact of this guidance on its consolidated financial statements and related disclosures; however, based on the Company's current operating leases, it is expected to have a material impact to the consolidated balance sheet by increasing assets and liabilities.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Topic 326 amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, Topic 326 eliminates the probable initial recognition threshold in current GAAP and, instead, requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. For available for sale debt securities, credit losses should be measured in a manner similar to current GAAP, however Topic 326 will require that credit losses be presented as an allowance rather than as a write-down. This ASU update affects entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. This update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. As of December 31, 2017, the Company holds $201.2 million in available for sale debt securities that are affected by this ASU. If adopted as of December 31, 2017, this would not have a material impact on financial statements.

In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The new guidance dictates that, when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, it should be treated as an acquisition or disposal of an asset. The guidance will be effective for the fiscal year beginning on January 1, 2018, including interim periods within that year (early adoption is permitted). The Company is currently evaluating the potential effect of the guidance on its consolidated financial statements.

In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features. These amendments simplify the accounting for certain financial instruments with down round features. The amendments require companies to disregard the down round feature when assessing whether the instrument is indexed to its own stock, for purposes of determining liability or equity classification. Companies that provide earnings per share ("EPS") data will adjust their basic EPS calculation for the effect of the feature when triggered (i.e., when the exercise price of the related equity-linked financial instrument is adjusted downward because of the down round feature) and will also recognize the effect of the trigger within equity. As of and for the year ended December 31, 2017, the Company had warrants with down round features with a fair value of $15.7 million on the Consolidated Balance Sheet and recorded $19.4 million to Consolidated Statement of Operations and Comprehensive Income (Loss). The Company will adopt this ASU as of January 1, 2018.

In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The new guidance addresses a specific consequence of the Tax Act. This accounting update allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Act. The amendments eliminate the stranded tax effects that were created as a result of the reduction of historical U.S. federal corporate income tax rate to the newly enacted U.S. federal corporate income tax rate. The accounting update is effective January 1, 2019, with early adoption permitted, and is to be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. The Company is currently evaluating the potential effect of the guidance on its consolidated financial statements.

BUSINESS COMBINATION AND ASSET TRANSACTIONS

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

BUSINESS COMBINATION AND ASSET TRANSACTIONS

Amendment to Trademark License and Supply Agreement

On November 3, 2017, the Company amended their agreement with the manufacturer of Thiola to extend the term of the current exclusive U.S. and Canada licensing agreement by an additional five years, to 2029. The royalty rate and guaranteed minimum payment were also extended through the new agreement term. Upon execution of the amendment, the Company capitalized an additional $5.9 million in intangible assets and recorded a guaranteed minimum liability for the same amount.

Acquisition of Liquid Ursodeoxycholic Acid (L-UDCA)

On June 20, 2016, the Company signed a definitive agreement to purchase the rights, titles, licenses and ownership of L-UDCA from Asklepion Pharmaceuticals, LLC ("Asklepion").

The acquisition was accounted for under the acquisition method of accounting in accordance with Accounting Standard Codification ("ASC") 805. The fair value of assets acquired and liabilities assumed was based upon an independent third-party valuation and the Company’s estimates. Critical estimates in valuing certain intangible assets include but are not limited to future expected cash flows from acquired product rights for L-UDCA, licenses, trade names and developed technologies, present value and discount rates. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates.

The purchase included $25.5 million for an intangible asset with a definite life related to product rights in the U.S. The useful life related to the acquired product rights is expected to be approximately 17 years once the NDA is approved by the FDA. Until approval, the asset is considered IPR&D with an indefinite life and is not amortized.

The contingent consideration of $25.0 million (present value) recorded during the period ended June 30, 2016, is related to an agreement to pay an additional cash amount in the form of milestones and sales royalties through 2035. The accrued contingent consideration was recorded as a liability at acquisition-date fair value using the income approach with an assumed discount rate of 12.0% over the applicable term. The undiscounted amount the Company could pay as contingent consideration under the agreement is up to $70.3 million.

The purchase price allocation of $25.5 million as of the acquisition completion date of June 16, 2016 was as follows (in thousands):



Cash paid upon consummation	$	500
Present value of contingent consideration	25,000
Total purchase price	$	25,500
Fair Value of Assets Acquired and Liabilities Assumed
Acquired product rights: L-UDCA (intangible asset)	$	25,500
Total purchase price	$	25,500

Unaudited pro forma information for the transaction is not presented, because the effects of such transaction are considered immaterial to the Company.

Acquisition of Cholbam (cholic acid)

On January 12, 2015, the Company signed a definitive agreement under which it acquired the exclusive right to purchase from Asklepion, all worldwide rights, titles, and ownership of Cholbam (cholic acid) for the treatment of bile acid synthesis disorders, if approved by the FDA. Under the terms of the agreement, the Company paid Asklepion an upfront payment of $5.0 million and agreed to pay milestones based on FDA approval and net product sales, plus tiered royalties on future net sales of Cholbam.

On March 18, 2015, the FDA approved Cholbam capsules, the first FDA approved treatment for pediatric and adult patients with bile acid synthesis disorders due to single enzyme defects, and for patients with peroxisomal disorders (including Zellweger spectrum disorders). As a result of the approval, the Company exercised its right to purchase from Asklepion all worldwide rights, titles, and ownership of Cholbam and related assets. The FDA also granted Asklepion a Rare Pediatric Disease Priority Review Voucher ("Pediatric PRV"), awarded to encourage development of new drugs and biologics for the prevention and treatment of rare pediatric diseases. A Pediatric PRV is transferable and provides the bearer with FDA priority review classification for a new drug application. The Pediatric PRV was transferred to Retrophin under the original terms of the agreement with Asklepion.

On March 31, 2015, the Company completed its acquisition from Asklepion of all worldwide rights, titles and ownership of Cholbam, including all related contracts, data assets, intellectual property, regulatory assets and the Pediatric PRV, in exchange for a cash payment of $28.4 million, in addition to approximately 661,279 shares of the Company’s common stock (initially valued at $9 million at the time of the definitive agreement with Asklepion, and $15.8 million at the acquisition completion date). The Company is also required to pay contingent consideration consisting of milestones and tiered royalties with a present value of $39.1 million.

The original asset value of the Pediatric PRV was recognized at $96.3 million. In this valuation process, we considered various factors which included data from recent sales of similar vouchers. The consideration paid to Asklepion did not value the Pediatric PRV because the issuance of a Pediatric PRV is extremely rare. Therefore when the FDA granted the Pediatric PRV with the Cholbam approval, a bargain purchase gain resulted.

The acquisition was accounted for under the acquisition method of accounting in accordance with ASC 805. The fair value of assets acquired and liabilities assumed was based upon an independent third-party valuation and the Company’s estimates. Critical estimates in valuing certain intangible assets include but are not limited to future expected cash flows from acquired product rights-Cholbam, Pediatric PRV, trade names and developed technologies, present value and discount rates. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates.

The purchase included $83.2 million of intangible assets with definite lives related to product rights with values of $75.9 million for the U.S. and $7.3 million for the international rights. The useful lives related to the acquired product rights are expected to be approximately 10 years.

The contingent consideration of $39.1 million recorded during the year ended December 31, 2015 is related to an agreement to pay an additional cash amount based on the product performance through 2025. The accrued contingent consideration was recorded as a liability at acquisition-date fair value using the income approach with assumed discount rates of 19.0% over the applicable term. The undiscounted amount the Company could pay as contingent consideration under the agreement is up to $78.4 million.

Service fees with a net present value of $2.9 million were recorded during the year ended December 31, 2015. The net present value is based upon $4.0 million in total payments over a four year period starting as of the acquisition date.

As part of the business combination the Company recorded a deferred tax liability of $39.9 million. The deferred tax liability is derived from the difference in the Company's book basis and tax basis in the assets acquired of $88.5 million. Our tax rate utilized is 45.4%.

The purchase price allocation of $91.3 million as of the acquisition completion date of March 31, 2015 was as follows (in thousands):



Cash paid upon consummation	$	33,430
Present value of contingent consideration and service fees	42,010
Fair Value of 661,279 shares issued to Asklepion	15,844
Total Purchase Price	$	91,284
Fair Value of Assets Acquired and Liabilities Assumed
Acquired product rights-Cholbam (Intangible Asset)	$	83,200
Pediatric Priority Review Voucher	96,250
Inventory	777
Deferred tax liability	(39,880		)
Total Allocation of Purchase Price	140,347
Bargain Purchase Gain	(49,063		)
Total Purchase Price	$	91,284

Divestiture of Assets:

Sale of Assets to Sanofi

The FDA granted Asklepion a Pediatric PRV, awarded to encourage development of new drugs and biologics for the prevention and treatment of rare pediatric diseases. A Pediatric PRV is transferable and provides the bearer with FDA priority review classification for a new drug application. The Pediatric PRV was transferred to the Company under the terms of the asset purchase agreement between the Company and Asklepion dated January 12, 2015, pursuant to which the Company acquired Cholbam.

On July 2, 2015, the Company sold and transferred the Pediatric PRV to Sanofi for $245.0 million. $150.0 million was received upon closing, and $47.5 million was due on each of the first and second anniversaries of the closing. In accordance with U.S. GAAP, the Company recorded the future short term and long term notes receivable at their present value of $46.2 million and $44.9 million, respectively, at the date of the sale using a discount rate of 2.8%. The gain from the sale of the asset was approximately $140.0 million, net of $4.9 million in fees contractually due as part of the Cholbam acquisition. The first and second annual payments were received on July 1, 2016 and June 30, 2017 in accordance with the terms of the sale agreement.

Sale of Assets to Turing Pharmaceuticals

On October 13, 2014, the Company entered into a binding Summary Separation Proposal with its then-current Chief Executive Officer. Among other things, the Summary Separation Proposal set forth the terms for the sale of the Company’s Vecamyl, Syntocinon and ketamine licenses and assets to Turing Pharmaceuticals, a company controlled by the former Chief Executive Officer.

On January 9, 2015, the Company entered into a purchase agreement with Turing Pharmaceuticals pursuant to which the Company sold Turing Pharmaceuticals its ketamine licenses and assets ("Assets") for a purchase price of $1.0 million, and pursuant to which Turing Pharmaceuticals also assumed all future liabilities related to the Assets.

On February 13, 2015, Retrophin, Inc., its wholly-owned subsidiary Manchester and its other wholly-owned subsidiary Retrophin Therapeutics International, LLC (collectively, the "Sellers") entered into a purchase agreement with Waldun Pharmaceuticals, LLC ("Waldun"), pursuant to which the Sellers sold Waldun the product rights to mecamylamine hydrochloride ("Vecamyl Product Rights") for a purchase price of $0.7 million. Waldun in turn sold the Vecamyl Product Rights to Turing Pharmaceuticals. In connection therewith, on February 13, 2015, the Company, together with Manchester, entered into an asset purchase agreement with Turing Pharmaceuticals, pursuant to which the Company sold Turing Pharmaceuticals their mecamylamine hydrochloride inventory ("Inventory") for a purchase price of $0.3 million. Turing Pharmaceuticals also assumed certain liabilities related to the Vecamyl Product Rights and the Inventory.

On February 13, 2015, the Company entered into an asset purchase agreement with Turing Pharmaceuticals pursuant to which the Company sold Turing Pharmaceuticals its oxytocin assets, including related inventory, for a purchase price of $1.1 million, and pursuant to which Turing Pharmaceuticals also assumed certain liabilities related to the oxytocin assets.

The effect on the statement of operations and comprehensive income (loss) for 2015 was a gain of approximately $0.9 million.

MARKETABLE SECURITIES

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

MARKETABLE SECURITIES

The Company's marketable securities as of December 31, 2017 and 2016 were comprised of available-for-sale marketable securities which are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss). The amortized cost of debt securities in this category are adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income (loss). Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. All available-for-sale securities are classified as current assets, even if the maturity when acquired by the Company is greater than 1 year due to the possibility of liquidation within the next 12 months.

Marketable securities consist of the following (in thousands):



	As of December 31,
	2017		2016
Marketable Securities:
Commercial paper	6,897		30,303
Corporate debt securities	164,297		134,570
Securities of government sponsored entities	30,042		49,998
Total Marketable Securities:	$	201,236	$	214,871

The following is a summary of short-term marketable securities classified as available-for-sale as of December 31, 2017 (in thousands):



	Contractual Maturity (in years)	Amortized Cost		Unrealized Losses			Aggregate Estimated Fair Value
Marketable Securities:
Commercial paper	Less than 1	$	6,911	$	(14	)	$	6,897
Corporate debt securities	Less than 1	86,531		(198		)	86,333
Securities of government-sponsored entities	Less than 1	30,132		(90		)	30,042
Total maturity less than 1 year		123,574		(302		)	123,272
Corporate debt securities	1 to 2	78,388		(424		)	77,964
Total maturity 1 to 2 years		78,388		(424		)	77,964
Total available-for-sale securities		$	201,962	$	(726	)	$	201,236

The following is a summary of short-term marketable securities classified as available-for-sale as of December 31, 2016 (in thousands):



	Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Estimated Fair Value
Marketable Securities:
Commercial paper	Less than 1	$	30,330	$	—	$	(27	)	$	30,303
Corporate debt securities	Less than 1	64,794		7		(91		)	64,710
Securities of government-sponsored entities		19,500		—		(10		)	19,490
Total maturity less than 1 year		114,624		7		(128		)	114,503
Corporate debt securities	1 to 2	70,207		—		(347		)	69,860
Securities of government-sponsored entities	1 to 2	30,583		—		(75		)	30,508
Total maturity 1 to 2 years		100,790		—		(422		)	100,368
Total available-for-sale securities		$	215,414	$	7	$	(550	)	$	214,871

During 2017, the Company had no gains or losses on marketable securities. During 2016, the Company recognized a gain of less than $0.1 million on marketable securities. During 2015, the Company recognized a loss of $0.3 million on marketable securities. The Company had proceeds from the sale or maturity of marketable securities of $114.5 million, $159.5 million and $10.0 million for 2017, 2016 and 2015, respectively.

The primary objective of the Company’s investment portfolio is to enhance overall returns while preserving capital and liquidity. The Company’s investment policy limits interest-bearing security investments to certain types of instruments issued by institutions with primarily investment grade credit ratings and places restrictions on maturities and concentration by asset class and issuer.

The Company reviews the available-for-sale investments for other-than-temporary declines in fair value below cost basis each quarter and whenever events or changes in circumstances indicate that the cost basis of an asset may not be recoverable. This evaluation is based on a number of factors, including the length of time and the extent to which the fair value has been below the cost basis and adverse conditions related specifically to the security, including any changes to the credit rating of the security, and the intent to sell, or whether the Company will more likely than not be required to sell the security before recovery of its amortized cost basis. The assessment of whether a security is other-than-temporarily impaired could change in the future due to new developments or changes in assumptions related to any particular security. As of December 31, 2017 and 2016, the Company believed the cost basis for available-for-sale investments were recoverable in all material respects. For both December 31, 2017 and 2016, any investments in an unrealized loss position for longer than 12 months were immaterial.

DERIVATIVE FINANCIAL INSTRUMENTS

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE FINANCIAL INSTRUMENTS

Since 2013, the Company has issued 5 tranches of common stock purchase warrants to secure financing, remediate covenant violations related to the Credit Facility (See Note. 10) and provide consideration for Credit Facility amendments.

The Company accounts for derivative financial instruments in accordance with ASC 815-40, “Derivative and Hedging – Contracts in Entity’s Own Equity” (“ASC 815-40”), in which instruments which do not have fixed settlement provisions are deemed to be derivative instruments. The Company’s warrants are classified as liability instruments due to an anti-dilution provision that provides for a reduction to the exercise price of the warrants if the Company issues additional equity or equity linked instruments in the future at an effective price per share less than the exercise price then in effect.

Issuances

2015

On January 12, 2015, the Company entered into Amendment No. 3 to the Credit Facility, in which the Company obtained a commitment letter from Athyrium Capital Management, LLC and Perceptive Credit Opportunities Fund, LP (collectively, the “ Lenders”), the Company’s existing lenders, providing a commitment for a senior secured incremental term loan under the Company’s existing term loan facility in an aggregate principal amount of $30 million, which could have been drawn down at the Company’s option to finance the acquisition of the assets of Asklepion.

As consideration for the commitment letter for the Incremental Loan, the Company made a cash payment to the Lenders and issued the Lenders warrants initially exercisable to purchase up to an aggregate of 125,000 shares of the Company’s common stock. The Company recorded $1.05 million of interest expense related to the warrants upon issuance.

The Company calculated the fair value of the warrants using the Monte Carlo Simulation utilizing the following assumptions as of the grant date of the warrants:



Risk free rate	1.39		%
Expected volatility	85		%
Expected life (in years), represents the weighted average period until next liquidity event	0.3
Expected dividend yield	—
Exercise Price	$	13.25

2014

In connection with the execution of the Credit Facility, the Company issued warrants to the lenders under the Credit Facility, initially exercisable to purchase up to an aggregate of 337,500 shares of common stock of the Company. The Warrants are exercisable in whole or in part, at an initial exercise price per share of $12.76 per share, which is subject to weighted-average anti-dilution protections. The Warrants may be exercised at any time upon the election of the holder, beginning on the date of issuance and ending on the fifth anniversary of the date of issuance.

The total grant date fair value of the Warrants was $2.5 million, was recorded as a derivative liability, and is included in the debt discount to the note payable in the Consolidated Balance Sheets.

The Company calculated the fair value of the warrants using the Binomial Lattice pricing model using the following assumptions as of the grant date of the Warrants:



Risk free rate	1.62		%
Expected volatility	85		%
Expected life (in years), represents the weighted average period until next liquidity event	0.36
Expected dividend yield	—
Exercise Price	$	12.76

On November 13, 2014, the Company entered into Amendment No. 2 to the Credit Facility which allowed the Company to be in compliance with certain covenants as of September 30, 2014. In addition certain covenants related to the 4^th quarter of fiscal 2014 and 2015 were amended. As compensation for Amendment No. 2, the Company agreed to issue additional warrants to the lenders, initially exercisable to purchase an aggregate of 300,000 shares of common stock of the Company which were valued at $2.2 million as of November 13, 2014, with an exercise price of $9.96 per share, and was recorded in change in fair value of derivative instruments in the 2014 Consolidated Statements of Operations and Comprehensive Income (Loss).

Re-measurement

The warrants are re-measured at each balance sheet date based on estimated fair value. Changes in estimated fair value are recorded as non-cash valuation adjustments within other income (expenses) in the Company’s accompanying Consolidated Statements of Operations and Comprehensive Income (Loss). The Company recorded a change in the estimated fair value of warrants of a loss of $4.5 million, gain of $1.7 million, and loss of $33.3 million during the years ended December 31, 2017, 2016 and 2015, respectively.

The Company calculated the fair value of the warrants using the Black-Scholes model as of December 31, 2017 and Monte Carlo Simulation as of December 31, 2016, using the following assumptions:



	As of
	December 31, 2017		December 31, 2016
Fair value of common stock	$	21.07	$	18.93
Remaining Life (in years) of the Warrants	.1 – 2.0 years		1.2 – 3.0 years
Risk-free interest rate	1.39 - 1.89%		.89 - 1.48%
Expected volatility	33 - 43%		55 - 75%
Dividend yield	—		—

Expected volatility is based on an analysis of the Company’s volatility. The risk free interest rate is based on the U.S. Treasury security rates for the remaining term of the warrants at December 31, 2017.

The following tables presents the Company’s derivative warrant issuances and balances outstanding during the years ended December 31, 2017 and 2016:



		Weighted Average
	Warrants	Exercise Price		Grant Date Fair Value
Outstanding at December 31, 2014	3,421,355	$	6.43	$	3.79
Issued	125,000	$	13.25	$	8.40
Canceled	—	$	—	$	—
Exercised	880,807	$	5.35	$	3.23
Outstanding at December 31, 2015	2,665,548	$	7.05	$	4.20
Issued	—	—		—
Canceled	—	—		—
Exercised	898,643	6.68		4.85
Outstanding at December 31, 2016	1,766,905	$	7.23	$	3.87
Issued	—	—		—
Canceled	—	—		—
Exercised	607,481	6.00		3.33
Outstanding at December 31, 2017	1,159,424	$	7.86	$	4.15

The following information applies to derivative warrants outstanding at December 31, 2017:



Exercise Price		Number of Warrants	Weighted Average Remaining Contractual Life (years)	Number Exercisable
$	3.60	168,336	0.10	168,336
$	6.00	611,921	0.60	611,921
$	12.76	337,500	1.50	337,500
$	13.25	41,667	2.00	41,667

The total intrinsic value of derivative warrants outstanding and exercisable as of December 31, 2017 was $15.3 million. The Company’s closing stock price was $21.07 on December 31, 2017.

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

Financial Instruments and Fair Value

The Company accounts for financial instruments in accordance with ASC 820, “Fair Value Measurements and Disclosures” (“ASC 820”). ASC 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under ASC 820 are described below:

Level 1 – Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

Level 2 – Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly; and

Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

In estimating the fair value of the Company’s derivative liabilities, the Company used the Black Scholes method as of December 31, 2017 and the Monte Carlo Simulation as of December 31, 2016. Based on the fair value hierarchy, the Company classified the derivative liability within Level 3.

In estimating the fair value of the Company’s contingent consideration, the Company used the probability-based expected method as of December 31, 2017 and the comparable uncontrolled transaction (“CUT”) method in 2016 for royalty payments based on projected revenues. Based on the fair value hierarchy, the Company classified contingent consideration within Level 3 because valuation inputs are based on projected revenues discounted to a present value.

Financial instruments with carrying values approximating fair value include cash and cash equivalents, accounts receivable, notes receivable, deposits on lease agreements, and accounts payable, due to their short term nature.

The following table presents the Company’s asset and liabilities that are measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of December 31, 2017 (in thousands):



	As of December, 2017		Fair Value Hierarchy at December 31, 2017
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Asset:
Cash and Cash Equivalents	$	99,394	$	92,726	$	6,668	$	—
Marketable securities, available-for-sale	201,236		—		201,236		—
Total	$	300,630	$	92,726	$	207,904	$	—
Liabilities:
Derivative liability related to warrants	$	15,710	$	—	$	—	$	15,710
Business combination-related contingent consideration	90,000		—		—		90,000
Total	$	105,710	$	—	$	—	$	105,710

The following table presents the Company’s assets and liabilities that are measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of December 31, 2016 (in thousands):



	As of December, 2016		Fair Value Hierarchy at December 31, 2016
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Asset:
Cash and Cash Equivalents	$	41,002	$	39,929	$	1,073	$	—
Marketable securities, available-for-sale	214,871		—		214,871		—
Total	$	255,873	$	39,929	$	215,944	$	—
Liabilities:
Derivative liability related to warrants	$	22,440	$	—	$	—	$	22,440
Business combination-related contingent consideration	87,478		—		—		87,478
Total	$	109,918	$	—	$	—	$	109,918

The following table sets forth a summary of changes in the estimated fair value of the Company’s Level 3 derivative liability for years ended December 31, 2017 and 2016 (in thousands):



	Fair Value Measurements of Common Stock Warrants Using Significant Unobservable Inputs (Level 3)
	2017			2016
Balance at January 1,	$	22,440		$	38,810
Reclassification of derivative liability to equity upon exercise of warrants	(11,221		)	(14,715		)
Change in estimated fair value of liability classified warrants	4,491			(1,655		)
Balance at December 31,	$	15,710		$	22,440

The following table sets forth a summary of changes in the estimated fair value of the Company's Level 3 business combination-related contingent consideration for the years ended December 31, 2017 and 2016 (in thousands):



	Fair Value Measurements of Acquisition-Related Contingent Consideration (Level 3)
	2017			2016
Balance at January 1,	$	87,478		$	59,021
Present value of contingent consideration upon acquisition related to a business combination	—			25,000
Increase from revaluation of contingent consideration	19,389			18,383
Contractual Payments	(6,006		)	(12,826		)
Contractual Payments accrued at December 31	(11,012		)	(1,988		)
Foreign currency impact	151			(112		)
Balance at December 31,	$	90,000		$	87,478

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS

Amortizable intangible assets

Ligand License Agreement

In 2013, the Company entered into a $2.5 million agreement with Ligand for a worldwide sublicense to develop, manufacture and commercialize a drug technology compound including sparsentan (the “Ligand License Agreement”). The cost of the Ligand License Agreement, which is presented net of amortization in the accompanying Consolidated Balance Sheet in intangible assets, net, is being amortized to research and development on a straight-line basis through September 30, 2023. As consideration for the license, we are required to make substantial payments upon the achievement of certain milestones, totaling up to $109.4 million. Through 2017, we have made milestone payments to Ligand of $2.6 million under the terms of the Ligand License Agreement. Should we commercialize sparsentan or any products containing related compounds, we will be obligated to pay to Ligand an escalating annual royalty between 15% and 17% of net sales of all such products.

In September 2015, the Ligand License Agreement was amended to facilitate sub-licensing in Asia-Pacific. As consideration for the amendment the Company paid $1.0 million.

Carbetocin Technology

In September 2015, the Company wrote-off the entire value of intangible assets related to Carbetocin. The write-off was deemed appropriate as the Company elected not to pursue any internal development of the asset and attempts to divest it were unsuccessful. The total charge of $4.7 million was included in operating expenses on the Consolidated Statement of Operations and Comprehensive Income (Loss).

Manchester Pharmaceuticals LLC

The Company acquired intangible assets with finite lives related to the Chenodal product rights, trade names, and customer relationships with the values of $67.8 million, $0.2 million, and $0.4 million, respectively. The useful lives related to the acquired product rights, trade names, and customer relationships are expected to be approximately 16, 1 and, 10 years, respectively. Amortization of product rights, trade names and customer relationships are being recorded in selling, general and administrative expense over their respective lives.

In 2015, the Company divested the assets related to Vecamyl, valued at $3.6 million, to Turing Pharmaceuticals.

Thiola License Agreement

In 2014, the Company entered into a license agreement with Mission Pharmacal, in which the Company obtained an exclusive, royalty-bearing license to market, sell and commercialize Thiola (Tiopronin) in the United States and Canada, and a non-exclusive license to use know-how relating to Thiola to the extent necessary to market Thiola. The initial term of the license is 10 years and will automatically renew thereafter for periods of one year.

The Company paid Mission an up-front license fee of $3 million and will pay guaranteed minimum royalties during each calendar year the greater of $2 million or twenty percent (20%) of the Company’s net sales of Thiola through June 30, 2024. The present value of guaranteed minimum royalties payable using a discount rate of approximately 11% based on the Company’s then borrowing rate is $15.1 million and $10.1 million as of December 31, 2017 and 2016, respectively. As of December 31, 2017, the guaranteed minimum royalty current and long term liability was approximately $2.0 million and $13.1 million, respectively, and is recorded as guaranteed minimum royalty in the Consolidated Balance Sheet. As of December 31, 2016, the guaranteed minimum royalty current and long term liability was approximately $2.0 million and $8.1 million, respectively, and is recorded as guaranteed minimum royalty in the Consolidated Balance Sheet. The Company has capitalized $54.5 million related to the Thiola intangible asset which consists of the up-front license fee, professional fees, present value of the guaranteed minimum royalties and any additional payments through 2017 in excess of minimum royalties.

On November 3, 2017, the Company amended its agreement with the manufacturer of Thiola to extend the term of the current exclusive U.S. and Canada licensing agreement by an additional five years, to 2029. The royalty rate and guaranteed minimum payment were also extended through the new agreement term. Upon execution of the amendment, the Company capitalized an additional $5.9 million in intangible assets and recorded a guaranteed minimum liability for the same amount.

There are 11.5 years remaining in the term of the license agreement.

Cholbam (Kolbam) Asset Purchase

On March 31, 2015, the Company completed its acquisition from Asklepion of all worldwide rights, titles and ownership of Cholbam, including all related contracts, data assets, intellectual property, regulatory assets and the PRV. The Company capitalized $75.9 million and $7.3 million for the U.S. and international economic interest, respectively.

L-UDCA

On June 20, 2016, the Company signed a definitive agreement to purchase the rights, titles, and ownership of L-UDCA from Asklepion. The purchase included $25.5 million for an intangible asset with a definite life related to product rights for the U.S. The useful life related to the acquired product rights is expected to be approximately 17 years once the NDA is approved by the FDA. Until approval, the asset is considered IPR&D with an indefinite life and is not amortized.

Amortizable intangible assets as of December 31, 2017 (in thousands):



	Useful Life	Gross Carrying Amount		Accumulated Amortization			Net Book Value
Chenodal Product Rights	16	$	67,849	$	(15,976	)	$	51,873
Thiola License	15	54,471		(10,168		)	44,303
Economic Interest - U.S. revenue Cholbam	10	75,900		(20,903		)	54,997
Economic Interest - International revenue Cholbam	10	8,058		(2,219		)	5,839
Economic Interest - L-UDCA (acquired IPR&D)	Indefinite	25,500		—			25,500
Ligand License	11	3,300		(1,420		)	1,880
Manchester Customer Relationships	10	403		(152		)	251
Manchester Trade Name	1	175		(175		)	—
Internal use software	5	$	207	$	(33	)	$	174
Total		$	235,863	$	(51,046	)	$	184,817

Amortizable intangible assets as of December 31, 2016 (in thousands):



	Useful Life	Gross Carrying Amount		Accumulated Amortization			Net Book Value
Chenodal Product Rights	16	$	67,849	$	(11,738	)	$	56,111
Thiola License	10	35,339		(5,818		)	29,521
Economic Interest - U.S. revenue Cholbam	10	75,900		(13,320		)	62,580
Economic Interest - International revenue Cholbam	10	7,074		(1,241		)	5,833
Economic Interest - L-UDCA (acquired IPR&D)	Indefinite	25,500		—			25,500
Ligand License	11	3,300		(1,093		)	2,207
Manchester Customer Relationships	10	403		(112		)	291
Manchester Trade Name	1	175		(175		)	—
Total		$	215,540	$	(33,497	)	$	182,043

The following table summarizes amortization expense for the twelve months ended December 31, 2017, 2016 and 2015 (in thousands):



	2017		2016		2015
Research and development	$	327	$	328	$	697
Selling, general and administrative	17,004		15,665		12,534
Total amortization expense	$	17,331	$	15,993	$	13,231

As of December 31, 2017, amortization expense (excluding infinite lived IPR&D) for the next five years is expected to be as follows (in thousands):



2018	$	16,871
2019	16,871
2020	16,871
2021	16,871
2022	16,871
Thereafter	74,962
Total	$	159,317

ACCRUED EXPENSES

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

ACCRUED EXPENSES

Accrued expenses consist of the following at December 31, 2017 and 2016 (in thousands):



	2017		2016
Compensation related costs	$	7,749	$	7,441
Research and development	6,989		7,311
Government rebate reserves	5,883		6,967
Selling, general and administrative	3,896		3,333
Royalty/contingent consideration	6,429		5,766
Restructuring expenses	3,549		893
Miscellaneous accrued expenses	1,523		1,597
Total accrued expenses	$	36,018	$	33,308

NOTES PAYABLE

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

NOTES PAYABLE

Convertible Notes Payable

On May 29, 2014, the Company entered into a Note Purchase Agreement relating to a private placement by the Company of $46 million aggregate principal senior convertible notes due 2019 (the “Notes”) which are convertible into shares of the Company’s common stock at an initial conversion price of $17.41 per share. The conversion price is subject to customary anti-dilution protection. The Notes bear interest at a rate of 4.5% per annum, payable semiannually in arrears on May 15 and November 15 of each year, beginning on November 15, 2014. The Notes mature on May 30, 2019 unless earlier converted or repurchased in accordance with the terms. The aggregate carrying value of the Notes on their issuance was $43 million, which was net of the $3 million debt discount.

On June 30, 2014, the Company issued 401,047 shares of common stock to the holders of the Notes and such noteholders granted the Company a release of certain claims they may have had in connection with the Company's sale of the Notes or certain statements made by the Company in connection with such sale. The Company recorded finance expense as other expense in the amount of $4.7 million for the year ended December 31, 2014 based on the fair market value of the stock on the date of issuance in relation to the shares issued.

As of December 31, 2017 the fair value of a share of common stock was $21.07, exceeding the initial conversion price per share of the Notes. If the debt holders were to convert the Company would be required to issue 2,642,160 shares of common stock assuming that no fundamental change in the Company had occurred. The Company has reserved sufficient shares of its common stock to satisfy the conversion requirements related to the Notes. As of December 31, 2017, the convert value exceeded the carrying value by approximately $10.5 million.

In estimating the fair value of the Company’s convertible debt, the Company performed an analysis on the straight-debt portion, excluding the conversion feature and the conversion feature. To estimate the fair value of conversion feature, the Company used the Monte Carlo Simulation as of December 31, 2017. To estimate the fair value of straight-debt portion, excluding the conversion feature, the Company discounted to present value the scheduled coupon payments and principal repayment, using an appropriate fair market yield. As of December 31, 2017 the fair value of the debt was estimated at $63.6 million using level 2 inputs.

The net carrying amount of the Notes consists of the following (in thousands):



	December 31,
	2017			2016
Aggregate principle amount of Notes	$	46,000		$	46,000
Unamortized debt discount and debt issuance costs	(923		)	(1,578		)
	$	45,077		$	44,422

Credit Facility

In June 2014, the Company entered into a $45 million Credit Agreement (“Credit Facility”) which bore interest at an annual rate of (i) the Adjusted LIBOR Rate (as such term was defined in the Credit Facility) plus 10.00% or (ii) in certain circumstances, the Base Rate (as such term was defined in the Credit Agreement) plus 9.00% and was payable quarterly. The Credit Facility contained certain financial and non-financial covenants.

In connection with the execution of the Credit Facility, the Company issued warrants (the “Warrants”) to the lenders under the Credit Facility, initially exercisable to purchase up to an aggregate of 337,500 shares of common stock of the Company. The Warrants are exercisable in whole or in part, at an initial exercise price per share of $12.76 per share, which is subject to weighted-average anti-dilution protections. The Warrants could be exercised at any time upon the election of the holder, beginning on the date of issuance and ending on the fifth anniversary of the date of issuance. The issuance of the Warrants was not registered under the Securities Act of 1933, as amended (the “Securities Act”), as such issuance was exempt from registration under Section 4(2) of the Securities Act.

The total grant date fair value of the Warrants was $2.5 million, was recorded as a derivative liability, and was included in the debt discount to the note payable in the 2014 Consolidated Balance Sheets.

The Company calculated the fair value of the warrants using the Binomial Lattice pricing model using the following assumptions as of the grant date of the Warrants:



Risk free rate	1.62		%
Expected volatility	85		%
Expected life (in years), represents the weighted average period until next liquidity event	0.36
Expected dividend yield	—
Exercise Price	$	12.76

In November 2014, the Company entered into Amendment No. 2 (“Amendment No. 2”) to the Credit Facility which allowed the Company to be in compliance with certain covenants as of September 30, 2014. In addition certain covenants related to the fourth quarter of fiscal 2014 and 2015 were amended. As compensation for Amendment No. 2, the Company agreed to issue additional warrants to Athyrium Capital Management, LLC and Perceptive Credit Opportunities Fund, LP (collectively, the “Lenders”), initially exercisable to purchase an aggregate of 300,000 shares of common stock of the Company which were valued at $2.2 million and recorded in change in fair value of derivative instruments in the 2014 Consolidated Statements of Operations and Comprehensive Income (Loss).

On January 12, 2015, the Company entered into Amendment No. 3 (“Amendment No. 3”) to the Credit Facility in which the Company obtained a commitment letter from the Lenders, providing a commitment for a senior secured incremental term loan under the Company’s existing term loan facility in an aggregate principal amount of $30.0 million, which could have been drawn down at the Company’s option to finance the acquisition of the Cholbam assets from Asklepion.

As consideration for Amendment No. 3, the Company made a $0.6 million cash payment to the Lenders, recorded in finance expense in the Consolidated Statements of Operations and Comprehensive Income (Loss), and issued the Lenders warrants initially exercisable to purchase up to an aggregate of 125,000 shares of the Company’s common stock which were valued at $1.1 million on January 12, 2015 and were recorded in interest expense in the Consolidated Statements of Operations and Comprehensive Income (Loss). Due to the closing of its public offering on March 24, 2015, the Company received cash proceeds of $140.0 million, after deducting underwriting fees and other offering costs, which the Company used to make the $27.0 million payment due to Asklepion upon the closing of the Company’s acquisition of the Cholbam assets, and as a result, the Company did not utilize the commitment from the Lenders.

On July 1, 2015, the Company paid off the Credit Facility in its entirety including a prepayment premium of $2.3 million, and incurred an additional charge of $4.2 million, included in other expenses on the Company's Consolidated Statement of Operations and Comprehensive Income (Loss), for the write-off of the debt discount and equity issuances for the Credit Facility

Interest Expense

Total interest expense, net, recognized for the years ended December 31, 2017, 2016 and 2015 was $1.2 million, $0.8 million and $7.7 million, respectively.

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Leases and Sublease Agreements



Facilities	Base Rent	Lease Expiration	Comments
Occupied Location
Corporate Headquarters San Diego CA	$2.1 million	July 2024
Vacated Location
New York NY	$0.5 million	November 2018	Sublet through expiration

Contractual Commitments

The following table summarizes our principal contractual commitments, excluding open orders that support normal operations, as of December 31, 2017 (in thousands):



	Total		Less than 1 year		1-3 years		3-5 years		More than 5 years
Operating leases	$	16,037	$	2,012	$	4,757	$	5,046	$	4,222
Note payable, including contractual interest	71,933		4,070		50,863		4,000		13,000
Sales support services	2,638		417		833		833		555
Product supply contracts	1,539		1,358		181		—		—
Purchase order commitments	8,119		5,619		1,000		1,000		500
	$	100,266	$	13,476	$	57,634	$	10,879	$	18,277

Legal Proceedings

In August 2017, Martin Shkreli, the Company’s former Chief Executive Officer, was convicted on securities fraud charges following investigations by the U.S. Attorney for the Eastern District of New York and the U.S Securities and Exchange Commission. The Company was not a target of these investigations and cooperated with them fully. In connection with these proceedings, Mr. Shkreli sought advancement of his legal fees from the Company. The Company disputed its obligation to pay these amounts in full, and in November 2016, the Company and Mr. Shkreli entered into a binding settlement arrangement under which the Company advanced $2.8 million in legal fees to Mr. Shkreli’s counsel. The Company also advanced an additional $2 million in legal fees once the matter proceeded to trial. In December 2017, after Mr. Shkreli requested that the Company advance him legal fees in connection with his appeal of his conviction, the Company and Mr. Shkreli amended the November 2016 settlement arrangement, pursuant to which the Company agreed to advance Mr. Shkreli $625,000 in full satisfaction of its obligation to advance fees to Mr. Shkreli in connection with the appeal. The Company has been reimbursed by its directors’ and officers’ insurance carriers for $3.3 million of the legal fees the Company advanced in connection with the pre-trial and trial proceedings. Pending the outcome of Mr. Shkreli's appeal, the insurance carriers have reserved their rights to assert that certain of the advanced funds pertain to claims excluded from coverage under the relevant insurance policy and are therefore recoverable by the carriers. As a result, the final amount of the reimbursement from the insurance carriers is not currently estimable. In addition, a portion of the legal fees the Company has advanced to Mr. Shkreli will be subject to reimbursement by Mr. Shkreli under Delaware law in the event it is ultimately determined that Mr. Shkreli is not entitled to be indemnified by the Company in these proceedings.

In August 2015, the Company filed a lawsuit in federal district court for the Southern District of New York against Mr. Shkreli, asserting that he breached his fiduciary duty of loyalty during his tenure as the Company’s Chief Executive Officer and a member of its Board of Directors. Mr. Shkreli served a demand for JAMS arbitration on Retrophin, claiming that Retrophin had breached his December 2013 employment agreement. In response to Mr. Shkreli’s arbitration demand, the Company asserted counterclaims in the arbitration that are substantially similar to the claims it previously asserted in the federal lawsuit against Mr. Shkreli. The federal Court granted a stay of the federal lawsuit pending a determination by the arbitration panel whether the Company’s counterclaims would be litigated in the arbitration, as the Company is seeking. In April 2016, the arbitration panel granted the parties’ request for a stay of the proceedings pending settlement discussions. In connection with these proceedings, Mr. Shkreli sought advancement of his legal fees from the Company relating to his defense of the Company’s claims against him. Pursuant to the November 2016 binding term sheet, the significant majority of the existing legal fees related to these proceedings that Mr. Shkreli claimed should be advanced were offset and satisfied by a $2.025 million judgment against Mr. Shkreli in a different case, and the Company paid$0.4 million in legal fees to Mr. Shkreli's counsel. The legal fees the Company has advanced will be subject to reimbursement by Mr. Shkreli under Delaware law in the event it is ultimately determined that Mr. Shkreli is not entitled to be indemnified by the Company in these proceedings. The Company will also be subject to additional obligations when the litigation resumes, as well as advancement obligations in the interim.

For the years ended December 31, 2017 and 2016, the Company recorded $2.6 million and $5.2 million in expenses and paid $3.6 million and $1.0 million under the settlement, respectively. The Company received $2.6 million and $0.7 million in reimbursement from its directors’ and officers’ insurance carriers during the year ended December 31, 2017 and 2016, respectively. The reimbursement in 2017 is recorded as a liability on the Consolidated Balance Sheet pending the outcome of an appeal, if any.

From time to time the Company is involved in legal proceedings arising in the ordinary course of business. The Company believes there is no litigation pending that could have, individually or in the aggregate, a material adverse effect on its results of operations or financial condition.

STOCKHOLDERS’ EQUITY / DEFICIT

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

STOCKHOLDERS’ EQUITY / DEFICIT

Common Stock

The Company is currently authorized to issue up to 100,000,000 shares of $0.0001 par value common stock. All issued shares of common stock are entitled to vote on a 1 share/1 vote basis.

Preferred Stock

The Company is currently authorized to issue up to 20,000,000 shares of $0.001 par value preferred stock, of which 1,000 shares are designated Class "A" Preferred shares, $0.001 par value. Class A Preferred Shares are not entitled to interest, have certain liquidation preferences, special voting rights and other provisions. No preferred stock has been issued to date.

Public Offering - 2015

On March 24, 2015, the Company completed a public offering of 7,866,000 shares of common stock at a price of $19.00 per share. The Company received net proceeds from the offering of $140.0 million after deducting underwriting fees and other offering costs of $9.5 million. The shares of common stock were offered by the Company pursuant to a shelf registration statement that was declared effective by the SEC on March 13, 2015.

2015 Equity Incentive Plan

On June 8, 2015, the Company's stockholders approved the 2015 Equity Incentive Plan (the "2015 Plan"). The 2015 Plan is intended as the successor to and continuation of the Plan. Stockholders approved 1.4 million new shares to be issued under the 2015 Plan, in addition to 0.6 million unallocated shares remaining available for issuance under the Plan that were added to the 2015 Plan.

On May 18, 2016, the Company's stockholders approved an amendment to the 2015 Equity Incentive Plan (the "Amended 2015 Plan"). The amendment provides for an additional 1.6 million new shares to be issued under the Amended 2015 Plan, in addition to 0.7 million unallocated shares remaining available for issuance. The amendment also includes a provision where on or after March 21, 2016, the number of shares available for issuance under the Amended 2015 Plan will be reduced by one share for each share subject to a stock option or stock appreciation right and by 2.0 shares for each share subject to any other type of stock award issued pursuant to the Amended 2015 Plan, and any such shares will return to the share reserve at the same rates upon cancellation or other forfeiture of such awards or shares.

On May 17, 2017, the Company's stockholders approved an amendment to the Amended 2015 Plan. The amendment provides for an additional 1.8 million new shares to be issued under the Amended 2015 Plan.

2017 Employee Stock Purchase Plan

There are 380,000 shares of common stock available for issuance under the 2017 Employee Stock Purchase Plan ("2017 ESPP"). Beginning on January 1, 2018, and ending on (and including) January 1, 2026, the number of shares of common stock available for issuance under the 2017 ESPP shall increase by an amount equal to the lesser of (i) one percent (1%) of the total number of shares of common stock outstanding on December 31st of the preceding calendar year and (ii) 300,000 shares of common stock.

Substantially all employees are eligible to participate and, through payroll deductions, can purchase shares on established dates semi-annually. The purchase price per share sold pursuant to the 2017 ESPP will be the lower of (i) 85% of the fair market value of common stock on the first day of the offering period or (ii) 85% of the fair market value on the purchase date. Each offering period will span up to six months. Purchases may be up to 15% of qualified compensation, with an annual limit of $25,000. The 2017 ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code.

As of December 31, 2017, there were approximately 0.4 million shares authorized and 0.3 million shares reserved for future issuance under the 2017 ESPP.

Stock Options

The fair values of stock option grants during the year ended December 31, 2017, 2016 and 2015 were calculated on the date of grant using the Black-Scholes option pricing model, except for options granted for market and revenue performance criteria. Compensation expense is recognized over the period of service, generally the vesting period. During the year ended December 31, 2017, 2,111,300 stock options were granted by the Company. The following weighted average assumptions were used in the Black-Scholes options pricing model to estimate the fair value of stock options for the specified reporting periods:



	Twelve Months Ended December 31,
	2017		2016		2015
Risk free rate	2.10	%	1.20	%	1.53	%
Expected volatility	70	%	68	%	83	%
Expected life (in years)	6.1		5.8		5.8
Expected dividend yield	—		—		—

The risk-free interest rate was based on rates established by the Federal Reserve. The Company’s expected volatility was based on analysis of the Company’s volatility, as well as the volatilities of guideline companies. The expected life of the Company’s options was determined using the simplified method as a result of limited historical data regarding the Company’s activity. The dividend yield is based upon the fact that the Company has not historically paid dividends, and does not expect to pay dividends in the foreseeable future.

The following table summarizes our stock option activity and related information for the year ended December 31, 2017:



			Weighted Average
	Shares Underlying Options		Exercise Price		Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Exercisable at December 31, 2016	3,793,017		$	14.94	6.82	$	23,358
Outstanding at December 31, 2016	6,430,570		16.91		7.64	$	30,088
Granted	2,111,300		18.48		—	—
Forfeited and expired	(759,127	)	22.28		—	—
Exercised	(629,075	)	12.86		—	5,420
Outstanding at December 31, 2017	7,153,668		$	17.16	6.95	$	39,010
Exercisable at December 31, 2017	4,610,233		$	15.97	5.85	$	31,991

The following table summarizes our stock option activity and related information for the year ended December 31, 2016:



			Weighted Average
	Shares Underlying Options		Exercise Price		Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Exercisable at December 31, 2015	2,036,906		$	12.55	8.34	$	15,582
Outstanding at December 31, 2015	5,665,584		$	17.05	8.75	$	31,542
Granted	1,687,250		16.73		—	—
Forfeited and expired	(541,416	)	22.19		—	—
Exercised	(380,848	)	10.55		—	2,873
Outstanding at December 31, 2016	6,430,570		$	16.91	7.64	$	30,088
Exercisable at December 31, 2016	3,793,017		$	14.94	6.82	$	23,358

The following table summarizes our stock option activity and related information for the year ended December 31, 2015:



			Weighted Average
	Shares Underlying Options		Exercise Price		Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Exercisable at December 31, 2014	1,225,833		$	9.73	7.96	$	3,395
Outstanding at December 31, 2014	4,892,208		$	10.93	8.57	$	8,353
Granted	2,285,000		27.15		—	—
Forfeited and expired	(970,170	)	14.91		—	—
Exercised	(541,454	)	13.10		—	7,230
Outstanding at December 31, 2015	5,665,584		$	17.05	8.75	$	31,542
Exercisable at December 31, 2015	2,036,906		$	12.55	8.34	$	15,582

The weighted average grant date fair value of options granted was $11.77, $10.09, and $19.02 during the years ended December 31, 2017, 2016 and 2015, respectively. The aggregate intrinsic value for outstanding options is calculated as the difference between the exercise price of the underlying awards and the closing price of the Company’s common stock as of December 31, 2017 of $21.07. Unrecognized compensation cost associated with unvested stock options amounts to $27.9 million as of December 31, 2017, which will be expensed over a weighted average remaining vesting period of 2.6 years.

Restricted Stock Units

As of December 31, 2017, there was approximately $2.3 million of unrecognized compensation cost related to restricted stock units ("RSUs") granted. This amount is expected to be recognized over a weighted average period of 1.6 years.

The following table summarizes our restricted stock unit activity for the year ended December 31, 2017 and 2016:



	Number of RSUs		Weighted Average Grant Date Fair Value
Unvested December 31, 2015	429,666		$	20.38
Granted	245,000		17.52
Vested	(161,335	)	16.76
Forfeited/cancelled	(105,585	)	21.19
Unvested December 31, 2016	407,746		19.88
Granted	157,750		18.32
Vested	(190,498	)	17.12
Forfeited/cancelled	(29,666	)	22.00
Unvested December 31, 2017	345,332		$	20.51

Share Based Compensation

Total non-cash stock-based compensation expense consisted of the following for the years ended December 31, 2017, 2016 and 2015 (in thousands):



	Twelve Months Ended December 31,
	2017		2016		2015
Selling, general and administrative expenses	$	17,924	$	18,614	$	16,483
Research and development expenses	8,950		10,488		9,417
Total	$	26,874	$	29,102	$	25,900

Exercise of Warrants

During the twelve months ended December 31, 2017, the Company issued 607,481 shares of common stock upon the exercise of warrants for cash received by the Company in the amount of $3.6 million. The Company reclassified $11.2 million derivative liability as equity for the value of these warrants on the date of exercise. The warrants were revalued immediately prior to exercise and the change in the fair value of $3.0 million was recorded as other expense in the Consolidated Financial Statements of the Company.

During the twelve months ended December 31, 2016, the Company issued 898,633 shares of common stock upon the exercise of warrants for cash received by the Company in the amount of $6.0 million. The Company reclassified $14.7 million derivative liability as equity for the value of these warrants on the date of exercise. The warrants were revalued immediately prior to exercise and the change in the fair value of $2.9 million was recorded as other expense in the Consolidated Financial Statements of the Company.

During the twelve months ended December 31, 2015, the Company issued 870,306 shares of common stock upon the exercise of warrants for cash received by the Company in the amount of $4.5 million. The Company reclassified $23.5 million derivative liability as equity for the value of these warrants on the date of exercise. The warrants were revalued immediately prior to exercise and the change in the fair value of $2.8 million was recorded as other expense in the Consolidated Financial Statements of the Company.

Treasury Stock

In March 2015 the Company retired 379,591 shares of its common stock held as treasury stock that were purchased in 2013 and 2014 with an aggregate purchase price of $3.2 million. This was the entire holding of treasury stock.

No shares were repurchased during the years ended December 31, 2017 and 2016.

EARNINGS (LOSS) PER SHARE

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

EARNINGS (LOSS) PER SHARE

Basic earnings (loss) per share (“EPS”) represents net income (loss) attributable to common shareholders divided by the weighted average number of common shares outstanding during the measurement period. Diluted EPS represents net income attributable to common shareholders divided by the weighted average number of common shares outstanding during the measurement period while also giving effect to all potentially dilutive common shares that were outstanding during the period using the treasury stock method.

Basic and diluted EPS is calculated as follows (net income amounts are stated in thousands):



	For the year ended December 31,
	2017							2016							2015
	Shares	Net loss			EPS			Shares	Net loss			EPS			Shares	Net Income		EPS
Basic Earnings per Share	38,769,816	$	(59,731	)	$	(1.54	)	36,997,865	$	(47,903	)	$	(1.29	)	33,560,249	$	117,237	$	3.49
Dilutive shares related to warrants	—	—						1,290,147	—						—	—
Change in fair value of derivative instruments	—	—						—	(1,655		)				—	—
Convertible Debt	—	—						—	—						2,642,160	1,881
Restricted Stock	—	—						—	—						290,966	—
Stock Options	—	—						—	—						1,088,064	—
Dilutive Earnings per Share	38,769,816	$	(59,731	)	$	(1.54	)	38,288,012	$	(49,558	)	$	(1.29	)	37,581,439	$	119,118	$	3.17

For the years ended December 31, 2017, 2016 and 2015, the following shares were excluded because they were anti-dilutive:



	For the year ended December 31,
	2017	2016	2015
Convertible Debt	2,642,160	2,642,160	—
Restricted Stock	157,319	444,942	22,069
Options	7,080,998	6,286,584	1,049,375
Warrants	1,159,424	—	2,665,548
Total Anti-Dilutive Shares	11,039,901	9,373,686	3,736,992

INCOME TAXES

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

INCOME TAXES

For financial reporting purposes, net income (loss) before income taxes includes the following components (in thousands):



	Year Ended December 31,
	2017			2016			2015
United States	$	(55,611	)	$	(52,750	)	$	107,038
Foreign	(2,752		)	(4,832		)	(1,571		)
Total	$	(58,363	)	$	(57,582	)	$	105,467

The components of the provision (benefit) for income taxes, in the Consolidated Statement of Operations are as follows (in thousands):



	2017			2016			2015
Current
Federal	$	6,991		$	13,137		$	2,094
State	802			(155		)	1,709
	7,793			12,982			3,803
Deferred
Federal	(7,965		)	(18,814		)	(8,296		)
State	1,540			(3,847		)	(7,277		)
	(6,425		)	(22,661		)	(15,573		)
Total tax provision (benefit)	$	1,368		$	(9,679	)	$	(11,770	)

The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate expressed as a percentage of income (loss) before income taxes:



	2017		2016		2015
Statutory rate - federal	(35.00	)%	(35.00	)%	35.00	%
State taxes, net of federal benefit	(3.30	)%	(3.16	)%	1.53	%
Change in FV of derivative liability (warrants)	2.82	%	1.10	%	10.89	%
Change in federal tax rate	23.29	%	—	%	—	%
Bargain purchase gain	—	%	—	%	(16.04	)%
Other permanent differences	1.04	%	2.05	%	3.68	%
Tax credits	(5.79	)%	(1.58	)%	(7.85	)%
Return to provision adjustments and other true-ups	(3.48	)%	(1.15	)%	(10.40	)%
Other	1.25	%	3.09	%	(0.79	)%
Change in valuation allowance	21.62	%	16.30	%	(27.02	)%
Income tax provision (benefit)	2.45	%	(18.35	)%	(11.00	)%

The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2017 and 2016 are as follows (in thousands):



	2017			2016
Deferred Tax Assets:
Net operating loss	$	1,099		$	1,832
Research and development and other tax credits	1,599			60
Contingent consideration	23,080			32,792
Other accrued expenses	2,603			4,621
Stock based compensation	15,695			18,520
Other	358			30
	44,434			57,855
Deferred Tax Liabilities:
Intangible assets	(16,810		)	(34,153		)
Deferred gain on installment sale	—			(14,547		)
Tax basis depreciation less than book depreciation	—			—
	(16,810		)	(48,700		)

Net deferred tax assets (liabilities) before valuation allowance	27,624			9,155
Valuation allowance	(27,624		)	(15,580		)
Total deferred tax liability	$	—		$	(6,425	)

The Company has established a full valuation allowance against its U.S. federal and state deferred tax assets due to the uncertainty surrounding the realization of such assets in future periods. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which temporary differences become deductible. Management considers the scheduled reversal of deferred liabilities and tax planning strategies in making this assessment and evaluates the recoverability of the deferred tax assets as of each reporting date. At such time as it is determined that it is more likely than not that deferred assets are realizable, the valuation allowance will be reduced accordingly and recorded as a tax benefit.

The Company has recorded a valuation allowance of $27.6 million as of December 31, 2017 to reflect the estimated amount of deferred tax assets that may not be realized. The Company increased its valuation allowance by $12.0 million for the year ended December 31, 2017 largely as a result of the Tax Cuts and Jobs Act ("Tax Act"), which impacted our ability to utilize certain deferred tax assets in the future.

At December 31, 2017, the Company had available unused U.S. federal net operating loss (“NOL”) carryforwards of $5.2 million and a minimal amount of state NOL carryforwards, all of which are fully offset by a valuation allowance. The U.S. federal NOL carryforwards will expire beginning in 2030. In addition, at December 31, 2017, the Company had federal orphan drug tax credit carryforwards of $0.02 million that begin to expire in 2037 unless utilized and California Competes tax credit carryforwards of $2.0 million that begin to expire in 2022. The Company has international subsidiaries whose operations are not material for the year ended December 31, 2017.

The Company accounts for uncertain tax benefits in accordance with the provisions of ASC 740-10 of the Accounting for Uncertainty in Income Taxes. As of December 31, 2017 the Company had no unrecognized tax benefits.

The Company does not anticipate that the amount of unrecognized tax benefits as of December 31, 2017 will change materially within the following 12 months.

A reconciliation of the Company's unrecognized tax benefits for the years 2017 and 2016 is provided in the following table (in thousands):



	2017			2016
Balance as of January 1:	$	1,500		$	3,324
Increase in current period positions	—			—
Decrease in prior period positions	(1,500		)	(1,824		)
Increase in prior period positions	—			—
Balance as of December 31:	$	—		$	1,500

The Company files income tax returns in the U.S. federal jurisdiction, various state and local, and foreign jurisdictions. The Company’s income tax returns are open to examination by federal, state and foreign tax authorities, generally for the years ended December 31, 2015 and later.

The Company’s policy is to record estimated interest and penalties related to the underpayment of income taxes or unrecognized tax benefits as a component of its income tax provision. During the years ended 2017, 2016 and 2015 , the Company did not recognize any interest or penalties in its Consolidated Statements of Operations and Comprehensive Income (Loss) and there were no accruals recorded for interest or penalties at December 31, 2017 and 2016.

U.S. Tax Reform

The Tax Act was enacted on December 22, 2017. The Tax Act reduces the US federal corporate tax rate from 35% to 21%, as well as making several other significant changes to the tax law, effective January 1, 2018. Pursuant to the Securities and Exchange Commission Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), given the amount and complexity of the changes in tax law resulting from the Tax Legislation, the Company has not finalized the accounting for the income tax effects of the Tax Legislation. This includes the provisional amounts recorded related to the re-measurement of the deferred taxes and the change to our valuation allowance. The impact of the Tax Legislation may differ from this estimate, during the one-year measurement period due to, among other things, further refinement of the Company's calculation, changes in interpretations and assumptions the Company has made, guidance that may be issued and actions the Company may take as a result of the Tax Legislation.

The Company's accounting for the following elements of the Tax Act is incomplete. However, the Company was able to make reasonable estimates of certain effects and therefore, has recorded provisional amounts as follows:

Revaluation of deferred tax assets and liabilities

We have remeasured our deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21% plus state and local tax. The Company recorded a provisional decrease related to our deferred tax assets and liabilities of $13.0 million as a result of the tax rate decrease, with a corresponding adjustment to our valuation allowance for the year ended December 31, 2017.

Valuation allowances

The Company must assess whether its valuation allowance analyses for deferred tax assets are affected by various aspects of the Tax Act (e.g., deemed repatriation of deferred foreign income, future GILTI inclusions, new categories of foreign tax credits). Since, as discussed herein, the Company has recorded provisional amounts related to certain portions of the Tax Act, any corresponding determination of the need for or change in a valuation allowance is also provisional. The Company increased its valuation allowance by $12.0 million as a result of the Tax Act and its effects on the realizability of our deferred tax assets.

RETIREMENT PLAN	12 Months Ended
RETIREMENT PLAN	Dec. 31, 2017
Retirement Benefits [Abstract]
RETIREMENT PLAN	RETIREMENT PLAN The Company has a 401(k) defined contribution savings plan for the benefit of all eligible employees. Employer matching contributions were $0.6 million and $0.5 million for the years ended December 31, 2017 and 2016, respectively. There were no employer contributions for the year ended December 31, 2015.

SEGMENT INFORMATION

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

SEGMENT INFORMATION

The Company operates in one business segment, which primarily focuses on the development and commercialization of innovative therapies for people with serious and life threatening rare diseases and medical conditions. All products are included in one segment because the majority of the Company’s products have similar economic and other characteristics, including the nature of the products, type of customers, distribution methods and regulatory environment.



	Twelve months ended December 31,
	2017		2016		2015
Net product revenues by product:
Thiola	$	82,311	$	71,199	$	54,923
Bile acid products (1)	72,626		62,392		44,969
Total net product revenues	$	154,937	$	133,591	$	99,892

(1) 2015 sales of Vecamyl (divested in 2015) are immaterial and included in Bile acid products

RESTRUCTURING

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Restructuring and Related Activities Disclosure

RESTRUCTURING

On March 7, 2017, the Company initiated a plan to consolidate its operations to its corporate headquarters in San Diego, CA. The Company incurred $3.6 million in employee related separation and transitional cash charges as a result of this consolidation.

The following table presents a reconciliation of the restructuring liability recorded within accrued expenses on the Company's Condensed Consolidated Balance Sheets (in thousands):



	Twelve Months Ended December 31, 2017
Liability, beginning of period	$	893
Restructuring expenses	3,608
Cash settlements	(897		)
Adjustments to previous estimates	(55		)
Liability, end of period	$	3,549

All accrued restructuring amounts were paid as of January 31, 2018 with the exception of accrued medical benefits of $0.3 million.

PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT

Property, plant and equipment, net consisted of the following (in thousands):



	December 31,
	2017			2016
Computers and equipment	$	436		$	311
Furniture and fixtures	945			1,573
Leasehold improvements	2,071			903
Construction-in-progress	363			—
	3,815			2,787
Less: Accumulated depreciation	(585		)	(200		)
Total property and equipment, net	$	3,230		$	2,587

The construction-in-process balance consists of costs related to the Company’s leasehold improvements at its facilities in San Diego, California.

Depreciation expense for the years ended December 31, 2017, 2016 and 2015 was $0.5 million, $0.1 million and $0.1 million, respectively.

The Company has not capitalized interest related to the property and equipment purchases.

SUBSEQUENT EVENTS	12 Months Ended
SUBSEQUENT EVENTS	Dec. 31, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSQUENT EVENTS On December 16, 2017, the Company entered into a Future Acquisition Right and Joint Development Agreement (the “Option Agreement”) with Censa Pharmaceuticals Inc. (“Censa”), which by its terms became effective on January 4, 2018 upon the satisfaction of certain conditions set forth therein. Pursuant to the Option Agreement, the Company has agreed to fund certain development activities of Censa’s CNSA-001 program, in an aggregate amount expected to be approximately$16 million through proof of concept, and has the right, but not the obligation, to acquire Censa (the “Option”) on the terms and subject to the conditions set forth in a separate Agreement and Plan of Merger (the “Merger Agreement”). In exchange for the Option, on January 8, 2018, the Company paid Censa $10 million, $9 million of which was distributed to Censa’s equity holders, and is required to pay Censa an additional $5 million upon Censa’s completion of a specified development milestone set forth in the Option Agreement, all of which will be distributed to Censa’s equity holders. If the Company exercises the Option, pursuant to the terms of the Merger Agreement the Company will acquire Censa for $65 million in upfront consideration, subject to certain adjustments, paid as a combination of 20% in cash and 80% in shares of the Company’s common stock, valued at a fixed price of $21.40 per share; provided, however, that Censa may elect on behalf of its equityholders to receive the upfront consideration in 100% cash if the average price per share of the Company’s common stock for the ten trading days ending on the date the Company provides a notice of interest to exercise the Option is less than $19.26. In addition to the upfront consideration, if the Company exercises the Option and acquires Censa, the Company would be required to make further cash payments to Censa’s equityholders of up to an aggregate of $25 million if the CNSA-001 program achieves specified development and commercial milestones.

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

The following table presents selected consolidated statements of operations data for each quarter for the fiscal years ended December 31, 2017, 2016 and 2015 (unaudited, in thousands, except for per share data):



	Fourth Quarter			Third Quarter			Second Quarter			First Quarter

For the year ended December 31, 2017:
Net product sales	$	42,177		$	40,340		$	38,800		$	33,620
Total operating expenses	57,354			50,948			52,398			48,028
Operating loss	(15,177		)	(10,608		)	(13,598		)	(14,408		)
Total other income (expense), net¹	4,139			(8,409		)	(1,556		)	1,254
Loss before provision for income taxes	(11,038		)	(19,017		)	(15,154		)	(13,154		)
Income tax benefit (provision)	(6,580		)	1,223			1,925			2,064
Net income (loss)	$	(17,618	)	$	(17,794	)	$	(13,229	)	$	(11,090	)
Net Loss per common share
Basic	$	(0.45	)	$	(0.46	)	$	(0.34	)	$	(0.29	)
Diluted	$	(0.55	)	$	(0.46	)	$	(0.34	)	$	(0.32	)
For the year ended December 31, 2016:
Net product sales	$	37,327		$	33,945		$	33,311		$	29,008
Total operating expenses	55,549			54,317			44,690			37,249
Operating loss	(18,222		)	(20,372		)	(11,379		)	(8,241		)
Total other income (expense), net¹	(5,935		)	10,274			9,416			(14,387		)
Income (loss) before provision for income taxes	(12,287		)	(30,646		)	(20,795		)	6,146
Income tax benefit (provision)	3,684			(6,467		)	7,392			5,070
Net income (loss)	$	(8,603	)	$	(37,113	)	$	(13,403	)	$	11,216
Net income (loss) per common share
Basic	$	(0.23	)	$	(1.00	)	$	(0.37	)	$	0.31
Diluted	$	(0.39	)	$	(1.00	)	$	(0.37	)	$	(0.08	)

¹The Company has experienced large changes in its stock price which directly effects the fair value of derivative instruments issued by the Company. These changes in fair value are charged to other income (expense) which correspondingly incurs larges variance from period to period. See Note 5 and 6 to the Consolidated Financial Statements for further discussion.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Principles of Consolidation

Use of Estimates

Revenue Recognition

The Company sells Kolbam internationally, and these revenues are immaterial when taken in consideration of the financial statements as a whole.

Deductions from Revenue

Research and Development Costs

Employee Stock-Based Compensation



	Initial Vesting Term
Stock Options	3 to 4 years
Restricted Stock Units	2 to 3 years

Earnings (Loss) Per Share

Cash and Cash Equivalents

Marketable Securities

Trade and Notes Receivable

Trade Receivables, Net

Notes Receivable

Inventory and Related Reserves

Segment Information

Property and Equipment, net

The major classifications of property and equipment, including their respective expected useful lives, consists of the following:



Computers and equipment	3 years
Furniture and fixtures	7 years
Leasehold improvements	Shorter of length of lease or life of the asset

Intangible Assets, Net

Goodwill

Impairment of Long-Lived Assets

Contingent Consideration and Fair Value Measurement

Contingent Consideration

Level 1 – Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

Level 2 – Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly; and

Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

Income Taxes

Reclassifications

Certain reclassifications have been made to the prior year financial statements in order to conform to the current year’s presentation.

Patents

Derivative Instruments, Warrants

Derivative Financial Instruments, Warrants

Treasury Stock

The Company records treasury stock at the cost to acquire it and includes treasury stock as a component of stockholders’ equity until it is retired.

Recently Issued Accounting Pronouncements

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Vesting Award Terms



	Initial Vesting Term
Stock Options	3 to 4 years
Restricted Stock Units	2 to 3 years

Schedule of inventory, net of reserve

Inventory, net of reserve, consisted of the following at December 31, 2017 and 2016 (in thousands):



	December 31, 2017		December 31, 2016
Raw material	$	3,435	$	1,336
Finished goods	1,916		1,490
Total inventory	$	5,351	$	2,826

Schedule of major classifications of property, equipment and software, including their respective expected useful lives

The major classifications of property and equipment, including their respective expected useful lives, consists of the following:



Computers and equipment	3 years
Furniture and fixtures	7 years
Leasehold improvements	Shorter of length of lease or life of the asset

Property, plant and equipment, net consisted of the following (in thousands):



	December 31,
	2017			2016
Computers and equipment	$	436		$	311
Furniture and fixtures	945			1,573
Leasehold improvements	2,071			903
Construction-in-progress	363			—
	3,815			2,787
Less: Accumulated depreciation	(585		)	(200		)
Total property and equipment, net	$	3,230		$	2,587

BUSINESS COMBINATION AND ASSET TRANSACTIONS (Tables)

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Schedule of purchase price allocation

The purchase price allocation of $91.3 million as of the acquisition completion date of March 31, 2015 was as follows (in thousands):



Cash paid upon consummation	$	33,430
Present value of contingent consideration and service fees	42,010
Fair Value of 661,279 shares issued to Asklepion	15,844
Total Purchase Price	$	91,284
Fair Value of Assets Acquired and Liabilities Assumed
Acquired product rights-Cholbam (Intangible Asset)	$	83,200
Pediatric Priority Review Voucher	96,250
Inventory	777
Deferred tax liability	(39,880		)
Total Allocation of Purchase Price	140,347
Bargain Purchase Gain	(49,063		)
Total Purchase Price	$	91,284

The purchase price allocation of $25.5 million as of the acquisition completion date of June 16, 2016 was as follows (in thousands):



Cash paid upon consummation	$	500
Present value of contingent consideration	25,000
Total purchase price	$	25,500
Fair Value of Assets Acquired and Liabilities Assumed
Acquired product rights: L-UDCA (intangible asset)	$	25,500
Total purchase price	$	25,500

MARKETABLE SECURITIES (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of marketable securities

Marketable securities consist of the following (in thousands):



	As of December 31,
	2017		2016
Marketable Securities:
Commercial paper	6,897		30,303
Corporate debt securities	164,297		134,570
Securities of government sponsored entities	30,042		49,998
Total Marketable Securities:	$	201,236	$	214,871

Schedule of available for sale securities

The following is a summary of short-term marketable securities classified as available-for-sale as of December 31, 2017 (in thousands):



	Contractual Maturity (in years)	Amortized Cost		Unrealized Losses			Aggregate Estimated Fair Value
Marketable Securities:
Commercial paper	Less than 1	$	6,911	$	(14	)	$	6,897
Corporate debt securities	Less than 1	86,531		(198		)	86,333
Securities of government-sponsored entities	Less than 1	30,132		(90		)	30,042
Total maturity less than 1 year		123,574		(302		)	123,272
Corporate debt securities	1 to 2	78,388		(424		)	77,964
Total maturity 1 to 2 years		78,388		(424		)	77,964
Total available-for-sale securities		$	201,962	$	(726	)	$	201,236

The following is a summary of short-term marketable securities classified as available-for-sale as of December 31, 2016 (in thousands):



	Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Estimated Fair Value
Marketable Securities:
Commercial paper	Less than 1	$	30,330	$	—	$	(27	)	$	30,303
Corporate debt securities	Less than 1	64,794		7		(91		)	64,710
Securities of government-sponsored entities		19,500		—		(10		)	19,490
Total maturity less than 1 year		114,624		7		(128		)	114,503
Corporate debt securities	1 to 2	70,207		—		(347		)	69,860
Securities of government-sponsored entities	1 to 2	30,583		—		(75		)	30,508
Total maturity 1 to 2 years		100,790		—		(422		)	100,368
Total available-for-sale securities		$	215,414	$	7	$	(550	)	$	214,871

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of assumptions for valuation of warrants

The Company calculated the fair value of the warrants using the Monte Carlo Simulation utilizing the following assumptions as of the grant date of the warrants:



Risk free rate	1.39		%
Expected volatility	85		%
Expected life (in years), represents the weighted average period until next liquidity event	0.3
Expected dividend yield	—
Exercise Price	$	13.25

The Company calculated the fair value of the warrants using the Binomial Lattice pricing model using the following assumptions as of the grant date of the Warrants:



Risk free rate	1.62		%
Expected volatility	85		%
Expected life (in years), represents the weighted average period until next liquidity event	0.36
Expected dividend yield	—
Exercise Price	$	12.76

The Company calculated the fair value of the warrants using the Black-Scholes model as of December 31, 2017 and Monte Carlo Simulation as of December 31, 2016, using the following assumptions:



	As of
	December 31, 2017		December 31, 2016
Fair value of common stock	$	21.07	$	18.93
Remaining Life (in years) of the Warrants	.1 – 2.0 years		1.2 – 3.0 years
Risk-free interest rate	1.39 - 1.89%		.89 - 1.48%
Expected volatility	33 - 43%		55 - 75%
Dividend yield	—		—

Schedule of derivative warrant issuances and balances outstanding

The following tables presents the Company’s derivative warrant issuances and balances outstanding during the years ended December 31, 2017 and 2016:



		Weighted Average
	Warrants	Exercise Price		Grant Date Fair Value
Outstanding at December 31, 2014	3,421,355	$	6.43	$	3.79
Issued	125,000	$	13.25	$	8.40
Canceled	—	$	—	$	—
Exercised	880,807	$	5.35	$	3.23
Outstanding at December 31, 2015	2,665,548	$	7.05	$	4.20
Issued	—	—		—
Canceled	—	—		—
Exercised	898,643	6.68		4.85
Outstanding at December 31, 2016	1,766,905	$	7.23	$	3.87
Issued	—	—		—
Canceled	—	—		—
Exercised	607,481	6.00		3.33
Outstanding at December 31, 2017	1,159,424	$	7.86	$	4.15

Schedule of derivative warrants outstanding

The following information applies to derivative warrants outstanding at December 31, 2017:



Exercise Price		Number of Warrants	Weighted Average Remaining Contractual Life (years)	Number Exercisable
$	3.60	168,336	0.10	168,336
$	6.00	611,921	0.60	611,921
$	12.76	337,500	1.50	337,500
$	13.25	41,667	2.00	41,667

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of fair value on a recurring basis



	As of December, 2017		Fair Value Hierarchy at December 31, 2017
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Asset:
Cash and Cash Equivalents	$	99,394	$	92,726	$	6,668	$	—
Marketable securities, available-for-sale	201,236		—		201,236		—
Total	$	300,630	$	92,726	$	207,904	$	—
Liabilities:
Derivative liability related to warrants	$	15,710	$	—	$	—	$	15,710
Business combination-related contingent consideration	90,000		—		—		90,000
Total	$	105,710	$	—	$	—	$	105,710



	As of December, 2016		Fair Value Hierarchy at December 31, 2016
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Asset:
Cash and Cash Equivalents	$	41,002	$	39,929	$	1,073	$	—
Marketable securities, available-for-sale	214,871		—		214,871		—
Total	$	255,873	$	39,929	$	215,944	$	—
Liabilities:
Derivative liability related to warrants	$	22,440	$	—	$	—	$	22,440
Business combination-related contingent consideration	87,478		—		—		87,478
Total	$	109,918	$	—	$	—	$	109,918

Schedule of fair value measurements of common stock warrants using significant unobservable inputs (Level 3)

The following table sets forth a summary of changes in the estimated fair value of the Company’s Level 3 derivative liability for years ended December 31, 2017 and 2016 (in thousands):



	Fair Value Measurements of Common Stock Warrants Using Significant Unobservable Inputs (Level 3)
	2017			2016
Balance at January 1,	$	22,440		$	38,810
Reclassification of derivative liability to equity upon exercise of warrants	(11,221		)	(14,715		)
Change in estimated fair value of liability classified warrants	4,491			(1,655		)
Balance at December 31,	$	15,710		$	22,440

Schedule of fair value measurements of acquisition-related contingent consideration



	Fair Value Measurements of Acquisition-Related Contingent Consideration (Level 3)
	2017			2016
Balance at January 1,	$	87,478		$	59,021
Present value of contingent consideration upon acquisition related to a business combination	—			25,000
Increase from revaluation of contingent consideration	19,389			18,383
Contractual Payments	(6,006		)	(12,826		)
Contractual Payments accrued at December 31	(11,012		)	(1,988		)
Foreign currency impact	151			(112		)
Balance at December 31,	$	90,000		$	87,478

INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of amortizable intangible assets

Amortizable intangible assets as of December 31, 2017 (in thousands):



	Useful Life	Gross Carrying Amount		Accumulated Amortization			Net Book Value
Chenodal Product Rights	16	$	67,849	$	(15,976	)	$	51,873
Thiola License	15	54,471		(10,168		)	44,303
Economic Interest - U.S. revenue Cholbam	10	75,900		(20,903		)	54,997
Economic Interest - International revenue Cholbam	10	8,058		(2,219		)	5,839
Economic Interest - L-UDCA (acquired IPR&D)	Indefinite	25,500		—			25,500
Ligand License	11	3,300		(1,420		)	1,880
Manchester Customer Relationships	10	403		(152		)	251
Manchester Trade Name	1	175		(175		)	—
Internal use software	5	$	207	$	(33	)	$	174
Total		$	235,863	$	(51,046	)	$	184,817

Amortizable intangible assets as of December 31, 2016 (in thousands):



	Useful Life	Gross Carrying Amount		Accumulated Amortization			Net Book Value
Chenodal Product Rights	16	$	67,849	$	(11,738	)	$	56,111
Thiola License	10	35,339		(5,818		)	29,521
Economic Interest - U.S. revenue Cholbam	10	75,900		(13,320		)	62,580
Economic Interest - International revenue Cholbam	10	7,074		(1,241		)	5,833
Economic Interest - L-UDCA (acquired IPR&D)	Indefinite	25,500		—			25,500
Ligand License	11	3,300		(1,093		)	2,207
Manchester Customer Relationships	10	403		(112		)	291
Manchester Trade Name	1	175		(175		)	—
Total		$	215,540	$	(33,497	)	$	182,043

Schedule of amortization expense for the next 5 years

As of December 31, 2017, amortization expense (excluding infinite lived IPR&D) for the next five years is expected to be as follows (in thousands):



2018	$	16,871
2019	16,871
2020	16,871
2021	16,871
2022	16,871
Thereafter	74,962
Total	$	159,317

The following table summarizes amortization expense for the twelve months ended December 31, 2017, 2016 and 2015 (in thousands):



	2017		2016		2015
Research and development	$	327	$	328	$	697
Selling, general and administrative	17,004		15,665		12,534
Total amortization expense	$	17,331	$	15,993	$	13,231

ACCRUED EXPENSES (Tables)

12 Months Ended

Dec. 31, 2017

Payables and Accruals [Abstract]

Schedule of accrued expenses

Accrued expenses consist of the following at December 31, 2017 and 2016 (in thousands):



	2017		2016
Compensation related costs	$	7,749	$	7,441
Research and development	6,989		7,311
Government rebate reserves	5,883		6,967
Selling, general and administrative	3,896		3,333
Royalty/contingent consideration	6,429		5,766
Restructuring expenses	3,549		893
Miscellaneous accrued expenses	1,523		1,597
Total accrued expenses	$	36,018	$	33,308

NOTES PAYABLE (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of net carrying amount of debt

The net carrying amount of the Notes consists of the following (in thousands):



	December 31,
	2017			2016
Aggregate principle amount of Notes	$	46,000		$	46,000
Unamortized debt discount and debt issuance costs	(923		)	(1,578		)
	$	45,077		$	44,422

Schedule of fair value of warrants

The Company calculated the fair value of the warrants using the Binomial Lattice pricing model using the following assumptions as of the grant date of the Warrants:



Risk free rate	1.62		%
Expected volatility	85		%
Expected life (in years), represents the weighted average period until next liquidity event	0.36
Expected dividend yield	—
Exercise Price	$	12.76

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Lease and Sublease Agreements

Leases and Sublease Agreements



Facilities	Base Rent	Lease Expiration	Comments
Occupied Location
Corporate Headquarters San Diego CA	$2.1 million	July 2024
Vacated Location
New York NY	$0.5 million	November 2018	Sublet through expiration

Schedule of principal contractual commitments, excluding open orders

The following table summarizes our principal contractual commitments, excluding open orders that support normal operations, as of December 31, 2017 (in thousands):



	Total		Less than 1 year		1-3 years		3-5 years		More than 5 years
Operating leases	$	16,037	$	2,012	$	4,757	$	5,046	$	4,222
Note payable, including contractual interest	71,933		4,070		50,863		4,000		13,000
Sales support services	2,638		417		833		833		555
Product supply contracts	1,539		1,358		181		—		—
Purchase order commitments	8,119		5,619		1,000		1,000		500
	$	100,266	$	13,476	$	57,634	$	10,879	$	18,277

STOCKHOLDERS’ EQUITY / DEFICIT (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Assumptions used in Black-Scholes options pricing model

The following weighted average assumptions were used in the Black-Scholes options pricing model to estimate the fair value of stock options for the specified reporting periods:



	Twelve Months Ended December 31,
	2017		2016		2015
Risk free rate	2.10	%	1.20	%	1.53	%
Expected volatility	70	%	68	%	83	%
Expected life (in years)	6.1		5.8		5.8
Expected dividend yield	—		—		—

Schedule of stock option activity

The following table summarizes our stock option activity and related information for the year ended December 31, 2017:



			Weighted Average
	Shares Underlying Options		Exercise Price		Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Exercisable at December 31, 2016	3,793,017		$	14.94	6.82	$	23,358
Outstanding at December 31, 2016	6,430,570		16.91		7.64	$	30,088
Granted	2,111,300		18.48		—	—
Forfeited and expired	(759,127	)	22.28		—	—
Exercised	(629,075	)	12.86		—	5,420
Outstanding at December 31, 2017	7,153,668		$	17.16	6.95	$	39,010
Exercisable at December 31, 2017	4,610,233		$	15.97	5.85	$	31,991

The following table summarizes our stock option activity and related information for the year ended December 31, 2016:



			Weighted Average
	Shares Underlying Options		Exercise Price		Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Exercisable at December 31, 2015	2,036,906		$	12.55	8.34	$	15,582
Outstanding at December 31, 2015	5,665,584		$	17.05	8.75	$	31,542
Granted	1,687,250		16.73		—	—
Forfeited and expired	(541,416	)	22.19		—	—
Exercised	(380,848	)	10.55		—	2,873
Outstanding at December 31, 2016	6,430,570		$	16.91	7.64	$	30,088
Exercisable at December 31, 2016	3,793,017		$	14.94	6.82	$	23,358

The following table summarizes our stock option activity and related information for the year ended December 31, 2015:



			Weighted Average
	Shares Underlying Options		Exercise Price		Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Exercisable at December 31, 2014	1,225,833		$	9.73	7.96	$	3,395
Outstanding at December 31, 2014	4,892,208		$	10.93	8.57	$	8,353
Granted	2,285,000		27.15		—	—
Forfeited and expired	(970,170	)	14.91		—	—
Exercised	(541,454	)	13.10		—	7,230
Outstanding at December 31, 2015	5,665,584		$	17.05	8.75	$	31,542
Exercisable at December 31, 2015	2,036,906		$	12.55	8.34	$	15,582

Schedule of unvested restricted shares

The following table summarizes our restricted stock unit activity for the year ended December 31, 2017 and 2016:



	Number of RSUs		Weighted Average Grant Date Fair Value
Unvested December 31, 2015	429,666		$	20.38
Granted	245,000		17.52
Vested	(161,335	)	16.76
Forfeited/cancelled	(105,585	)	21.19
Unvested December 31, 2016	407,746		19.88
Granted	157,750		18.32
Vested	(190,498	)	17.12
Forfeited/cancelled	(29,666	)	22.00
Unvested December 31, 2017	345,332		$	20.51

Schedule of share based compensation expenses

Total non-cash stock-based compensation expense consisted of the following for the years ended December 31, 2017, 2016 and 2015 (in thousands):



	Twelve Months Ended December 31,
	2017		2016		2015
Selling, general and administrative expenses	$	17,924	$	18,614	$	16,483
Research and development expenses	8,950		10,488		9,417
Total	$	26,874	$	29,102	$	25,900

EARNINGS (LOSS) PER SHARE (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of basic and diluted net loss per share

Basic and diluted EPS is calculated as follows (net income amounts are stated in thousands):



	For the year ended December 31,
	2017							2016							2015
	Shares	Net loss			EPS			Shares	Net loss			EPS			Shares	Net Income		EPS
Basic Earnings per Share	38,769,816	$	(59,731	)	$	(1.54	)	36,997,865	$	(47,903	)	$	(1.29	)	33,560,249	$	117,237	$	3.49
Dilutive shares related to warrants	—	—						1,290,147	—						—	—
Change in fair value of derivative instruments	—	—						—	(1,655		)				—	—
Convertible Debt	—	—						—	—						2,642,160	1,881
Restricted Stock	—	—						—	—						290,966	—
Stock Options	—	—						—	—						1,088,064	—
Dilutive Earnings per Share	38,769,816	$	(59,731	)	$	(1.54	)	38,288,012	$	(49,558	)	$	(1.29	)	37,581,439	$	119,118	$	3.17

Schedule of common stock options, convertible debt and restricted stock units anti-dilutive

For the years ended December 31, 2017, 2016 and 2015, the following shares were excluded because they were anti-dilutive:



	For the year ended December 31,
	2017	2016	2015
Convertible Debt	2,642,160	2,642,160	—
Restricted Stock	157,319	444,942	22,069
Options	7,080,998	6,286,584	1,049,375
Warrants	1,159,424	—	2,665,548
Total Anti-Dilutive Shares	11,039,901	9,373,686	3,736,992

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of components of net income before incomes taxes

For financial reporting purposes, net income (loss) before income taxes includes the following components (in thousands):



	Year Ended December 31,
	2017			2016			2015
United States	$	(55,611	)	$	(52,750	)	$	107,038
Foreign	(2,752		)	(4,832		)	(1,571		)
Total	$	(58,363	)	$	(57,582	)	$	105,467

Schedule of income tax provision

The components of the provision (benefit) for income taxes, in the Consolidated Statement of Operations are as follows (in thousands):



	2017			2016			2015
Current
Federal	$	6,991		$	13,137		$	2,094
State	802			(155		)	1,709
	7,793			12,982			3,803
Deferred
Federal	(7,965		)	(18,814		)	(8,296		)
State	1,540			(3,847		)	(7,277		)
	(6,425		)	(22,661		)	(15,573		)
Total tax provision (benefit)	$	1,368		$	(9,679	)	$	(11,770	)

Schedule of reconciliation of the statutory federal income tax expense (benefit)

The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate expressed as a percentage of income (loss) before income taxes:



	2017		2016		2015
Statutory rate - federal	(35.00	)%	(35.00	)%	35.00	%
State taxes, net of federal benefit	(3.30	)%	(3.16	)%	1.53	%
Change in FV of derivative liability (warrants)	2.82	%	1.10	%	10.89	%
Change in federal tax rate	23.29	%	—	%	—	%
Bargain purchase gain	—	%	—	%	(16.04	)%
Other permanent differences	1.04	%	2.05	%	3.68	%
Tax credits	(5.79	)%	(1.58	)%	(7.85	)%
Return to provision adjustments and other true-ups	(3.48	)%	(1.15	)%	(10.40	)%
Other	1.25	%	3.09	%	(0.79	)%
Change in valuation allowance	21.62	%	16.30	%	(27.02	)%
Income tax provision (benefit)	2.45	%	(18.35	)%	(11.00	)%

Schedule of deferred tax assets and liabilities

The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2017 and 2016 are as follows (in thousands):



	2017			2016
Deferred Tax Assets:
Net operating loss	$	1,099		$	1,832
Research and development and other tax credits	1,599			60
Contingent consideration	23,080			32,792
Other accrued expenses	2,603			4,621
Stock based compensation	15,695			18,520
Other	358			30
	44,434			57,855
Deferred Tax Liabilities:
Intangible assets	(16,810		)	(34,153		)
Deferred gain on installment sale	—			(14,547		)
Tax basis depreciation less than book depreciation	—			—
	(16,810		)	(48,700		)

Net deferred tax assets (liabilities) before valuation allowance	27,624			9,155
Valuation allowance	(27,624		)	(15,580		)
Total deferred tax liability	$	—		$	(6,425	)

Schedule of unrecognized tax benefits

A reconciliation of the Company's unrecognized tax benefits for the years 2017 and 2016 is provided in the following table (in thousands):



	2017			2016
Balance as of January 1:	$	1,500		$	3,324
Increase in current period positions	—			—
Decrease in prior period positions	(1,500		)	(1,824		)
Increase in prior period positions	—			—
Balance as of December 31:	$	—		$	1,500

SEGMENT INFORMATION (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

All products are included in one segment because the majority of the Company’s products have similar economic and other characteristics, including the nature of the products, type of customers, distribution methods and regulatory environment.



	Twelve months ended December 31,
	2017		2016		2015
Net product revenues by product:
Thiola	$	82,311	$	71,199	$	54,923
Bile acid products (1)	72,626		62,392		44,969
Total net product revenues	$	154,937	$	133,591	$	99,892

RESTRUCTURING (Tables)

12 Months Ended

Dec. 31, 2017

Restructuring and Related Activities [Abstract]

Schedule of Restructuring Reserve by Type of Cost

The following table presents a reconciliation of the restructuring liability recorded within accrued expenses on the Company's Condensed Consolidated Balance Sheets (in thousands):



	Twelve Months Ended December 31, 2017
Liability, beginning of period	$	893
Restructuring expenses	3,608
Cash settlements	(897		)
Adjustments to previous estimates	(55		)
Liability, end of period	$	3,549

PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Summary of Property, Plant, and Equipment

The major classifications of property and equipment, including their respective expected useful lives, consists of the following:



Computers and equipment	3 years
Furniture and fixtures	7 years
Leasehold improvements	Shorter of length of lease or life of the asset

Property, plant and equipment, net consisted of the following (in thousands):



	December 31,
	2017			2016
Computers and equipment	$	436		$	311
Furniture and fixtures	945			1,573
Leasehold improvements	2,071			903
Construction-in-progress	363			—
	3,815			2,787
Less: Accumulated depreciation	(585		)	(200		)
Total property and equipment, net	$	3,230		$	2,587

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of Consolidated Statements of Operations data for each quarter



	Fourth Quarter			Third Quarter			Second Quarter			First Quarter

For the year ended December 31, 2017:
Net product sales	$	42,177		$	40,340		$	38,800		$	33,620
Total operating expenses	57,354			50,948			52,398			48,028
Operating loss	(15,177		)	(10,608		)	(13,598		)	(14,408		)
Total other income (expense), net¹	4,139			(8,409		)	(1,556		)	1,254
Loss before provision for income taxes	(11,038		)	(19,017		)	(15,154		)	(13,154		)
Income tax benefit (provision)	(6,580		)	1,223			1,925			2,064
Net income (loss)	$	(17,618	)	$	(17,794	)	$	(13,229	)	$	(11,090	)
Net Loss per common share
Basic	$	(0.45	)	$	(0.46	)	$	(0.34	)	$	(0.29	)
Diluted	$	(0.55	)	$	(0.46	)	$	(0.34	)	$	(0.32	)
For the year ended December 31, 2016:
Net product sales	$	37,327		$	33,945		$	33,311		$	29,008
Total operating expenses	55,549			54,317			44,690			37,249
Operating loss	(18,222		)	(20,372		)	(11,379		)	(8,241		)
Total other income (expense), net¹	(5,935		)	10,274			9,416			(14,387		)
Income (loss) before provision for income taxes	(12,287		)	(30,646		)	(20,795		)	6,146
Income tax benefit (provision)	3,684			(6,467		)	7,392			5,070
Net income (loss)	$	(8,603	)	$	(37,113	)	$	(13,403	)	$	11,216
Net income (loss) per common share
Basic	$	(0.23	)	$	(1.00	)	$	(0.37	)	$	0.31
Diluted	$	(0.39	)	$	(1.00	)	$	(0.37	)	$	(0.08	)

DESCRIPTION OF BUSINESS - Narrative (Details)	Dec. 31, 2017 product
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products sold	3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Vesting Awards (Details)	12 Months Ended
	Dec. 31, 2017
Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Stock Options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	4 years
Restricted Stock Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	2 years
Restricted Stock Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)		3 Months Ended								12 Months Ended
	Jul. 02, 2015 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment reporting_unit	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Allowance for doubtful accounts		$ 200,000				$ 300,000				$ 200,000	$ 300,000
Bad debt expense										200,000	200,000	$ 0
Inventory reserve		700,000				600,000				$ 700,000	600,000
Number of segments \| segment										1
Number of reporting units \| reporting_unit										1
Goodwill, impairment										$ 0	0	0
Impairment of intangible assets										0	0	4,700,000
Income tax provision (benefit)		7,000	$ (1,000)	$ (2,000)	$ (2,000)	(3,684,000)	$ 6,467,000	$ (7,392,000)	$ (5,070,000)	1,368,000	(9,679,000)	(11,770,000)
Reclassification payments made for contingent consideration, financing, to operating activities										(5,445,000)	3,849,000	(101,602,000)
Adoption of ASU 2016-16 required de-recognition of intra-company deferred tax assets						(4,868,000)					(4,868,000)
Investments that would be affected by ASU 2016-16		201,236,000				214,871,000				201,236,000	214,871,000
Derivative liability related to warrants		$ 15,710,000				22,440,000				15,710,000	22,440,000
Change in fair value of contingent consideration										19,389,000	18,383,000	13,778,000
Asklepion Pharmaceuticals LLC \| Asset Purchase Agreement
Summary Of Significant Accounting Policies [Line Items]
Proceeds from sale of assets	$ 245,000,000
Discount rate of receivables	2.80%
Interest Expense \| Asklepion Pharmaceuticals LLC \| Asset Purchase Agreement
Summary Of Significant Accounting Policies [Line Items]
Accretion on the notes receivable										$ 700,000	1,900,000
Accounting Standards Update 2016-15
Summary Of Significant Accounting Policies [Line Items]
Reclassification payments made for contingent consideration, financing, to operating activities											1,900,000	800,000
Accounting Standards Update 2016-16
Summary Of Significant Accounting Policies [Line Items]
Adoption of ASU 2016-16 required de-recognition of intra-company deferred tax assets						$ 4,900,000					4,900,000
Pro Forma \| Accounting Standards Update 2016-09
Summary Of Significant Accounting Policies [Line Items]
Income tax provision (benefit)											$ 400,000	$ (2,400,000)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Inventory, Net of Reserve (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Raw material	$ 3,435	$ 1,336
Finished goods	1,916	1,490
Total inventory	$ 5,351	$ 2,826

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Computers and equipment
Property, Plant and Equipment [Line Items]
Use life (in years)	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Use life (in years)	7 years

BUSINESS COMBINATION AND ASSET TRANSACTIONS - Amendment to Trademark License and Supply Agreement (Details) - Thiola License - USD ($) $ in Thousands	Nov. 03, 2017	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Licensing agreement, extension term	5 years
Finite-lived intangible asset, gross	$ 5,900	$ 54,471	$ 35,339

BUSINESS COMBINATION AND ASSET TRANSACTIONS - Acquisition of Liquid Ursodeoxycholic Acid (L-UDCA) Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 20, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 16, 2016
Business Acquisition [Line Items]
Acquisition related contingent consideration		$ 80,900	$ 71,328
Economic Interest - L-UDCA (acquired IPR&D)
Business Acquisition [Line Items]
Intangible assets acquired with definite lives	$ 25,500
Assets useful life (in years)	17 years	17 years
Present value of contingent consideration	$ 25,000			$ 25,000
Discount rate percentage	12.00%
Acquisition related contingent consideration	$ 70,300
Total Purchase Price	$ 25,500			$ 25,500

BUSINESS COMBINATION AND ASSET TRANSACTIONS - Acquisition of Liquid Ursodeoxycholic Acid (L-UDCA) Assets Acquired (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 16, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 20, 2016
Business Acquisition [Line Items]
Cash paid upon consummation		$ 0	$ 500	$ 33,430
Economic Interest - L-UDCA (acquired IPR&D)
Business Acquisition [Line Items]
Cash paid upon consummation	$ 500
Present value of contingent consideration	25,000				$ 25,000
Total purchase price	25,500				$ 25,500
Intangible assets acquired	25,500
Total purchase price	$ 25,500

BUSINESS COMBINATION AND ASSET TRANSACTIONS - Acquisition of Cholbam Narrative (Details) - USD ($) $ in Thousands			12 Months Ended
	Mar. 31, 2015	Feb. 12, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Acquisition related contingent consideration			$ 80,900	$ 71,328
Product rights
Business Acquisition [Line Items]
Assets useful life (in years)			16 years	16 years
Asklepion Pharmaceuticals LLC
Business Acquisition [Line Items]
Cash payment	$ 28,400
Common stock shares issued (in shares)	661,279
Value of common stock	$ 15,844
Acquisition related contingent consideration					$ 39,100
Fair value of Pediatric Priority Review Voucher	96,250
Discount rate percentage					19.00%
Contingent consideration agreement, high amount					$ 78,400
Net present value of service fees				$ 2,900
Total payments of service fees				$ 4,000
Deferred tax liability assumed	39,880
Assets acquired in business combination	$ 88,500
Utilized tax rate percentage	45.40%
Purchase price allocation	$ 91,284
Asklepion Pharmaceuticals LLC \| Product rights
Business Acquisition [Line Items]
Intangible assets acquired	$ 83,200
Assets useful life (in years)	10 years
Asklepion Pharmaceuticals LLC \| United States \| Product rights
Business Acquisition [Line Items]
Intangible assets acquired	$ 75,900
Asklepion Pharmaceuticals LLC \| International \| Product rights
Business Acquisition [Line Items]
Intangible assets acquired	7,300
Asklepion Pharmaceuticals LLC \| Definitive Agreement
Business Acquisition [Line Items]
Upfront payment		$ 5,000
Asklepion Pharmaceuticals LLC \| Purchase Agreement
Business Acquisition [Line Items]
Value of common stock	$ 9,000

BUSINESS COMBINATION AND ASSET TRANSACTIONS - Acquisition of Cholbam Purchase Price Allocation (Details) - USD ($) $ in Thousands		12 Months Ended
	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Cash paid upon consummation		$ 0	$ 500	$ 33,430
Asklepion Pharmaceuticals LLC
Business Acquisition [Line Items]
Cash paid upon consummation	$ 33,430
Present value of contingent consideration and service fees	42,010
Fair Value of 661,279 shares issued to Asklepion	15,844
Total Purchase Price	91,284
Fair Value of Assets Acquired and Liabilities Assumed
Pediatric Priority Review Voucher	96,250
Inventory	777
Deferred tax liability	(39,880)
Total Allocation of Purchase Price	140,347
Bargain Purchase Gain	(49,063)
Total Purchase Price	91,284
Asklepion Pharmaceuticals LLC \| Product rights
Fair Value of Assets Acquired and Liabilities Assumed
Acquired product rights-Cholbam (Intangible Asset)	$ 83,200

BUSINESS COMBINATION AND ASSET TRANSACTIONS - Divestiture of Assets (Details) - USD ($) $ in Millions				12 Months Ended
	Jul. 02, 2015	Feb. 13, 2015	Jan. 09, 2015	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impact related to divestitures				$ 0.9
Asset Purchase Agreement \| Asklepion Pharmaceuticals LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets	$ 245.0
Discount rate of receivables	2.80%
Gain on sale of intangible assets	$ 140.0
Disposal fees	4.9
Asset Purchase Agreement \| Turing Pharmaceuticals
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales value of product rights		$ 1.1	$ 1.0
At Time Of Closing \| Asset Purchase Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
PV of short term and long term receivables	46.2
At Time Of Closing \| Asset Purchase Agreement \| Asklepion Pharmaceuticals LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets	150.0
Due On First And Second Anniversaries Of Closing \| Asset Purchase Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets	47.5
PV of short term and long term receivables	44.9
Due On First And Second Anniversaries Of Closing \| Asset Purchase Agreement \| Asklepion Pharmaceuticals LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets	$ 47.5
Manchester Pharmaceuticals LLC \| Asset Purchase Agreement \| Turing Pharmaceuticals
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales value of product rights		0.3
Manchester Pharmaceuticals LLC \| Asset Purchase Agreement \| Waldun Pharmaceuticals, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales value of product rights		$ 0.7

MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	12 Months Ended
MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Marketable securities	$ 201,236	$ 214,871
Realized gain (loss) on marketable securities	100		$ (300)
Proceeds from the sale/maturity of marketable securities	114,526	159,520	$ 9,977
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Marketable securities	6,897	30,303
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities	164,297	134,570
Securities of government sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Marketable securities	$ 30,042	$ 49,998

MARKETABLE SECURITIES - Available for Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 201,962	$ 215,414
Unrealized Gains		7
Unrealized Losses	(726)	(550)
Aggregate Estimated Fair Value	201,236	214,871
Less than 1
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	123,574	114,624
Unrealized Gains		7
Unrealized Losses	(302)	(128)
Aggregate Estimated Fair Value	123,272	114,503
1 to 2 years
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	78,388	100,790
Unrealized Gains		0
Unrealized Losses	(424)	(422)
Aggregate Estimated Fair Value	77,964	100,368
Commercial paper \| Less than 1
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,911	30,330
Unrealized Gains		0
Unrealized Losses	(14)	(27)
Aggregate Estimated Fair Value	6,897	30,303
Corporate debt securities \| Less than 1
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	86,531	64,794
Unrealized Gains		7
Unrealized Losses	(198)	(91)
Aggregate Estimated Fair Value	86,333	64,710
Corporate debt securities \| 1 to 2 years
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	78,388	70,207
Unrealized Gains		0
Unrealized Losses	(424)	(347)
Aggregate Estimated Fair Value	77,964	69,860
Securities of government sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		19,500
Unrealized Gains		0
Unrealized Losses		(10)
Aggregate Estimated Fair Value		19,490
Securities of government sponsored entities \| Less than 1
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,132
Unrealized Losses	(90)
Aggregate Estimated Fair Value	$ 30,042
Securities of government sponsored entities \| 1 to 2 years
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		30,583
Unrealized Gains		0
Unrealized Losses		(75)
Aggregate Estimated Fair Value		$ 30,508

DERIVATIVE FINANCIAL INSTRUMENTS - Additional Information (Details) - USD ($)			12 Months Ended				13 Months Ended
	Jan. 12, 2015	Nov. 13, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2014
Derivative [Line Items]
Interest expense, net			$ (1,188,000)	$ (759,000)	$ (7,748,000)
Grant date fair value of the Warrants recorded as a derivative liability (in dollars per share)						$ 2,500,000
Change in estimated fair value of liability classified warrants			$ 4,491,000	$ (1,655,000)	$ 33,307,000
Fair value of common stock (in dollars per share)			$ 21.07	$ 18.93
Warrants \| Derivative
Derivative [Line Items]
Total intrinsic value of derivative warrants outstanding and exercisable			$ 15,300,000
Credit Agreement
Derivative [Line Items]
Number of common stock called by warrants (in shares)					337,500	337,500
Exercise price (in dollars per share)						$ 12.76
Amendment No. 3 \| Definitive Agreement \| Athyrium Capital Management, LLC and Perceptive Credit Opportunities Fund, LP
Derivative [Line Items]
Credit agreement amount	$ 30,000,000
Number of common stock called by warrants (in shares)	125,000
Interest expense, net	$ 1,050,000
Note Payable With Detachable Warrants \| Clinuvel Pharmaceuticals Limited \| Amendment No. 2 \| Credit Agreement
Derivative [Line Items]
Number of common stock called by warrants (in shares)		300,000					300,000
Exercise price (in dollars per share)		$ 9.96
Value of common stock exercisable by warrants		$ 2,200,000					$ 2,200,000

DERIVATIVE FINANCIAL INSTRUMENTS - Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected dividend yield	0.00%	0.00%
Fair value of common stock (in dollars per share)	$ 21.07	$ 18.93
Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk free rate	1.39%	0.89%
Expected volatility	33.00%	55.00%
Expected life (in years), represents the weighted average period until next liquidity event	1 month 6 days	1 year 2 months 12 days
Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk free rate	1.89%	1.48%
Expected volatility	43.00%	75.00%
Expected life (in years), represents the weighted average period until next liquidity event	2 years	3 years
Warrants \| Derivative
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk free rate			1.39%	1.62%
Expected volatility			85.00%	85.00%
Expected life (in years), represents the weighted average period until next liquidity event			3 months 18 days	4 months 10 days
Expected dividend yield			0.00%	0.00%
Exercise Price (in dollars per share)			$ 13.25	$ 12.76

DERIVATIVE FINANCIAL INSTRUMENTS - Derivative Warrant Issuances (Details) - Warrants - Derivative - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Outstanding, Beginning Balance (in shares)	1,766,905	2,665,548	3,421,355
Issuance of common shares under the equity incentive plan (shares)	0	0	125,000
Canceled (in shares)	0	0	0
Exercised (in shares)	607,481	898,643	880,807
Outstanding, Ending Balance (in shares)	1,159,424	1,766,905	2,665,548
Weighted Average Exercise Price
Outstanding, Beginning Balance (in dollars per share)	$ 7.23	$ 7.05	$ 6.43
Issued (in dollars per share)	0.00	0.00	13.25
Cancelled (in dollars per share)	0.00	0.00	0.00
Exercised (in dollars per share)	6.00	6.68	5.35
Outstanding, Ending Balance (in dollars per share)	7.86	7.23	7.05
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in dollars per share)	3.87	4.20	3.79
Issued (in dollars per share)	0.00	0.00	8.40
Cancelled (in dollars per share)	0.00	0.00	0.00
Exercised (in dollars per share)	3.33	4.85	3.23
Outstanding, Ending Balance (in dollars per share)	$ 4.15	$ 3.87	$ 4.20

DERIVATIVE FINANCIAL INSTRUMENTS - Derivative Warrants Outstanding (Details) - Warrants - Derivative - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Warrants (in shares)	1,159,424	1,766,905	2,665,548	3,421,355
$3.60
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price (in dollars per share)	$ 3.60
Number of Warrants (in shares)	168,336
Weighted Average Remaining Contractual Life (years)	1 month 6 days
Number Exercisable (in shares)	168,336
$6.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price (in dollars per share)	$ 6.00
Number of Warrants (in shares)	611,921
Weighted Average Remaining Contractual Life (years)	7 months 6 days
Number Exercisable (in shares)	611,921
$12.76
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price (in dollars per share)	$ 12.76
Number of Warrants (in shares)	337,500
Weighted Average Remaining Contractual Life (years)	1 year 6 months
Number Exercisable (in shares)	337,500
$13.25
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price (in dollars per share)	$ 13.25
Number of Warrants (in shares)	41,667
Weighted Average Remaining Contractual Life (years)	2 years
Number Exercisable (in shares)	41,667

FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Asset:
Marketable securities, available-for-sale	$ 201,236	$ 214,871
Liabilities:
Derivative liability related to warrants	15,710	22,440
Recurring basis
Asset:
Cash and Cash Equivalents	99,394	41,002
Marketable securities, available-for-sale	201,236	214,871
Total	300,630	255,873
Liabilities:
Derivative liability related to warrants	15,710	22,440
Business combination-related contingent consideration	90,000	87,478
Total	105,710	109,918
Recurring basis \| Quoted prices in active markets (Level 1)
Asset:
Cash and Cash Equivalents	92,726	39,929
Marketable securities, available-for-sale	0	0
Total	92,726	39,929
Liabilities:
Derivative liability related to warrants	0	0
Business combination-related contingent consideration	0	0
Total	0	0
Recurring basis \| Significant other observable inputs (Level 2)
Asset:
Cash and Cash Equivalents	6,668	1,073
Marketable securities, available-for-sale	201,236	214,871
Total	207,904	215,944
Liabilities:
Derivative liability related to warrants	0	0
Business combination-related contingent consideration	0	0
Total	0	0
Recurring basis \| Significant unobservable inputs (Level 3)
Asset:
Cash and Cash Equivalents	0	0
Marketable securities, available-for-sale	0	0
Total	0	0
Liabilities:
Derivative liability related to warrants	15,710	22,440	$ 38,810
Business combination-related contingent consideration	90,000	87,478	$ 59,021
Total	$ 105,710	$ 109,918

FAIR VALUE MEASUREMENTS - Changes in Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	$ 22,440
Reclassification of derivative liability to equity upon exercise of warrants	(11,221)	$ (14,715)	$ (25,537)
Change in estimated fair value of liability classified warrants	4,491	(1,655)	33,307
Balance, ending	15,710	22,440
Recurring basis
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	22,440
Balance, ending	15,710	22,440
Recurring basis \| Significant unobservable inputs (Level 3)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning	22,440	38,810
Reclassification of derivative liability to equity upon exercise of warrants	(11,221)	(14,715)
Change in estimated fair value of liability classified warrants	4,491	(1,655)
Balance, ending	$ 15,710	$ 22,440	$ 38,810

FAIR VALUE MEASUREMENTS - Acquisition Related Contingent Consideration (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combination, Acquisition Related Contingent Consideration [Roll Forward]
Change in fair value of contingent consideration	$ 19,389	$ 18,383	$ 13,778
Recurring basis
Business Combination, Acquisition Related Contingent Consideration [Roll Forward]
Balance at January 1,	87,478
Balance at December 31,	90,000	87,478
Recurring basis \| Significant unobservable inputs (Level 3)
Business Combination, Acquisition Related Contingent Consideration [Roll Forward]
Balance at January 1,	87,478	59,021
Present value of contingent consideration upon acquisition related to a business combination	0	25,000
Change in fair value of contingent consideration	19,389	18,383
Contractual Payments	(6,006)	(12,826)
Contractual Payments accrued at December 31	(11,012)	(1,988)
Foreign currency impact	151	(112)
Balance at December 31,	$ 90,000	$ 87,478	$ 59,021

INTANGIBLE ASSETS - Additional Information (Details) - USD ($) $ in Thousands					1 Months Ended	12 Months Ended					48 Months Ended
	Nov. 03, 2017	Jun. 20, 2016	Mar. 31, 2015	May 29, 2014	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2017	Jun. 16, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets finite-lived, net						$ 159,317					$ 159,317
Payments to date under terms of licensing agreement						13,122	$ 10,496	$ 7,008
Impairment of intangible assets						$ 0	0	$ 4,710
Other Expense
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets					$ 4,700
Asklepion Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Discount rate percentage								19.00%
Total Purchase Price			$ 91,284
Economic Interest - L-UDCA (acquired IPR&D)
Finite-Lived Intangible Assets [Line Items]
Intangible assets with definite lives		$ 25,500
Assets useful life (in years)		17 years				17 years
Discount rate percentage		12.00%
Total Purchase Price		$ 25,500										$ 25,500
Ligand License Agreement
Finite-Lived Intangible Assets [Line Items]
Intangible assets finite-lived, net										$ 2,500
Require to make substantial payments payable upon achievement of milestones										$ 109,400
Payments to date under terms of licensing agreement											2,600
Payment of amendment consideration					$ 1,000
Ligand License Agreement \| Minimum
Finite-Lived Intangible Assets [Line Items]
Annual royalty percentage										15.00%
Ligand License Agreement \| Maximum
Finite-Lived Intangible Assets [Line Items]
Annual royalty percentage										17.00%
Product rights
Finite-Lived Intangible Assets [Line Items]
Intangible assets finite-lived, net						$ 51,873	$ 56,111				51,873
Intangible assets with definite lives									$ 67,849
Assets useful life (in years)						16 years	16 years
Finite-lived intangible asset						$ 67,849					67,849
Product rights \| Manchester Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Intangible assets with definite lives									$ 67,800
Assets useful life (in years)									16 years
Product rights \| Asklepion Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Assets useful life (in years)			10 years
Trade Name
Finite-Lived Intangible Assets [Line Items]
Intangible assets finite-lived, net						$ 0	$ 0				0
Assets useful life (in years)						1 year	1 year
Finite-lived intangible asset						$ 175	$ 175				175
Trade Name \| Manchester Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Intangible assets with definite lives									$ 200
Assets useful life (in years)									1 year
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets finite-lived, net						$ 251	$ 291				251
Assets useful life (in years)						10 years	10 years
Finite-lived intangible asset						$ 403	$ 403				403
Customer relationships \| Manchester Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Intangible assets with definite lives									$ 400
Assets useful life (in years)									10 years
Vecamyl
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset								$ 3,600
Thiola License Agreement
Finite-Lived Intangible Assets [Line Items]
Assets useful life (in years)									10 years
Automatic renewal periods									1 year
Remaining weighed average period of amortization (in years)						11 years 6 months
Thiola License Agreement \| Mission Pharmacal Company
Finite-Lived Intangible Assets [Line Items]
Annual royalty percentage				20.00%
Mission an up-front license fee				$ 3,000
Guaranteed minimum royalties				$ 2,000
Discount rate percentage						11.00%
Present value of guaranteed minimum royalties payable						$ 15,100	10,100				15,100
Royalty guarantees commitments, amount, current							2,000
Royalty guarantees commitments, amount, long-term							8,100
Thiola License Agreement \| Mission Pharmacal Company \| Other Current Liabilities
Finite-Lived Intangible Assets [Line Items]
Guaranteed minimum royalties						2,000					2,000
Thiola License Agreement \| Mission Pharmacal Company \| Other Noncurrent Liabilities
Finite-Lived Intangible Assets [Line Items]
Guaranteed minimum royalties						13,100					13,100
Thiola
Finite-Lived Intangible Assets [Line Items]
Intangible assets finite-lived, net						44,303	$ 29,521				44,303
Assets useful life (in years)							10 years
Finite-lived intangible asset	$ 5,900					$ 54,471	$ 35,339				$ 54,471
Licensing agreement, extension term	5 years
United States \| Asklepion Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Capitalized economic interest			$ 75,900
International \| Asklepion Pharmaceuticals LLC
Finite-Lived Intangible Assets [Line Items]
Capitalized economic interest			$ 7,300

INTANGIBLE ASSETS - Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014	Nov. 03, 2017
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (51,046)	$ (33,497)
Intangible assets finite-lived, net	159,317
Intangible assets, gross (excluding goodwill)	235,863	215,540
Intangible Assets, Net (Excluding Goodwill)	$ 184,817	$ 182,043
Chenodal Product Rights
Finite-Lived Intangible Assets [Line Items]
Useful Life	16 years	16 years
Intangible assets acquired with definite lives			$ 67,849
Finite-lived intangible asset, gross	$ 67,849
Accumulated Amortization	(15,976)	$ (11,738)
Intangible assets finite-lived, net	51,873	$ 56,111
Thiola License
Finite-Lived Intangible Assets [Line Items]
Useful Life		10 years
Finite-lived intangible asset, gross	54,471	$ 35,339		$ 5,900
Accumulated Amortization	(10,168)	(5,818)
Intangible assets finite-lived, net	$ 44,303	$ 29,521
Economic Interest - U.S. revenue Cholbam
Finite-Lived Intangible Assets [Line Items]
Useful Life	10 years	10 years
Finite-lived intangible asset, gross	$ 75,900	$ 75,900
Accumulated Amortization	(20,903)	(13,320)
Intangible assets finite-lived, net	$ 54,997	$ 62,580
Economic Interest - Int'l revenue Cholbam
Finite-Lived Intangible Assets [Line Items]
Useful Life	10 years	10 years
Finite-lived intangible asset, gross	$ 8,058	$ 7,074
Accumulated Amortization	(2,219)	(1,241)
Intangible assets finite-lived, net	5,839	5,833
Economic Interest - L-UDCA (acquired IPR&D)
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 25,500	$ 25,500
Ligand License
Finite-Lived Intangible Assets [Line Items]
Useful Life	11 years	11 years
Finite-lived intangible asset, gross	$ 3,300	$ 3,300
Accumulated Amortization	(1,420)	(1,093)
Intangible assets finite-lived, net	$ 1,880	$ 2,207
Manchester Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Useful Life	10 years	10 years
Finite-lived intangible asset, gross	$ 403	$ 403
Accumulated Amortization	(152)	(112)
Intangible assets finite-lived, net	$ 251	$ 291
Manchester Trade Name
Finite-Lived Intangible Assets [Line Items]
Useful Life	1 year	1 year
Finite-lived intangible asset, gross	$ 175	$ 175
Accumulated Amortization	(175)	(175)
Intangible assets finite-lived, net	$ 0	$ 0
Internal Use Software [Member]
Finite-Lived Intangible Assets [Line Items]
Useful Life	5 years
Finite-lived intangible asset, gross	$ 207
Accumulated Amortization	(33)
Intangible assets finite-lived, net	$ 174
Manchester Pharmaceuticals LLC \| Chenodal Product Rights
Finite-Lived Intangible Assets [Line Items]
Useful Life			16 years
Intangible assets acquired with definite lives			$ 67,800
Manchester Pharmaceuticals LLC \| Manchester Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Useful Life			10 years
Intangible assets acquired with definite lives			$ 400
Manchester Pharmaceuticals LLC \| Manchester Trade Name
Finite-Lived Intangible Assets [Line Items]
Useful Life			1 year
Intangible assets acquired with definite lives			$ 200

INTANGIBLE ASSETS - Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 17,331	$ 15,993	$ 13,231
Research and development
Finite-Lived Intangible Assets [Line Items]
Amortization expense	327	328	697
Selling, general and administrative
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 17,004	$ 15,665	$ 12,534

INTANGIBLE ASSETS - Amortization Expense Next Five Years (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2018	$ 16,871
2019	16,871
2020	16,871
2021	16,871
2022	16,871
Thereafter	74,962
Intangible assets finite-lived, net	$ 159,317

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Compensation related costs	$ 7,749	$ 7,441
Research and development	6,989	7,311
Government rebate reserves	5,883	6,967
Selling, general and administrative	3,896	3,333
Royalty/contingent consideration	6,429	5,766
Restructuring reserve	3,549	893
Miscellaneous accrued expenses	1,523	1,597
Total accrued expenses	$ 36,018	$ 33,308

NOTES PAYABLE - Convertible Notes Payable (Details) - USD ($)		12 Months Ended
	Jun. 30, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	May 29, 2014
Debt Instrument [Line Items]
Finance expense as other expense related to issuance		$ 0	$ 0	$ 600,000
Convertible debt (in shares)		0	0	2,642,160
Convertible Debt \| Note Purchase Agreement
Debt Instrument [Line Items]
Credit agreement amount						$ 46,000,000
Initial conversion price (in dollars per share)						$ 17.41
Interest rate percentage						4.50%
Aggregate carrying value						$ 43,000,000
Debt discount						$ 3,000,000
Issuance of common stock, net of fees (in shares)	401,047
Finance expense as other expense related to issuance					$ 4,700,000
Fair value of common stock (in dollars per share)		$ 21.07
Convertible debt (in shares)		2,642,160
If-converted value in excess of carrying amount		$ 10,500,000
Fair value of convertible debt		$ 63,600,000

NOTES PAYABLE - Schedule of Carrying Amount of Debt (Details) - Convertible Debt - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Aggregate principle amount of Notes	$ 46,000	$ 46,000
Unamortized debt discount and debt issuance costs	(923)	(1,578)
Net carrying amount	$ 45,077	$ 44,422

NOTES PAYABLE - Credit Facility (Details) - USD ($)					1 Months Ended	12 Months Ended				13 Months Ended
NOTES PAYABLE - Credit Facility (Details) - USD ($)	Jul. 01, 2015	Mar. 24, 2015	Jan. 12, 2015	Nov. 13, 2014	Jun. 30, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2014
Line of Credit Facility [Line Items]
Grant date fair value of the Warrants recorded as a derivative liability (in dollars per share)									$ 2,500,000
Issuance of common stock in connection with public offering, net of fees								$ 139,987,000
Interest expense						$ 1,200,000	$ 800,000	$ 7,700,000
Credit Facility
Line of Credit Facility [Line Items]
Number of common stock called by warrants (in shares)			125,000
Cash payment to Lenders			$ 600,000
Value of warrant or right number of securities called by warrants or rights			1,100,000
Issuance of common stock in connection with public offering, net of fees		$ 140,000,000
Payment due to Asklepion upon closing			27,000,000
Prepayment premium	$ 2,300,000
Additional charge of prepayment premium	$ 4,200,000
Credit Agreement
Line of Credit Facility [Line Items]
Number of common stock called by warrants (in shares)								337,500	337,500
Exercise price (in dollars per share)									$ 12.76
Credit Agreement \| Convertible Notes Payable
Line of Credit Facility [Line Items]
Credit agreement amount					$ 45,000,000
LIBOR Rate \| Credit Agreement \| Convertible Notes Payable
Line of Credit Facility [Line Items]
Debt instrument basis points added percentage					10.00%
Base Rate \| Credit Agreement \| Convertible Notes Payable
Line of Credit Facility [Line Items]
Debt instrument basis points added percentage					9.00%
Amendment No. 3 \| Definitive Agreement \| Athyrium Capital Management, LLC and Perceptive Credit Opportunities Fund, LP
Line of Credit Facility [Line Items]
Credit agreement amount			$ 30,000,000
Number of common stock called by warrants (in shares)			125,000
Clinuvel Pharmaceuticals Limited \| Amendment No. 2 \| Credit Agreement \| Note Payable With Detachable Warrants
Line of Credit Facility [Line Items]
Number of common stock called by warrants (in shares)				300,000						300,000
Exercise price (in dollars per share)				$ 9.96
Value of common stock exercisable by warrants				$ 2,200,000						$ 2,200,000

NOTES PAYABLE - Fair Value of Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Debt Instrument [Line Items]
Expected dividend yield	0.00%	0.00%
Note Payable With Detachable Warrants
Debt Instrument [Line Items]
Risk free rate			1.62%
Expected volatility			85.00%
Expected life (in years), represents the weighted average period until next liquidity event			4 months 10 days
Expected dividend yield			0.00%
Exercise Price (in dollars per share)			$ 12.76

COMMITMENTS AND CONTINGENCIES - Leases and Sublease Agreements (Details) - Leases and Sublease Agreements	12 Months Ended
	Dec. 31, 2017 USD ($)
Corporate Headquarters San Diego CA
Other Commitments [Line Items]
Annual base rent	$ 2,100,000.0
New York NY
Other Commitments [Line Items]
Annual base rent	$ 500,000.0

COMMITMENTS AND CONTINGENCIES - Contractual Commitments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Operating leases
Operating leases	$ 16,037
Less than 1 year	2,012
1-3 years	4,757
3-5 years	5,046
More than 5 years	4,222
Purchase order commitments
Purchase order commitments	8,119
Less than 1 year	5,619
1-3 years	1,000
3-5 years	1,000
More than 5 years	500
Total
Total	100,266
Less than 1 year	13,476
1-3 years	57,634
3-5 years	10,879
More than 5 years	18,277
Note payable, including contractual interest
Other Commitments
Other commitments	71,933
Less than 1 year	4,070
1-3 years	50,863
3-5 years	4,000
More than 5 years	13,000
Sales support services
Other Commitments
Other commitments	2,638
Less than 1 year	417
1-3 years	833
3-5 years	833
More than 5 years	555
Product supply contracts
Other Commitments
Other commitments	1,539
Less than 1 year	1,358
1-3 years	181
3-5 years	0
More than 5 years	$ 0

COMMITMENTS AND CONTINGENCIES - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		2 Months Ended	12 Months Ended
	Dec. 31, 2017	Nov. 30, 2016	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Commitments [Line Items]
Legal fee settlement				$ 2,625	$ 5,212	$ 0
Legal fee judgment				2,025
Martin Shkreli
Other Commitments [Line Items]
Legal fees paid In advance		$ 2,800
Contingent future legal fee advance payment			$ 2,000
Legal fees reimbursed from director and officer insurance carriers			$ 3,300	2,600	700
Legal fees paid				$ 3,600	$ 1,000
Retrophin, Inc. v. Shkreli, \| Martin Shkreli
Other Commitments [Line Items]
Legal fees paid In advance	$ 600					$ 400

STOCKHOLDERS’ EQUITY / DEFICIT - Common Stock and Preferred Stock (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares
Class of Stock [Line Items]
Common stock, shares authorized (in shares) \| shares	100,000,000	100,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Number of votes per common share owned	1
Preferred Stock, shares authorized (in shares) \| shares	20,000,000	20,000,000
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.001	$ 0.001
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, shares authorized (in shares) \| shares	1,000
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.001

STOCKHOLDERS’ EQUITY / DEFICIT - Public Offering 2015 (Details) - USD ($)		1 Months Ended	12 Months Ended
	Mar. 24, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock, per share amount (in dollars per share)		$ 19.00
Proceeds received from issuance of common stock			$ 0	$ 0	$ 149,487,000
Underwriting fees and other offering costs		$ 9,181,991
Common Stock
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock, net of fees (in shares)					7,866,000
Common Stock \| Public Offering
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock, net of fees (in shares)	7,866,000
Issuance of common stock, per share amount (in dollars per share)	$ 19.00
Proceeds received from issuance of common stock	$ 140,000,000
Underwriting fees and other offering costs	$ 9,500,000

STOCKHOLDERS’ EQUITY / DEFICIT - 2015 Equity Incentive Plan (Details) - shares	May 18, 2016	Dec. 31, 2017	May 17, 2017	Dec. 31, 2016	Jun. 08, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (in shares)		100,000,000		100,000,000
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (in shares)					1,400,000.0
Shares remaining available for issuance under the plan (in shares)					600,000.0
2015 Equity Incentive Plan Amended
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (in shares)	1,600,000.0		1,800,000.0
Shares remaining available for issuance under the plan (in shares)	700,000.0
Options \| 2015 Equity Incentive Plan Amended
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, reduction in number of shares available for grant	100.00%
Restricted Stock \| 2015 Equity Incentive Plan Amended
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, reduction in number of shares available for grant	200.00%

STOCKHOLDERS’ EQUITY / DEFICIT - 2017 Employee Stock Purchase Plan (Details) - 2017 ESPP	12 Months Ended
	Dec. 31, 2017 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares remaining available for issuance under the plan (in shares) \| shares	380,000.000
Potential increase in shares available for issuance, as a percent of total outstanding common stock	1.00%
Maximum number of additional shares authorized for issuance (in shares) \| shares	300,000
Purchase price of common stock, percent of fair market value	85.00%
Stock purchase offering period	6 months
Employee Stock Purchase Plan, Maximum Compensation	15.00%
Employee Stock Purchase Plan Annual Limit \| $	$ 25,000
Shares reserved for future issuance (in shares) \| $	$ 300,000

STOCKHOLDERS’ EQUITY / DEFICIT - Black Scholes Assumptions (Details) - Stock Options - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	2,111,300	1,687,250	2,285,000
Risk free rate	2.10%	1.20%	1.53%
Expected volatility	70.00%	68.00%	83.00%
Expected life (in years)	6 years 1 month 6 days	5 years 9 months 18 days	5 years 9 months 22 days
Expected dividend yield	0.00%	0.00%	0.00%

STOCKHOLDERS’ EQUITY / DEFICIT - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Closing stock price of stock options outstanding and exercisable (in dollars per share)	$ 21.07	$ 18.93
Stock Options
Shares
Exercisable beginning balance (in shares)	3,793,017	2,036,906	1,225,833
Outstanding, Beginning Balance (in shares)	6,430,570	5,665,584	4,892,208
Granted (in shares)	2,111,300	1,687,250	2,285,000
Forfeited and expired (in shares)	(759,127)	(541,416)	(970,170)
Exercised (in shares)	(629,075)	(380,848)	(541,454)
Outstanding, Ending Balance (in shares)	7,153,668	6,430,570	5,665,584	4,892,208
Exercisable ending balance (in shares)	4,610,233	3,793,017	2,036,906	1,225,833
Weighted Average Exercise Price
Exercisable beginning balance (in dollars per share)	$ 14.94	$ 12.55	$ 9.73
Outstanding, Beginning Balance (in dollars per share)	16.91	17.05	10.93
Granted (in dollars per share)	18.48	16.73	27.15
Forfeited and expired (in dollars per share)	22.28	22.19	14.91
Exercised (in dollars per share)	12.86	10.55	13.10
Outstanding, Ending Balance (in dollars per share)	17.16	16.91	17.05	$ 10.93
Exercisable ending balance (in dollars per share)	$ 15.97	$ 14.94	$ 12.55	$ 9.73
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Remaining Contractual Term, Exercisable (in years)	5 years 10 months 6 days	6 years 9 months 26 days	8 years 4 months 2 days	7 years 11 months 16 days
Remaining Contractual Term, Outstanding (in years)	6 years 11 months 12 days	7 years 7 months 21 days	8 years 9 months	8 years 6 months 25 days
Exercisable, Aggregate Intrinsic Value	$ 31,991	$ 23,358	$ 15,582	$ 3,395
Outstanding, Aggregate Intrinsic Value	39,010	30,088	31,542	$ 8,353
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 5,420	$ 2,873	$ 7,230
Weighted average grant date fair value of options (in dollars per share)	$ 11.77	$ 10.09	$ 19.02
Compensation expense not yet recognized, stock options	$ 27,900
Weighted average period for unrecognized costs (in years)	2 years 7 months 6 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average period for unrecognized costs (in years)	1 year 7 months 6 days

STOCKHOLDERS’ EQUITY / DEFICIT - Unvested Restricted Stock (Details) - Restricted shares - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to restricted shares granted	$ 2.3
Weighted average period for unrecognized costs (in years)	1 year 7 months 6 days
Number of shares
Unvested beginning balance (in shares)	407,746	429,666
Granted (in shares)	157,750	245,000
Vested (in shares)	(190,498)	(161,335)
Forfeited/cancelled (in shares)	(29,666)	(105,585)
Unvested ending balance (in shares)	345,332	407,746
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share)	$ 19.88	$ 20.38
Granted (in dollars per share)	18.32	17.52
Vested (in dollars per share)	17.12	16.76
Forfeited/cancelled (in dollars per share)	22.00	21.19
Unvested ending balance (in dollars per share)	$ 20.51	$ 19.88

STOCKHOLDERS’ EQUITY / DEFICIT - Share Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 26,874	$ 29,102	$ 25,900
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	17,924	18,614	16,483
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 8,950	$ 10,488	$ 9,417

STOCKHOLDERS’ EQUITY / DEFICIT - Exercise of Warrants (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds exercise of warrants	$ 3,645	$ 6,005	$ 4,475
Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock called by warrants (in shares)	607,481	898,633	870,306
Proceeds exercise of warrants	$ 3,600	$ 6,000	$ 4,500
Reclassification of derivative liability as equity	11,200	14,700	23,500
Change in fair value of warrants	$ 3,000	$ 2,900	$ 2,800

STOCKHOLDERS’ EQUITY / DEFICIT - Treasury Stock (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Value of shares repurchased during the period				$ 3.2
Common Stock
Equity, Class of Treasury Stock [Line Items]
Retirement of treasury stock (in shares)	379,591			379,591
Shares repurchased during the period (in shares)		0	0

EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Basic Earnings per Share (in shares)									38,769,816	36,997,865	33,560,249
Dilutive Earnings per Share (in shares)									38,769,816	38,288,012	37,581,439
Change in fair value of derivative instruments (in shares)									0	0	0
Convertible Debt (in shares)									0	0	2,642,160
Net loss
Net loss	$ (18)	$ (18)	$ (13)	$ (11)	$ (8,603)	$ (37,113)	$ (13,403)	$ 11,216	$ (59,731)	$ (47,903)	$ 117,237
Change in fair value of derivative instruments									0	(1,655)	0
Convertible Debt									0	0	1,881
Dilutive Earnings per Share									$ (59,731)	$ (49,558)	$ 119,118
Net income (loss) per common share, basic (in dollars per shares)	$ (0.45)	$ (0.46)	$ (0.34)	$ (0.29)	$ (0.23)	$ (1.00)	$ (0.37)	$ 0.31	$ (1.54)	$ (1.29)	$ 3.49
Net income (loss) per common share, diluted (in dollars per shares)	$ (0.55)	$ (0.46)	$ (0.34)	$ (0.32)	$ (0.39)	$ (1.00)	$ (0.37)	$ (0.08)	$ (1.54)	$ (1.29)	$ 3.17
Warrants
Shares
Dilutive Earnings per Share (in shares)									0	1,290,147	0
Restricted Stock
Shares
Dilutive securities (in shares)									0	0	290,966
Net loss
Dilutive securities									$ 0	$ 0	$ 0
Stock Options
Shares
Dilutive securities (in shares)									0	0	1,088,064
Net loss
Dilutive securities									$ 0	$ 0	$ 0

EARNINGS (LOSS) PER SHARE - Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	11,039,901	9,373,686	3,736,992
Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	2,642,160	2,642,160	0
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	157,319	444,942	22,069
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	7,080,998	6,286,584	1,049,375
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation (in shares)	1,159,424	0	2,665,548

INCOME TAXES - Components of Net Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Loss before provision for income taxes	$ (11)	$ (19)	$ (15)	$ (13)	$ (12,287)	$ (30,646)	$ (20,795)	$ 6,146	$ (58,363)	$ (57,582)	$ 105,467
United States
Operating Loss Carryforwards [Line Items]
Loss before provision for income taxes									(55,611)	(52,750)	107,038
Foreign
Operating Loss Carryforwards [Line Items]
Loss before provision for income taxes									$ (2,752)	$ (4,832)	$ (1,571)

INCOME TAXES - Components of Income Tax Expense(Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal									$ 6,991	$ 13,137	$ 2,094
State									802	(155)	1,709
Total									7,793	12,982	3,803
Deferred
Federal									(7,965)	(18,814)	(8,296)
State									1,540	(3,847)	(7,277)
Total									(6,425)	(22,661)	(15,573)
Total tax provision (benefit)	$ 7	$ (1)	$ (2)	$ (2)	$ (3,684)	$ 6,467	$ (7,392)	$ (5,070)	$ 1,368	$ (9,679)	$ (11,770)

INCOME TAXES - Reconciliation of Federal Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory rate - federal	35.00%	35.00%	35.00%
State taxes, net of federal benefit	3.30%	3.16%	1.53%
Change in FV of derivative liability (warrants)	(2.82%)	(1.10%)	10.89%
Change in federal tax rate	(23.29%)	0.00%	0.00%
Bargain purchase gain	0.00%	0.00%	(16.04%)
Other permanent differences	(1.04%)	(2.05%)	3.68%
Tax credits	5.79%	1.58%	(7.85%)
Return to provision adjustments and other true-ups	3.48%	1.15%	(10.40%)
Other	(1.25%)	(3.09%)	(0.79%)
Change in valuation allowance	(21.62%)	(16.30%)	(27.02%)
Income tax provision (benefit)	(2.45%)	18.35%	(11.00%)

INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets:
Net operating loss	$ 1,099	$ 1,832
Research and development and other tax credits	1,599	60
Contingent consideration	23,080	32,792
Other accrued expenses	2,603	4,621
Stock based compensation	15,695	18,520
Other	358	30
Deferred tax assets	44,434	57,855
Deferred Tax Liabilities:
Intangible assets	(16,810)	(34,153)
Deferred gain on installment sale	0	(14,547)
Tax basis depreciation less than book depreciation	0	0
Deferred tax liabilities	(16,810)	(48,700)
Net deferred tax assets (liabilities) before valuation allowance	27,624	9,155
Valuation allowance	(27,624)	(15,580)
Total deferred tax liability	$ 0	$ (6,425)

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 27,624	$ 15,580
Increase in valuation allowance primarily attributable to Tax and Jobs Act of 2017	12,000
Tax Cuts and Jobs Act of 2017, income tax expense	13,000
U.S. federal
Operating Loss Carryforwards [Line Items]
Available unused NOL carryforwards	5,200
Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credits	20
General Business Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development tax credits	$ 2,000

INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1:	$ 1,500	$ 3,324
Increase in current period positions	0	0
Decrease in prior period positions	(1,500)	(1,824)
Increase in prior period positions	0	0
Balance as of December 31:	$ 0	$ 1,500

RETIREMENT PLAN (Details) - USD ($)	12 Months Ended
RETIREMENT PLAN (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Defined contribution plan, employer contributions	$ 600,000	$ 500,000	$ 0

SEGMENT INFORMATION - Narrative (Details)	12 Months Ended
SEGMENT INFORMATION - Narrative (Details)	Dec. 31, 2017 segment
Segment Reporting [Abstract]
Number of segments	1

SEGMENT INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
SEGMENT INFORMATION (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net product sales	$ 42	$ 40	$ 39	$ 34	$ 37,327	$ 33,945	$ 33,311	$ 29,008	$ 154,937	$ 133,591	$ 99,892
Thiola
Segment Reporting Information [Line Items]
Net product sales									82,311	71,199	54,923
Bile Acid Products
Segment Reporting Information [Line Items]
Net product sales									$ 72,626	$ 62,392	$ 44,969

RESTRUCTURING (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
RESTRUCTURING (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2018
Restructuring Reserve [Roll Forward]
Liability, beginning of period		$ 893
Restructuring expenses		3,608	$ 893	$ 0
Cash settlements		(897)
Adjustments to previous estimates	$ (55)
Liability, end of period		3,549	893
Restructuring reserve		$ 893	$ 893
Subsequent Event
Restructuring Reserve [Roll Forward]
Restructuring reserve					$ 300

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 500	$ 100	$ 100
Property, Plant and Equipment, Gross	3,815	2,787
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(585)	(200)
Property, Plant and Equipment, Net	3,230	2,587
Computers and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	436	311
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	945	1,573
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,071	903
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 363	$ 0

SUBSEQUENT EVENTS (Details) - Subsequent Event $ / shares in Units, $ in Millions	Jan. 08, 2018 USD ($) $ / shares
Subsequent Event [Line Items]
Option agree to purchase a business, transaction price	$ 65
Option agree to purchase a business, percent required to be paid in cash	20.00%
Option agree to purchase a business, percent required to be paid via the issuance of equity	80.00%
Option to acquire a business, share price of stock issued (in usd per share) \| $ / shares	$ 21.40
Percent of payments to acquire a business, if stock price falls below stated threshold	100.00%
Ten day weighted average share price, after option is executed, threshold to trigger all cash payment \| $ / shares	$ 19.26
Option to purchase a business, contingent consideration for achievement of developmental milestones	$ 25
Censa Pharmaceuticals Inc. \| CNSA-001 Program \| Purchase Provision Terms
Subsequent Event [Line Items]
Agreed amount to be funded for certain development activities	16
Censa Pharmaceuticals Inc.
Subsequent Event [Line Items]
Payments for the option to acquire business	10
Censa Pharmaceuticals, Inc, Equity Holders
Subsequent Event [Line Items]
Payments for the option to acquire business	9
Additional required payments for the option to acquire business, after successful development milestones	$ 5

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net product sales	$ 42	$ 40	$ 39	$ 34	$ 37,327	$ 33,945	$ 33,311	$ 29,008	$ 154,937	$ 133,591	$ 99,892
Total operating expenses	57	51	52	48	55,549	54,317	44,690	37,249	208,728	191,805	150,640
Operating loss	(15)	(11)	(14)	(14)	(18,222)	(20,372)	(11,379)	(8,241)	(53,791)	(58,214)	(50,748)
Total other income (expense), net	4	(8)	(2)	1	(5,935)	10,274	9,416	(14,387)	(4,572)	632	156,215
Loss before provision for income taxes	(11)	(19)	(15)	(13)	(12,287)	(30,646)	(20,795)	6,146	(58,363)	(57,582)	105,467
Income tax benefit (provision)	(7)	1	2	2	3,684	(6,467)	7,392	5,070	(1,368)	9,679	11,770
Net income (loss)	$ (18)	$ (18)	$ (13)	$ (11)	$ (8,603)	$ (37,113)	$ (13,403)	$ 11,216	$ (59,731)	$ (47,903)	$ 117,237
Net Loss per common share
Net income (loss) per common share, basic (in dollars per shares)	$ (0.45)	$ (0.46)	$ (0.34)	$ (0.29)	$ (0.23)	$ (1.00)	$ (0.37)	$ 0.31	$ (1.54)	$ (1.29)	$ 3.49
Net income (loss) per common share, diluted (in dollars per shares)	$ (0.55)	$ (0.46)	$ (0.34)	$ (0.32)	$ (0.39)	$ (1.00)	$ (0.37)	$ (0.08)	$ (1.54)	$ (1.29)	$ 3.17