Hyperion Therapeutics (HPTX) 10-Q 7 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	5-May-14
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'HPTX	'
Entity Registrant Name	'HYPERION THERAPEUTICS INC	'
Entity Central Index Key	'0001386858	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	20,264,243

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$79,783	$74,232
Short-term investments	40,861	28,045
Accounts receivable, net	2,354	4,419
Inventories	2,825	3,513
Prepaid expenses and other current assets	1,101	1,403
Total current assets	126,924	111,612
Long-term investments	3,865	15,780
Property and equipment, net	862	936
Intangible asset, net	12,428	13,442
Other non-current assets	741	749
Total assets	144,820	142,519
Current liabilities	'	'
Accounts payable	3,039	2,292
Accrued liabilities	10,995	12,187
Deferred revenue	195	'
Notes payable, current portion	5,779	5,652
Total current liabilities	20,008	20,131
Notes payable, net of current portion	1,258	2,621
Deferred rent	261	81
Total liabilities	21,527	22,833
Commitments and contingencies (Note 12)	'	'
Stockholders' equity	'	'
Preferred stock, par value $0.0001 - 10,000,000 shares authorized at March 31, 2014 and December 31, 2013; none issued and outstanding	'	'
Common stock, par value $0.0001 - 100,000,000 shares authorized at March 31, 2014 and December 31, 2013; 20,259,011 and 20,137,145 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	2	2
Additional paid-in capital	244,412	242,109
Accumulated other comprehensive loss	-10	-55
Accumulated deficit	-121,111	-122,370
Total stockholders' equity	123,293	119,686
Total liabilities and stockholders' equity	$144,820	$142,519

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]	'	'
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	20,259,011	20,137,145
Common stock, shares outstanding	20,259,011	20,137,145

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]	'	'
Net product revenue	$19,483	$783
Costs and expenses:	'	'
Cost of sales	2,382	68
Research and development	3,217	1,849
Selling, general and administrative	11,171	7,934
Amortization of intangible asset	1,014	'
Total costs and expenses	17,784	9,851
Income (loss) from operations	1,699	-9,068
Interest income	138	1
Interest expense	-300	-408
Other income (expense), net	-190	500
Income (loss) before income taxes	1,347	-8,975
Income tax expense	88	'
Net income (loss)	$1,259	($8,975)
Net income (loss) per share:	'	'
Basic	$0.06	($0.52)
Diluted	$0.06	($0.52)
Weighted average number of shares used to compute net income (loss) per share of common stock:	'	'
Basic	20,191,190	17,366,848
Diluted	21,518,526	17,366,848

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'
Net income (loss)	$1,259	($8,975)
Other comprehensive income:	'	'
Unrealized gain on investments arising during the period	45	'
Other comprehensive income	45	'
Comprehensive income (loss)	$1,304	($8,975)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities	'	'
Net income (loss)	$1,259	($8,975)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities	'	'
Depreciation and amortization	103	19
Amortization of debt discount and debt issuance cost	139	137
Stock-based compensation expense	1,366	505
Amortization of intangible asset	1,014	'
Amortization of discount on available-for-sale investments	104	'
Excess tax benefit from stock-based compensation	-44	'
Changes in assets and liabilities	'	'
Accounts receivable	2,065	-819
Inventories	696	-464
Prepaid expenses and other current assets	302	75
Accounts payable	747	-834
Deferred revenue	195	'
Accrued liabilities	-1,150	-396
Deferred rent	180	'
Net cash provided by (used in) operating activities	6,976	-10,752
Cash flows from investing activities	'	'
Acquisition of property and equipment	-29	-315
Purchase of available-for-sale investments	-1,440	'
Maturity of available-for-sale investments	480	'
Net cash used in investing activities	-989	-315
Cash flows from financing activities	'	'
Proceeds from issuance of common stock in follow-on offering, net of underwriting discounts	'	64,488
Proceeds from issuance of common stock from stock option exercises	887	91
Excess tax benefit from stock-based compensation	44	'
Payments of offering costs	'	-23
Principal payments under notes payable	-1,367	-676
Net cash provided by (used in) financing activities	-436	63,880
Net increase in cash and cash equivalents	5,551	52,813
Cash and cash equivalents, beginning of period	74,232	49,853
Cash and cash equivalents, end of period	79,783	102,666
Supplemental cash flow information	'	'
Cash paid for interest	171	275
Supplemental disclosure of noncash investing and financing activities	'	'
Stock-based compensation capitalized into inventories	8	9
Deferred offering costs in accounts payable and accrued liabilities	'	$753

Formation_and_Business_of_the_

Formation and Business of the Company	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Formation and Business of the Company	'
	1. Formation and Business of the Company
	Hyperion Therapeutics, Inc. (the “Company”) was incorporated in the state of Delaware on November 1, 2006. The Company was in the development stage from inception through March 31, 2013. During this period, the Company’s activities consisted primarily of raising capital, negotiating a promotion and drug development collaboration agreement, establishing a management team and performing drug development activities. The Company launched RAVICTI® (glycerol phenylbutyrate) Oral Liquid during the quarter ended March 31, 2013 and acquired BUPHENYL® (sodium phenylbutyrate) Tablets and Powder in May 2013.
	The Company is a commercial stage biopharmaceutical company focused on the development and commercialization of novel therapeutics to treat disorders in the area of orphan diseases. The Company has developed RAVICTI to treat 7 of the 8 most prevalent subtypes of urea cycle disorders (“UCD”) and is developing glycerol phenylbutyrate (“GPB”) for the potential treatment of hepatic encephalopathy (“HE”). UCD and HE are generally characterized by elevated levels of ammonia in the bloodstream. Elevated levels of ammonia are potentially toxic and can lead to severe medical complications which may include death. The Company’s product, RAVICTI, is designed to lower ammonia in the blood. UCD are inherited rare genetic diseases caused by a deficiency of one or more enzymes or transporters that constitute the urea cycle, which in a healthy individual removes ammonia through conversion of ammonia to urea. HE is a serious but potentially reversible neurological disorder that can occur in patients with liver scarring, known as cirrhosis, or acute liver failure. On February 1, 2013, the U.S. Food and Drug Administration (“FDA”), granted approval of RAVICTI for the use as a nitrogen-binding agent for chronic management of adult and pediatric UCD patients greater than two years of age who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. On May 31, 2013, the Company acquired BUPHENYL, an FDA-approved therapy for treatment of 3 of the most prevalent UCD subtypes, from Ucyclyd Pharma Inc. (“Ucyclyd”), a subsidiary of Valeant Pharmaceuticals International, Inc. (“Valeant”). Subsequent to the acquisition on May 31, 2013, the Company started selling BUPHENYL Tablets and Powder within and outside the United States.
	Hyperion Therapeutics Limited was formed in January 2008 as a private limited company under the Companies Act 1985 for England and Wales and is wholly owned by the Company. Since formation, there has been no activity in Hyperion Therapeutics Limited.
	On March 13, 2013, the Company completed its follow-on offering. The Company received net proceeds from the offering of $63.7 million, after deducting underwriting discounts and commissions of $4.1 million and expenses of $0.8 million.
	On August 14, 2013, the Company filed a shelf registration statement on Form S-3, which was declared effective by the Securities and Exchange Commission (“SEC”) on September 13, 2013. The shelf registration statement permits: (a) the offering, issuance and sale by the Company of up to a maximum aggregate offering price of $150.0 million of its common stock, preferred stock, debt securities, warrants and/or units; (b) the sale of up to 8,727,000 shares of common stock by certain selling stockholders; and (c) the offering, issuance and sale by the Company of up to a maximum aggregate offering price of $50.0 million of its common stock that may be issued and sold under a sales agreement with Cantor Fitzgerald & Co. As of March 31, 2014, there were no sales of any securities registered pursuant to the shelf registration statement.
	At March 31, 2014, the Company had an accumulated deficit of $121.1 million. The Company expects to incur increased research and development expenses when the Company initiates a Phase III trial of GPB for the treatment of patients with episodic HE. In addition, the Company expects to incur increased sales and marketing expenses with the continued commercialization of RAVICTI and marketing of BUPHENYL in UCD. Management’s plans with respect to these matters include utilizing a substantial portion of the Company’s capital resources and efforts in completing the development and obtaining regulatory approval of GPB in HE, expanding the Company’s organization, and commercialization of RAVICTI and marketing of BUPHENYL.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	Basis of Presentation
	The accompanying interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and on a basis consistent with the annual consolidated financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the periods presented. These interim financial results are not necessarily indicative of the results to be expected for the year ending December 31, 2014, or for any other future annual or interim period. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
	Use of Estimates
	The preparation of the interim condensed consolidated financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to fair value of assets and liabilities, intangible asset valuation, stock-based compensation expense, income taxes, revenue recognition and product sales allowances. Management bases its estimates on historical experience or on various other assumptions, including information received from its service providers, which it believes to be reasonable under the circumstances. Actual results could differ from those estimates.
	Segment Reporting
	The Company operates as one operating segment and uses one measurement of profitability to manage its business. All long-lived assets are maintained in the United States. For the three months ended March 31, 2014, net product revenue in the United States and rest of the world (primarily Canada and Europe) was $18.0 million and $1.5 million, respectively. For the three months ended March 31, 2014, net product revenue consisted of net sales from RAVICTI of $15.5 million and net sales from BUPHENYL of $4.0 million. For the three months ended March 31, 2013, net product revenue for RAVICTI in the United States was $0.8 million.
	Concentration of Credit Risk and Significant customers
	The Company’s cash and cash equivalents and investments are maintained with financial institutions located in the United States. Deposits in these institutions may exceed the amount of insurance provided on such deposits. The Company has not recognized any losses from credit risks during the periods presented and management does not believe that the Company is exposed to significant credit risk from its cash and cash equivalents or investments.
	The Company is also subject to credit risk from its accounts receivables related to its product sales. The Company monitors its exposure within accounts receivable and records a reserve against uncollectible accounts receivable as necessary. The Company extends credit to a specialty distributor in the United States and to international distributors, pharmacies and hospitals outside the United States. Customer creditworthiness is monitored and collateral is not required. As of March 31, 2014, there were no credit losses on the Company’s accounts receivable. As of March 31, 2014, the specialty distributor in the United States accounted for 64% of the accounts receivable balance and one international distributor accounted for 12% of the accounts receivable balance.
	Fair Value of Financial Instruments
	The Company measures certain financial assets and liabilities at fair value based on the exchange price that would be received for an asset or paid for to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. The carrying amounts of the Company’s financial instruments, including cash equivalents, short-term investments, the option to purchase BUPHENYL and AMMONUL (Note 3), accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of long-term investments represent their estimated fair values. The Company’s debt obligations are carried at historical cost, which approximates fair value.
	Business Combinations
	The Company allocates the purchase price of an acquired business to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. Any excess of the purchase price over the fair value of the net assets acquired is recorded as goodwill. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets. Direct transaction costs associated with the business combination are expensed as incurred.
	Accounts Receivable
	Trade accounts receivable are recorded net of product sales allowances for prompt-payment discounts, chargebacks, and doubtful accounts. Estimates for chargebacks and prompt-payment discounts are based on contractual terms, historical trends and expectations regarding the utilization rates for these programs. At March 31, 2014, the Company had no allowances for doubtful accounts.
	Inventories
	Inventories are stated at the lower of cost or market value with cost determined under the first-in-first-out (FIFO) cost method and consists of raw materials, work-in-progress and finished goods. Costs to be capitalized as inventories include third party manufacturing costs, associated compensation related costs of personnel indirectly involved in the manufacturing process and other overhead costs such as ancillary supplies. Subsequent to FDA approval of RAVICTI on February 1, 2013, the Company began capitalizing RAVICTI inventories as the related costs were expected to be recoverable through the commercialization of the product. Costs incurred prior to the FDA approval of RAVICTI have been recorded as research and development expense in the condensed consolidated statements of operations. If information becomes available that suggest that inventories may not be realizable, the Company may be required to expense a portion or all of the previously capitalized inventories.
	Products that have been approved by the FDA or other regulatory authorities, such as RAVICTI, are also used in clinical programs, to assess the safety and efficacy of the products for usage in diseases that have not been approved by the FDA or other regulatory authorities. The form of RAVICTI utilized for both commercial and clinical programs is identical and, as a result, the inventory has an “alternative future use” as defined in authoritative guidance. Raw materials and purchased drug product associated with clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes and, therefore, does not have an “alternative future use”.
	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. The Company recorded the acquired BUPHENYL inventories at fair value in the amount of $3.9 million on the acquisition date. As of March 31, 2014, the entire fair value of acquired BUPHENYL inventory has been charged to expenses, primarily cost of sales.
	Intangible Assets
	Intangible assets are recorded at acquisition cost less accumulated amortization and impairment. Intangible assets with finite lives are amortized over their estimated useful lives. The Company’s intangible asset pertains to BUPHENYL product rights (see Note 7). Intangible assets are amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefits of the intangible asset are consumed as revenue is generated. The pattern of consumption of the economic benefits is estimated using the future projected cash flows of the intangible asset.
	Impairment of Long-lived Assets
	The Company reviews its property and equipment, intangible assets subject to amortization and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset class may not be recoverable. Recoverability is measured by comparing the carrying amount to the future net undiscounted cash flows that the assets are expected to generate. If such assets are considered impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value determined using projected discounted future net cash flows arising from the assets.
	Revenue Recognition
	The Company recognizes revenue in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, Revenue Recognition, when the following criteria have been met: persuasive evidence of an arrangement exists; delivery has occurred and risk of loss has passed; the seller’s price to the buyer is fixed or determinable and collectability is reasonably assured. The Company determines that persuasive evidence of an arrangement exists based on written contracts that defined the terms of the arrangements. In addition, the Company determines that services have been delivered in accordance with the arrangement. The Company assesses whether the fee is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. The Company assesses collectability based primarily on the customer’s payment history and on the creditworthiness of the customer.
	Product Revenue, net: The Company’s product revenue represents sales of RAVICTI and BUPHENYL which are recognized once all four revenue recognition criteria described above are met. The Company recognizes revenue net of product sales allowances. Product shipping and handling costs are included in cost of sales.
		•	During 2013, the Company began distributing RAVICTI to two specialty pharmacies through a specialty distributor. The specialty pharmacies then in turn dispensed RAVICTI to patients in fulfillment of prescriptions. As RAVICTI is a new product, and the Company’s first commercial product, the Company could not reasonably assess potential product sales allowances at the time of sale to the specialty distributor. As a result, the price of RAVICTI was not deemed fixed or determinable. The Company does not record revenue on shipments of RAVICTI to the specialty distributor, until the product is shipped to patients by the specialty pharmacies at which time the related product sales allowances can be reasonably estimated.
		•	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. The Company sells BUPHENYL in the United States to a specialty distributor who in turn sells this product to retail pharmacies, hospitals and other dispensing organizations. The Company records revenue on product shipments to the specialty distributor upon receipt by the specialty distributor. For product sales of BUPHENYL outside the United States, revenue is recognized once the product is accepted by the customer or their acceptance period has expired, whichever comes first.
	Product Sales Allowances: The Company establishes reserves for prompt-payment discounts, government and commercial rebates, product returns and chargebacks. Allowances relate to prompt-payment discounts and are recorded at the time of revenue recognition, resulting in a reduction in product sales revenue and a decrease in trade accounts receivables. Accruals related to government rebates, product returns and other applicable allowances such as distributor fees are recognized at the time of revenue recognition, resulting in a reduction in product sales and an increase in accrued expenses or a reduction in the related accounts receivable.
		•	Prompt-payment discounts: The specialty distributor and specialty pharmacies are offered prompt payment discounts. The Company expects the specialty distributor and specialty pharmacies will earn prompt payment discounts and, therefore deduct the full amount of these discounts from total product sales when revenues are recognized. The Company records prompt-payment discounts as allowances against accounts receivable on the condensed consolidated balance sheet.
		•	Rebates: Allowances for rebates include mandated discounts under the Medicaid Drug Rebate Program. Rebate amounts are based upon contractual agreements or legal requirements with public sector (e.g. Medicaid) benefit providers. Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and are based upon contractual agreements or legal requirements with public sector benefit providers. The allowance for rebates is based on statutory discount rates and expected utilization. The Company estimates for expected utilization of rebates based on historical data and data received from the specialty pharmacies. Rebates are generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarter’s unpaid rebates. If actual future rebates vary from estimates, the Company may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Allowance for rebates are recorded in accrued liabilities on the condensed consolidated balance sheet.
		•	Chargebacks: Chargebacks are discounts that occur when contracted customers purchase directly from a specialty distributor. Contracted customers, which primarily consist of Public Health Service institutions, non-profit clinics, and Federal government entities purchasing via the Federal Supply Schedule, generally purchase the product at a discounted price. The specialty distributor, in turn, charges back to the Company the difference between the price initially paid by the specialty distributor and the discounted price paid to the specialty distributor by the customer. For BUPHENYL, the allowance for chargebacks is based on historical sales data and known sales to contracted customers. For RAVICTI, the allowance for chargebacks is based on known sales to contracted customers. For qualified programs that can purchase the Company’s products through distributors at a lower contractual government price, the distributors charge back to the Company the difference between their acquisition cost and the lower contractual government price.
		•	Medicare Part D Coverage Gap: Medicare Part D prescription drug benefit mandates manufacturers to fund 50% of the Medicare Part D insurance coverage gap for prescription drugs sold to eligible patients. The Company estimates for the expected Medicare Part D coverage gap are based on historical invoices received and in part from data received from the specialty pharmacies. Funding of the coverage gap is generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters. If actual future funding varies from estimates, the Company may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Estimates of the Medicare Part D coverage gap are recorded in accrued liabilities on the condensed consolidated balance sheet.
		•	Distribution Service Fees: The Company has a written contract with the specialty distributor that includes terms for distribution-related fees. Distributor fees are calculated at percentage of gross sales based upon agreed contracted rate. The Company accrues distributor fees at the time of the revenue recognition, resulting in reduction of product sales revenue and the recording of accrued liabilities on the condensed consolidated balance sheets. The Company records distribution and other fees paid to its customers as a reduction of revenue, unless it receives an identifiable and separate benefit for the consideration and it can reasonably estimate the fair value of the benefit received. If both conditions are met, the Company records the consideration paid to the customer as an operating expense. These costs are typically known at the time of sale.
		•	Product Returns: Consistent with industry practice, the Company generally offers customers a limited right to return. The Company accepts returns of products from patients resulting from breakage as defined within the Company’s returns policy. Additionally, the Company considers several other factors in the estimation process including the expiration dates of product shipped, third party data in monitoring channel inventory levels, shelf life of the product, prescription trends and other relevant factors. Provisions for estimated product returns are recorded as accrued liabilities on the condensed consolidated balance sheet.
		•	Co-payment assistance: The Company provides a cash donation to a non-profit third party organization which supports patients, who have commercial insurance and meet certain financial eligibility requirements, with co-payment assistance and travel costs. The amount of co-payment assistance is accounted for by the Company as a reduction of revenues.
	Cost of sales
	Cost of sales includes third-party manufacturing cost of products sold, royalty fees, and other indirect costs related to personnel compensation, shipping and supplies. Costs incurred prior to FDA approval of RAVICTI have been recorded as research and development expense in the Company’s condensed consolidated statement of operations. The Company expects that cost of RAVICTI sales as a percentage of revenue will increase in future periods as product manufactured prior to FDA approval, and therefore fully expensed, is utilized.
	Cost of BUPHENYL sales as a percentage of revenue was higher and not indicative of cost of sales in future periods due to the recording of the step-up value on BUPHENYL inventories acquired from Ucyclyd which is expensed to cost of sales as that inventory is sold.
	Stock-Based Compensation
	The Company accounts for stock-based employee compensation arrangements in accordance with provisions of ASC 718, Compensation — Stock Compensation. ASC 718 requires the recognition of compensation expense, using a fair-value based method, for costs related to all share-based payments including stock options. ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The Company calculates the fair value of stock options using the Black-Scholes method and expenses using the straight-line attribution approach.
	Income Taxes
	The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference 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 affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.
	The Company accounts for uncertain tax positions in accordance with ASC 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.
	Foreign Currency Translations
	The Company has cash and accounts receivable denominated in foreign currency and is translated at the rate of exchange in effect on the balance sheet date. Revenue and expenses denominated in foreign currency are translated at the weighted average rate of exchange prevailing during the period. Any gains and losses resulting from foreign currency translations are included in other income (expense)-net in the condensed consolidated statements of operations.
	Comprehensive Income (Loss)
	Comprehensive income (loss) is comprised of net income (loss) and other comprehensive income. Other comprehensive income includes changes in stockholders’ equity that are excluded from net income (loss), specifically changes in unrealized gains and losses on the Company’s available-for-sale securities.
	Net Income (Loss) per Share of Common Stock
	Basic earnings per share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the periods presented. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and other potentially dilutive securities using the treasury stock method unless the effect is antidilutive.
	Recent Accounting Pronouncements
	In July 2013, FASB issued ASU No. 2013-11, Income Taxes (Topic 740): Presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. Under the amendments of this update an entity is required to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except as follows. To the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes that would result from the disallowance of a tax position or the tax law of the applicable jurisdiction does not require the entity to use, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The assessment of whether a deferred tax asset is available is based on the unrecognized tax benefit and deferred tax asset that exist at the reporting date and should be made presuming disallowance of the tax position at the reporting date. For example, an entity should not evaluate whether the deferred tax asset expires before the statute of limitations on the tax position or whether the deferred tax asset may be used prior to the unrecognized tax benefits being settled. The provisions of this update was effective prospectively for the Company in fiscal years beginning after December 15, 2013 with early adoption and retrospective application permitted. The Company adopted this guidance on January 1, 2014. The implementation did not have an impact on the Company’s condensed consolidated financial statements.

Collaboration_Agreement_with_U

Collaboration Agreement with Ucyclyd Pharma, Inc.	3 Months Ended
	Mar. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Collaboration Agreement with Ucyclyd Pharma, Inc.	'
	3. Collaboration Agreement with Ucyclyd Pharma, Inc.
	In March 2012, the Company entered into the purchase agreement with Ucyclyd under which the Company purchased the worldwide rights to RAVICTI and into an amended and restated collaboration agreement (the “restated collaboration agreement”) under which Ucyclyd granted the Company an option to purchase all of Ucyclyd’s worldwide rights to BUPHENYL and AMMONUL at a fixed price at a future defined date, plus subsequent milestone and royalty payments, subject to Ucyclyd’s right to retain AMMONUL for a predefined price. The restated collaboration agreement superseded the collaboration agreement with Ucyclyd, dated August 23, 2007, as amended. The entry into the purchase agreement and the restated collaboration agreement resolved a dispute that the two parties had with respect to their rights under the prior collaboration agreement.
	Under the purchase agreement, the Company made a payment of $6.0 million of which (i) $5.7 million was allocated to the worldwide rights to RAVICTI and (ii) $0.3 million was allocated to the option to purchase rights to BUPHENYL and AMMONUL, based on their relative fair values. The allocated amount to the rights to RAVICTI of $5.7 million was recorded to research and development expense in the consolidated statements of operations for the period ended March 31, 2012 due to the uncertainty of an alternative future use. The allocated amount for the option to purchase rights to BUPHENYL and AMMONUL in the amount of $0.3 million was included within other current assets and was subsequently offset against the gain recognized from the settlement of retention option.
	The Company will also pay tiered mid to high single digit royalties on global net sales of RAVICTI and may owe regulatory milestones of up to $15.8 million related to approval of GPB in HE, regulatory milestones of up to $7.3 million per indication for approval of GPB in indications other than UCD or HE, and net sales milestones of up to $38.8 million if GPB is approved for use in indications other than UCD (such as HE) and all annual sales targets are reached.
	In addition, the intellectual property license agreements executed between Ucyclyd and Dr. Marshall L. Summar, (“Summar”) and Ucyclyd and Brusilow Enterprises, LLC, (“Brusilow”) were assigned to the Company, and the Company has assumed the royalty and milestone obligations under the Brusilow agreement for sales of RAVICTI in any indication and the royalty obligations under the Summar agreement on sales of GPB to treat HE. The Brusilow and Summar agreements provide that royalty obligations will continue, without adjustment, even if generic versions of the licensed products are introduced and sold in the relevant country.
	Under the terms of the restated collaboration agreement, the Company had an option to purchase all of Ucyclyd’s worldwide rights in BUPHENYL and AMMONUL, subject to Ucyclyd’s option to retain rights to AMMONUL. The Company was permitted to exercise this option for 90 days beginning on the earlier of the date of the approval of RAVICTI for the treatment of UCD and June 30, 2013, but in no event earlier than January 1, 2013. The upfront purchase price for AMMONUL and BUPHENYL was $22.0 million. If the RAVICTI New Drug Application (“NDA”) for UCD was not approved by January 1, 2013, then Ucyclyd was obligated to make monthly payments of $0.5 million to the Company until the earliest of (1) FDA approval of the RAVICTI NDA for UCD, (2) June 30, 2013 and (3) the Company’s written notification of the decision not to purchase Ucyclyd’s worldwide rights to BUPHENYL and AMMONUL.
	On February 1, 2013, the FDA approved RAVICTI for the treatment of UCD in adult and pediatric patients two years of age and older. In accordance with the restated collaboration agreement, Ucyclyd made a payment of $0.5 million during the quarter ended March 31, 2013.
	On April 29, 2013, the Company exercised its option to purchase BUPHENYL and AMMONUL. Ucyclyd subsequently exercised its time-limited right to elect to retain all rights to AMMONUL for a contractual purchase price of $32.0 million (“retention amount”). Upon closing of the transaction, Ucyclyd paid the Company a net payment of $11.0 million, which reflects the Company’s contractual purchase price for Ucyclyd’s worldwide rights to BUPHENYL in the amount of $19.0 million being off-set against Ucyclyd’s retention amount for AMMONUL and a $2.0 million payment due to Ucyclyd for inventory that the Company purchased from Ucyclyd. The Company has retained a right of first negotiation should Ucyclyd later decide to sell, exclusively license, or otherwise transfer the AMMONUL assets to a third party.
	On May 31, 2013, the Company completed the acquisition of BUPHENYL.

Investments

Investments	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
Investments	'
	4. Investments
	All investments were classified as available-for-sale at March 31, 2014 and December 31, 2013, respectively. The principal amounts of investments by contractual maturity at March 31, 2014 and December 31, 2013 are summarized in the tables below:
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Period Ending March 31,					Value at		Gain (loss)			Fair Value at
		2015		2016			March 31, 2014					March 31, 2014
	Certificates of deposit	$	12,445	$	1,885		$	14,330	$	(13	)	$	14,317
	Corporate notes		16,921		1,984			18,905		2			18.907
	U.S. Government agency securities		8,007		—			8,007		—			8,007
	Commercial paper		3,494		—			3,494		1			3,495
	Total	$	40,867	$	3,869		$	44,736	$	(10	)	$	44,726
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Years Ending December 31,					Value at		Loss			Fair Value at
		2014		2015			December 31, 2013					December 31, 2013
	Certificates of deposit	$	10,525	$	2,845		$	13,370	$	(27	)	$	13,343
	Corporate notes		6,047		12,960			19,007		(24	)		18,983
	U.S. government agency securities		8,011		—			8,011		(3	)		8,008
	Commercial paper		3,492		—			3,492		(1	)		3,491
	Total	$	28,075	$	15,805		$	43,880	$	(55	)	$	43,825
	The Company evaluated its investments and determined that there were no other-than-temporary impairments as of March 31, 2014.
	The aggregate amounts of unrealized losses and related fair value of investments with unrealized losses as of March 31, 2014 and December 31, 2013 were as follows:
		Less Than 12 Months to					12 Months or More to					Total at March 31, 2014
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Gain (loss)			Fair Value		Loss			Fair Value		Gain (loss)
	Certificates of deposit	$	12,435	$	(10	)	$	1,882	$	(3	)	$	14,317	$	(13	)
	Corporate notes		16,924		3			1,983		(1	)		18,907		2
	U.S. government agency securities		8,007		—			—		—			8,007		—
	Commercial paper		3,495		1			—		—			3,495		1
	Total	$	40,861	$	(6	)	$	3,865	$	(4	)	$	44,726	$	(10	)
		Less Than 12 Months to					12 Months or More to					Total at December 31, 2013
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Loss			Fair Value		Loss			Fair Value		Loss
	Certificates of deposit	$	10,507	$	(18	)	$	2,836	$	(9	)	$	13,343	$	(27	)
	Corporate notes		6,039		(8	)		12,944		(16	)		18,983		(24	)
	U.S. government agency securities		8,008		(3	)		—		—			8,008		(3	)
	Commercial paper		3,491		(1	)		—		—			3,491		(1	)
	Total	$	28,045	$	(30	)	$	15,780	$	(25	)	$	43,825	$	(55	)

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	5. Fair Value Measurements
	The Company follows ASC 820-10, “Fair Value Measurements and Disclosures,” which among other things, defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows:
		•		Level 1 — Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
		•		Level 2 — Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life.
		•		Level 3 — Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
	The following table presents the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of March 31, 2014 and December 31, 2013 (in thousands):
			Fair Value Measurements at March 31, 2014
			Quoted Price in		Significant Other		Significant		Total
			Active Markets		Observable Inputs		Unobservable
			for Identical Assets		(Level 2)		Inputs
			(Level 1)				(Level 3)
	Assets:
	Cash equivalents:
	Money market funds		$	38,211	$	—	$	—	$	38,211
	Total cash equivalents		$	38,211	$	—	$	—	$	38,211
	Available-for-sale securities:
	Short-term:
	Certificates of deposit		$	—	$	12,435	$	—	$	12,435
	Commercial paper			—		3,495		—		3,495
	Corporate notes			—		16,924		—		16,924
	U.S. Government agency securities			—		8,007		—		8,007
	Total short-term investments			—		40,861		—		40,861
	Long-term:
	Certificates of deposit			—		1,882		—		1,882
	Corporate notes			—		1,983		—		1,983
	Total long-term investments			—		3,865		—		3,865
	Total available-for-sale securities		$	—	$	44,726	$	—	$	44,726
			Fair Value Measurements at December 31, 2013
			Quoted Price in		Significant Other		Significant		Total
			Active Markets		Observable Inputs		Unobservable
			for Identical Assets		(Level 2)		Inputs
			(Level 1)				(Level 3)
	Assets:
	Cash equivalents:
	Money market funds		$	38,506	$	—	$	—	$	38,506
	Certificates of deposit			—		480		—		480
	Total cash equivalents		$	38,506	$	480	$	—	$	38,986
	Available-for-sale securities:
	Short-term:
	Certificates of deposit		$	—	$	10,507	$	—	$	10,507
	Commercial paper			—		3,491		—		3,491
	Corporate notes			—		6,039		—		6,039
	U.S. Government agency securities			—		8,008		—		8,008
	Total short-term investments			—		28,045		—		28,045
	Long-term:
	Certificates of deposit			—		2,836		—		2,836
	Corporate notes			—		12,944		—		12,944
	Total long-term investments			—		15,780		—		15,780
	Total available-for-sale securities		$	—	$	43,825	$	—	$	43,825
	The following table presents the carrying value and estimated fair value of the Company’s notes payable as of March 31, 2014 and December 31, 2013 (in thousands):
			March 31, 2014
			Carrying		Estimated
			Value		Fair Value
	April and September 2012 Notes		$	7,037	$	7,517
			December 31, 2013
			Carrying		Estimated
			Value		Fair Value
	April and September 2012 Notes		$	8,273	$	8,860
	Valuation Techniques
	The Company classifies money market funds, which are valued based on quoted market prices in active markets with no valuation adjustment, as Level 1 assets within the fair value hierarchy.
	Items classified as Level 2 within the valuation hierarchy consist of commercial paper, corporate notes, U.S. government agency securities and certificates of deposit. The Company estimates the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. The Company validates the prices provided by our third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.
	The Company has determined that its notes payable would be classified as a Level 3 item in the fair value hierarchy. The fair value of these notes is based on the present value of expected future cash flows and assumptions about current interest rates and the credit worthiness of the Company.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	6. Inventories
	The following table represents the components of inventories (in thousands):
		March 31,		December 31,
		2014		2013
	Raw Materials	$	149	$	697
	Work-in-process		317		—
	Finished goods		2,359		2,816
	Total	$	2,825	$	3,513
	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. As part of the acquisition, the Company purchased inventories from Ucyclyd and the Company recorded these inventories at fair value in the amount of $3.9 million on the Acquisition Date. As of March 31, 2014, the entire fair value of acquired BUPHENYL inventory has been charged to expenses, primarily cost of sales.

Intangible_Asset

Intangible Asset	3 Months Ended
	Mar. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]	'
Intangible Asset	'
	7. Intangible Asset
	The Company acquired BUPHENYL and as part of this transaction, the Company recognized $16.5 million of an intangible asset relating to BUPHENYL product rights. The estimated fair value attributed to the BUPHENYL product rights was determined on a discounted forecast of the estimated net future cash flows to be generated from the product rights. Intangible assets are amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefits of the intangible assets are consumed as revenue is generated. The pattern of consumption of the economic benefits is estimated using the future projected cash flows of the intangible asset. The Company estimated the useful life of the BUPHENYL product rights to be 10 years.
	Intangible asset amortization expense was $1.0 million for the three months ended March 31, 2014.
	Estimated aggregate amortization expense for each of the five succeeding years ending December 31 is as follows (in thousands):
		2014		2015		2016		2017		2018
	Amortization expense	$	4,053	$	3,294	$	1,157	$	1,048	$	1,012

Property_and_Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2014
Property Plant And Equipment [Abstract]	'
Property and Equipment	'
	8. Property and Equipment
	The following table represents the components of property and equipment (in thousands):
		March 31,			December 31,
		2014			2013
	Computers and Software	$	839		$	563
	Furniture and Fixtures		320			320
	Office Equipment		53			53
	Capital work in progress		17			264
			1,229			1,200
	Less: Accumulated depreciation		(367	)		(264	)
	Total property and equipment, net	$	862		$	936
	Depreciation expense for the period ended March 31, 2014 and 2013 was $0.1 million and $19,000, respectively.

Accrued_Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 31, 2014
Payables And Accruals [Abstract]	'
Accrued Liabilities	'
	9. Accrued Liabilities
	The following table represents the components of accrued liabilities (in thousands):
		March 31,		December 31,
		2014		2013
	Pre-clinical and clinical trial expenses	$	244	$	246
	Payroll and related expenses		1,691		4,278
	Gross to net sales accruals		5,850		5,235
	Royalty payable		1,247		1,154
	Legal accrual		598		45
	Taxes payable		245		326
	Interest payable		52		61
	Other		1,068		842
	Total	$	10,995	$	12,187

Notes_Payable

Notes Payable	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Notes Payable	'
	10. Notes Payable
	In April 2012, the Company borrowed $10.0 million (the “April 2012 Notes”) pursuant to a loan and security agreement (the “Loan Agreement”) with Silicon Valley Bank and Leader Lending, LLC—Series B (the “Lenders”). The loan carries an interest rate of 8.88%, with interest only payments for the period of 9 months from May 1, 2012. The loan is then payable in equal monthly principal payments plus interest over a period of 27 months from February 1, 2013. In connection with the Loan Agreement, the Company granted a security interest in all of its assets, except intellectual property. The Company’s obligations to the Lenders include restrictions on borrowing, asset transfers, placing liens or security interest on its assets including the Company’s intellectual property, mergers and acquisitions and distributions to stockholders. The Loan Agreement also requires the Company to provide the Lenders monthly financials and compliance certificate within 30 days of each month end, annual audited financials within 180 days of each fiscal year-end and annual approved financial projections. The Company issued warrants to the Lenders to purchase a total of 75,974 shares of common stock with an exercise price of $4.08 per share. The Loan Agreement requires immediate repayment of amounts outstanding upon an event of default, as defined in the Loan Agreement, which includes events such as a payment default, a covenant default or the occurrence of a material adverse change, as defined in the Loan Agreement. In addition, a final payment equal to 6.5% of the principal loan amount is due on the earlier of (i) maturity date, (ii) prepayment of the loan or (iii) an event of default.
	Pursuant to the terms of the Loan Agreement, once the Company raised at least $30.0 million from the sale of equity securities or subordinated debt, the Lenders agreed to lend the Company a one-time single loan in the amount of $2.5 million (the “Bank Term Loan”). In September 2012, the Company borrowed an additional $2.5 million (the “September 2012 Note”) from Silicon Valley Bank pursuant to the terms of the Bank Term Loan. In addition, the Company issued warrants to Silicon Valley Bank to purchase a total of 8,408 shares of common stock with an exercise price of $5.05 per share. A final payment equal to 6.5% of the principal loan amount is due on the earlier of (i) maturity date, (ii) prepayment of the loan or (iii) an event of default. The principal amount outstanding under the Bank Term Loan accrues interest at a per annum rate equal to the greater of (i) 8.88% and (ii) the Treasury Rate, as defined in the Loan Agreement, on the date the loan is funded plus 8.50%, with interest only payments for the period of 9 months from the date the loan is funded. The loan is then payable in equal monthly principal payments plus interest over a period of 27 months from the date the loan is funded.
	For the three months ended March 31, 2014 and March 31, 2013, the Company recorded amortization of debt discount of $0.1 million related to the April 2012 Notes and September 2012 Note.

Warrants

Warrants	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Warrants	'
	11. Warrants
	In connection with a Loan and Security Agreement entered into in October 2007, the Company issued warrants to purchase 274 shares of Series B convertible preferred stock. In June 2009, as part of the recapitalization, these warrants were converted into warrants to purchase shares of common stock. The warrants are exercisable at $1,913.05 per share and will expire in October 2017 (the “October 2007 common stock warrants”).
	The following table summarizes the outstanding warrants and the corresponding exercise price as of March 31, 2014 and December 31, 2013:
		Number of Shares Outstanding
		March 31,		December 31,		Per Share
		2014		2013		Exercise Price
	October 2007 common stock warrants		274		274	$	1,913.05
	Total		274		274

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	12. Commitments and Contingencies
	Contingencies
	In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future, but have not yet been made. Further, the Company may be subject to certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated.
	In accordance with the Company’s amended and restated certificate of incorporation and amended and restated bylaws, the Company has indemnification obligations to its officers and directors for certain events or occurrences, subject to certain limits, while they are serving at the Company’s request in such capacity. There have been no claims to date and the Company has a director and officer insurance policy that may enable it to recover a portion of any amounts paid for future claims.
	The Company is contingently committed for development milestone payments as well as sales-related milestone payments and royalties relating to potential future product sales under the restated collaboration agreement and purchase agreement with Ucyclyd (Note 3). The amount, timing and likelihood of these payments are unknown as they are dependent on the occurrence of future events that may or may not occur, including approval by the FDA of GPB for HE.
	Other Matters
	From time to time, the Company is a party to or otherwise involved in legal proceedings, claims and government inspections and other legal matters arising in the ordinary course of business or otherwise. See Note 17, “Subsequent Events” of the Notes to the Condensed Consolidated Financial Statements, which discussion is incorporated herein by reference.

Equity_Incentive_Plan_and_Stoc

Equity Incentive Plan and Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Equity Incentive Plan and Stock-Based Compensation	'
	13. Equity Incentive Plan and Stock-Based Compensation
	Equity Incentive Plans
	In April 2012, the board of directors of the Company adopted the 2012 Omnibus Incentive Plan (the “2012 Plan”). The Company’s stockholders approved the 2012 Plan in July 2012. The 2012 Plan provides for the grant of stock options, stock appreciation rights, restricted stock, unrestricted stock, stock units, dividend equivalent rights, other equity-based awards and cash bonus awards. The 2012 Plan became effective on July 25, 2012.
	Effective January 1, 2014, pursuant to the provisions of the 2012 Plan providing for an annual automatic increase in the number of shares of common stock reserved for issuance under the plan, the shares available for issuance under the 2012 Plan increased by 805,485 shares. As of March 31, 2014, the Company had 880,495 shares of common stock available for issuance and 1,610,436 options and 114,753 restricted stock units (“RSU’s”) were outstanding under the 2012 Plan. During the three months ended March 31, 2014, the board of directors approved the grants of 512,105 stock options at exercise prices in the range of $25.80 - $31.00 and 101,253 RSU’s (including 1,500 performance RSU’s to certain employees) under the 2012 Plan.
	On July 25, 2012, the effective date of the 2012 Plan, the 2006 Equity Incentive Plan was frozen and no additional awards will be made under the 2006 Plan. Any shares remaining available for future grant were allocated to the 2012 Plan and any shares underlying outstanding options that terminate by expiration, forfeiture, cancellation, or otherwise without issuance of such shares, will be allocated to the 2012 Plan. As of March 31, 2014, there were 1,463,325 options outstanding under the 2006 Plan.
	In March 2014, the Company recorded an expense of $0.1 million related to the modification of certain stock options.
	Stock-Based Compensation
	The Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options and RSU’s is being amortized on a straight-line basis over the requisite service period of the awards.
	Total stock-based compensation expense related to options granted was allocated as follows (in thousands):
		Three Months Ended
		March 31,
		2014		2013
	Cost of sales	$	2	$	1
	Research and development		147		91
	Selling general and administrative		1,219		413
	Total	$	1,368	$	505
	Stock-based compensation of $8,000 and $9,000 was capitalized into inventories for the three months ended March 31, 2014 and 2013, respectively. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold. Allocations to research and development, selling, general and administrative expenses are based upon the department to which the associated employee reported.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	14. Income Taxes
	At December 31, 2013, the Company had net operating loss carryforwards of approximately $72.5 million and $112.5 million available to reduce future taxable income, if any, for both federal and California state income tax purposes, respectively. The net operating loss carryforwards will begin to expire in 2026 for federal and 2016 for state purposes.
	The Company was granted orphan drug designation in 2009 by the FDA for its products currently under development. The orphan drug designation allows the Company to claim increased federal tax credits for its research and development activities. The Company had $18.0 million of federal credit carryforwards of which $17.4 million relates to Orphan Drug Credit claims for 2009 through 2013.
	For the period ended March 31, 2014, the Company recorded an income tax expense of $0.1 million. Expected taxable income in 2014 will largely be offset by federal and state net operating losses and credits.
	There was no interest or penalties accrued through March 31, 2014. The Company’s policy is to recognize any related interest or penalties in income tax expense. The material jurisdiction in which the Company is subject to potential examination by tax authorities for tax years ended 2006 through the current period include the United States and California. The Company is not currently under income tax examinations by any tax authorities.

Net_Income_Loss_per_Share_of_C

Net Income (Loss) per Share of Common Stock	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Net Income (Loss) per Share of Common Stock	'
	15. Net Income (Loss) per Share of Common Stock
	The following table sets forth the computation of basic and diluted net income (loss) per share of common stock for the periods indicated (in thousands, except share and per share amounts):
		Three Months Ended
		March 31,
		2014		2013
	Net income (loss) per share
	Numerator:
	Net income (loss) attributable to common stockholders	$	1,259	$	(8,975	)
	Denominator:
	Weighted-average number of common shares outstanding – basic		20,191,190		17,366,848
	Dilutive effect of stock-options and awards		1,327,336		—
	Weighted average common shares outstanding – dilutive		21,518,526		17,366,848
	Net income (loss) per share:
	Basic	$	0.06	$	(0.52	)
	Diluted	$	0.06	$	(0.52	)
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income (loss) per share, as the effect of including them would have been antidilutive:
		Three Months Ended
		March 31,
		2014		2013
	Stock options		1,181,650		2,112,455
	October 2007, April 2008 and 2012 common stock warrants		274		38,261
	Total		1,181,924		2,150,716

Related_Party_Transaction

Related Party Transaction	3 Months Ended
	Mar. 31, 2014
Related Party Transactions [Abstract]	'
Related Party Transaction	'
	16. Related Party Transaction
	As part of the Company’s acquisition of BUPHENYL, the Company assumed the existing BUPHENYL distributor’s agreements, including the distribution agreement with Swedish Orphan Biovitrum AB (“SOBI”). Additionally, in the third quarter of 2013 SOBI was granted exclusive rights by the Company to distribute RAVICTI on a named patient basis for the chronic treatment of UCD in various territories in the Middle East. SOBI’s chairman, Bo Jesper Hansen, is a member of the Company’s Board of Directors. During the three months ended March 31, 2014 the Company recognized $0.3 million from sales to SOBI. As of March 31, 2014, trade receivable from SOBI amounted to $0.3 million.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	17. Subsequent Events
	On April 23, 2014, the Company and Hyperion Therapeutics Israel Holding Corp. Ltd., a wholly owned subsidiary of the Company, entered into a Share Purchase Agreement (the “Purchase Agreement”) with Andromeda Biotech Ltd, an Israeli company (“Andromeda”), and Clal Biotechnology Industries Ltd. (“Clal”). Andromeda is focused on the development of DiaPep277 ® , a first-in-class immune intervention therapy for new onset Type 1 diabetes. DiaPep277 is currently being evaluated in a confirmatory Phase 3 clinical study in adult patients with new onset Type 1 diabetes. Pursuant to the terms and conditions set forth in the Purchase Agreement, the Company through its wholly owned subsidiary will purchase all of the outstanding ordinary shares of Andromeda from Clal (the “Purchase”), with the result being that Andromeda will become a wholly owned subsidiary of the Company after the Purchase. The Company will fund the acquisition from its existing cash and cash equivalent and investment balances. Upon closing of the Purchase, the Company will pay Andromeda’s securityholders, including a former holder of Andromeda’s ordinary shares and holders of options to purchase shares of Andromeda’s ordinary shares, an aggregate of $12.5 million in cash, less adjustments for expenses incurred in connection with the transaction, and will issue 312,869 shares of its common stock. The common stock will be valued at approximately $7.85 million and is based on the average closing price of $25.09 per share for the 15 consecutive trading days ending April 17, 2014. As additional consideration, the Company will pay the former securityholders of Andromeda contingent payments as follows: (i) potential global regulatory and approval milestones payments that total $120 million, the first of which would be due upon acceptance of the first marketing application filing for review in either the US or Europe, whichever occurs first; (ii) up to $430 million in commercial milestones, the first of which would be due upon achievement of annual worldwide net sales of $450 million, and (iii) tiered contingent sales payments ranging from 10% on annual worldwide net sales up to $300 million to 17% for annual worldwide net sales that exceed $1.2 billion, with the exception of sales by distributors in certain territories, for which the rate is 25%. The closing of the Purchase is subject to various closing conditions, including that Clal is the sole holder of Andromeda’s outstanding ordinary shares and other customary closing conditions. The Purchase Agreement may be terminated by either party upon the occurrence of certain events, including if the Purchase did not close by June 15, 2014. The Purchase is currently expected to close in the second quarter of 2014.
	On March 17, 2014, the Company received notification from the generic drug manufacturer Par Pharmaceutical, Inc. (“Par”) that it had filed an Abbreviated New Drug Application containing a Paragraph IV certification with the FDA seeking approval for a generic version of RAVICTI Oral Liquid. The Paragraph IV certification alleges that certain of the Company’s patents are invalid and/or will not be infringed by Par’s manufacture, use or sale of the product for which the ANDA was submitted. The Company filed suit against Par on April 23, 2014 to protect its patents.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The accompanying interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and on a basis consistent with the annual consolidated financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the periods presented. These interim financial results are not necessarily indicative of the results to be expected for the year ending December 31, 2014, or for any other future annual or interim period. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
Use of Estimates	'
	Use of Estimates
	The preparation of the interim condensed consolidated financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to fair value of assets and liabilities, intangible asset valuation, stock-based compensation expense, income taxes, revenue recognition and product sales allowances. Management bases its estimates on historical experience or on various other assumptions, including information received from its service providers, which it believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Segment Reporting	'
	Segment Reporting
	The Company operates as one operating segment and uses one measurement of profitability to manage its business. All long-lived assets are maintained in the United States. For the three months ended March 31, 2014, net product revenue in the United States and rest of the world (primarily Canada and Europe) was $18.0 million and $1.5 million, respectively. For the three months ended March 31, 2014, net product revenue consisted of net sales from RAVICTI of $15.5 million and net sales from BUPHENYL of $4.0 million. For the three months ended March 31, 2013, net product revenue for RAVICTI in the United States was $0.8 million.
Concentration of Credit Risk and Significant customers	'
	Concentration of Credit Risk and Significant customers
	The Company’s cash and cash equivalents and investments are maintained with financial institutions located in the United States. Deposits in these institutions may exceed the amount of insurance provided on such deposits. The Company has not recognized any losses from credit risks during the periods presented and management does not believe that the Company is exposed to significant credit risk from its cash and cash equivalents or investments.
	The Company is also subject to credit risk from its accounts receivables related to its product sales. The Company monitors its exposure within accounts receivable and records a reserve against uncollectible accounts receivable as necessary. The Company extends credit to a specialty distributor in the United States and to international distributors, pharmacies and hospitals outside the United States. Customer creditworthiness is monitored and collateral is not required. As of March 31, 2014, there were no credit losses on the Company’s accounts receivable. As of March 31, 2014, the specialty distributor in the United States accounted for 64% of the accounts receivable balance and one international distributor accounted for 12% of the accounts receivable balance.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	The Company measures certain financial assets and liabilities at fair value based on the exchange price that would be received for an asset or paid for to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. The carrying amounts of the Company’s financial instruments, including cash equivalents, short-term investments, the option to purchase BUPHENYL and AMMONUL (Note 3), accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of long-term investments represent their estimated fair values. The Company’s debt obligations are carried at historical cost, which approximates fair value.
Business Combinations	'
	Business Combinations
	The Company allocates the purchase price of an acquired business to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. Any excess of the purchase price over the fair value of the net assets acquired is recorded as goodwill. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets. Direct transaction costs associated with the business combination are expensed as incurred.
Accounts Receivable	'
	Accounts Receivable
	Trade accounts receivable are recorded net of product sales allowances for prompt-payment discounts, chargebacks, and doubtful accounts. Estimates for chargebacks and prompt-payment discounts are based on contractual terms, historical trends and expectations regarding the utilization rates for these programs. At March 31, 2014, the Company had no allowances for doubtful accounts.
Inventories	'
	Inventories
	Inventories are stated at the lower of cost or market value with cost determined under the first-in-first-out (FIFO) cost method and consists of raw materials, work-in-progress and finished goods. Costs to be capitalized as inventories include third party manufacturing costs, associated compensation related costs of personnel indirectly involved in the manufacturing process and other overhead costs such as ancillary supplies. Subsequent to FDA approval of RAVICTI on February 1, 2013, the Company began capitalizing RAVICTI inventories as the related costs were expected to be recoverable through the commercialization of the product. Costs incurred prior to the FDA approval of RAVICTI have been recorded as research and development expense in the condensed consolidated statements of operations. If information becomes available that suggest that inventories may not be realizable, the Company may be required to expense a portion or all of the previously capitalized inventories.
	Products that have been approved by the FDA or other regulatory authorities, such as RAVICTI, are also used in clinical programs, to assess the safety and efficacy of the products for usage in diseases that have not been approved by the FDA or other regulatory authorities. The form of RAVICTI utilized for both commercial and clinical programs is identical and, as a result, the inventory has an “alternative future use” as defined in authoritative guidance. Raw materials and purchased drug product associated with clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes and, therefore, does not have an “alternative future use”.
	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. The Company recorded the acquired BUPHENYL inventories at fair value in the amount of $3.9 million on the acquisition date. As of March 31, 2014, the entire fair value of acquired BUPHENYL inventory has been charged to expenses, primarily cost of sales.
Intangible Assets	'
	Intangible Assets
	Intangible assets are recorded at acquisition cost less accumulated amortization and impairment. Intangible assets with finite lives are amortized over their estimated useful lives. The Company’s intangible asset pertains to BUPHENYL product rights (see Note 7). Intangible assets are amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefits of the intangible asset are consumed as revenue is generated. The pattern of consumption of the economic benefits is estimated using the future projected cash flows of the intangible asset.
Impairment of Long-lived Assets	'
	Impairment of Long-lived Assets
	The Company reviews its property and equipment, intangible assets subject to amortization and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset class may not be recoverable. Recoverability is measured by comparing the carrying amount to the future net undiscounted cash flows that the assets are expected to generate. If such assets are considered impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value determined using projected discounted future net cash flows arising from the assets.
Revenue Recognition	'
	Revenue Recognition
	The Company recognizes revenue in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, Revenue Recognition, when the following criteria have been met: persuasive evidence of an arrangement exists; delivery has occurred and risk of loss has passed; the seller’s price to the buyer is fixed or determinable and collectability is reasonably assured. The Company determines that persuasive evidence of an arrangement exists based on written contracts that defined the terms of the arrangements. In addition, the Company determines that services have been delivered in accordance with the arrangement. The Company assesses whether the fee is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. The Company assesses collectability based primarily on the customer’s payment history and on the creditworthiness of the customer.
	Product Revenue, net: The Company’s product revenue represents sales of RAVICTI and BUPHENYL which are recognized once all four revenue recognition criteria described above are met. The Company recognizes revenue net of product sales allowances. Product shipping and handling costs are included in cost of sales.
		•	During 2013, the Company began distributing RAVICTI to two specialty pharmacies through a specialty distributor. The specialty pharmacies then in turn dispensed RAVICTI to patients in fulfillment of prescriptions. As RAVICTI is a new product, and the Company’s first commercial product, the Company could not reasonably assess potential product sales allowances at the time of sale to the specialty distributor. As a result, the price of RAVICTI was not deemed fixed or determinable. The Company does not record revenue on shipments of RAVICTI to the specialty distributor, until the product is shipped to patients by the specialty pharmacies at which time the related product sales allowances can be reasonably estimated.
		•	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. The Company sells BUPHENYL in the United States to a specialty distributor who in turn sells this product to retail pharmacies, hospitals and other dispensing organizations. The Company records revenue on product shipments to the specialty distributor upon receipt by the specialty distributor. For product sales of BUPHENYL outside the United States, revenue is recognized once the product is accepted by the customer or their acceptance period has expired, whichever comes first.
	Product Sales Allowances: The Company establishes reserves for prompt-payment discounts, government and commercial rebates, product returns and chargebacks. Allowances relate to prompt-payment discounts and are recorded at the time of revenue recognition, resulting in a reduction in product sales revenue and a decrease in trade accounts receivables. Accruals related to government rebates, product returns and other applicable allowances such as distributor fees are recognized at the time of revenue recognition, resulting in a reduction in product sales and an increase in accrued expenses or a reduction in the related accounts receivable.
		•	Prompt-payment discounts: The specialty distributor and specialty pharmacies are offered prompt payment discounts. The Company expects the specialty distributor and specialty pharmacies will earn prompt payment discounts and, therefore deduct the full amount of these discounts from total product sales when revenues are recognized. The Company records prompt-payment discounts as allowances against accounts receivable on the condensed consolidated balance sheet.
		•	Rebates: Allowances for rebates include mandated discounts under the Medicaid Drug Rebate Program. Rebate amounts are based upon contractual agreements or legal requirements with public sector (e.g. Medicaid) benefit providers. Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and are based upon contractual agreements or legal requirements with public sector benefit providers. The allowance for rebates is based on statutory discount rates and expected utilization. The Company estimates for expected utilization of rebates based on historical data and data received from the specialty pharmacies. Rebates are generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarter’s unpaid rebates. If actual future rebates vary from estimates, the Company may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Allowance for rebates are recorded in accrued liabilities on the condensed consolidated balance sheet.
		•	Chargebacks: Chargebacks are discounts that occur when contracted customers purchase directly from a specialty distributor. Contracted customers, which primarily consist of Public Health Service institutions, non-profit clinics, and Federal government entities purchasing via the Federal Supply Schedule, generally purchase the product at a discounted price. The specialty distributor, in turn, charges back to the Company the difference between the price initially paid by the specialty distributor and the discounted price paid to the specialty distributor by the customer. For BUPHENYL, the allowance for chargebacks is based on historical sales data and known sales to contracted customers. For RAVICTI, the allowance for chargebacks is based on known sales to contracted customers. For qualified programs that can purchase the Company’s products through distributors at a lower contractual government price, the distributors charge back to the Company the difference between their acquisition cost and the lower contractual government price.
		•	Medicare Part D Coverage Gap: Medicare Part D prescription drug benefit mandates manufacturers to fund 50% of the Medicare Part D insurance coverage gap for prescription drugs sold to eligible patients. The Company estimates for the expected Medicare Part D coverage gap are based on historical invoices received and in part from data received from the specialty pharmacies. Funding of the coverage gap is generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters. If actual future funding varies from estimates, the Company may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Estimates of the Medicare Part D coverage gap are recorded in accrued liabilities on the condensed consolidated balance sheet.
		•	Distribution Service Fees: The Company has a written contract with the specialty distributor that includes terms for distribution-related fees. Distributor fees are calculated at percentage of gross sales based upon agreed contracted rate. The Company accrues distributor fees at the time of the revenue recognition, resulting in reduction of product sales revenue and the recording of accrued liabilities on the condensed consolidated balance sheets. The Company records distribution and other fees paid to its customers as a reduction of revenue, unless it receives an identifiable and separate benefit for the consideration and it can reasonably estimate the fair value of the benefit received. If both conditions are met, the Company records the consideration paid to the customer as an operating expense. These costs are typically known at the time of sale.
		•	Product Returns: Consistent with industry practice, the Company generally offers customers a limited right to return. The Company accepts returns of products from patients resulting from breakage as defined within the Company’s returns policy. Additionally, the Company considers several other factors in the estimation process including the expiration dates of product shipped, third party data in monitoring channel inventory levels, shelf life of the product, prescription trends and other relevant factors. Provisions for estimated product returns are recorded as accrued liabilities on the condensed consolidated balance sheet.
		•	Co-payment assistance: The Company provides a cash donation to a non-profit third party organization which supports patients, who have commercial insurance and meet certain financial eligibility requirements, with co-payment assistance and travel costs. The amount of co-payment assistance is accounted for by the Company as a reduction of revenues.
Cost of sales	'
	Cost of sales
	Cost of sales includes third-party manufacturing cost of products sold, royalty fees, and other indirect costs related to personnel compensation, shipping and supplies. Costs incurred prior to FDA approval of RAVICTI have been recorded as research and development expense in the Company’s condensed consolidated statement of operations. The Company expects that cost of RAVICTI sales as a percentage of revenue will increase in future periods as product manufactured prior to FDA approval, and therefore fully expensed, is utilized.
	Cost of BUPHENYL sales as a percentage of revenue was higher and not indicative of cost of sales in future periods due to the recording of the step-up value on BUPHENYL inventories acquired from Ucyclyd which is expensed to cost of sales as that inventory is sold.
Stock-Based Compensation	'
	Stock-Based Compensation
	The Company accounts for stock-based employee compensation arrangements in accordance with provisions of ASC 718, Compensation — Stock Compensation. ASC 718 requires the recognition of compensation expense, using a fair-value based method, for costs related to all share-based payments including stock options. ASC 718 requires companies to estimate the fair value of share-based payment awards on the date of grant using an option-pricing model. The Company calculates the fair value of stock options using the Black-Scholes method and expenses using the straight-line attribution approach.
Income Taxes	'
	Income Taxes
	The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference 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 affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.
	The Company accounts for uncertain tax positions in accordance with ASC 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.
Foreign Currency Translations	'
	Foreign Currency Translations
	The Company has cash and accounts receivable denominated in foreign currency and is translated at the rate of exchange in effect on the balance sheet date. Revenue and expenses denominated in foreign currency are translated at the weighted average rate of exchange prevailing during the period. Any gains and losses resulting from foreign currency translations are included in other income (expense)-net in the condensed consolidated statements of operations.
Comprehensive Income (loss)	'
	Comprehensive Income (Loss)
	Comprehensive income (loss) is comprised of net income (loss) and other comprehensive income. Other comprehensive income includes changes in stockholders’ equity that are excluded from net income (loss), specifically changes in unrealized gains and losses on the Company’s available-for-sale securities.
Net Income (Loss) per Share of Common Stock	'
	Net Income (Loss) per Share of Common Stock
	Basic earnings per share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the periods presented. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and other potentially dilutive securities using the treasury stock method unless the effect is antidilutive.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In July 2013, FASB issued ASU No. 2013-11, Income Taxes (Topic 740): Presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. Under the amendments of this update an entity is required to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except as follows. To the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes that would result from the disallowance of a tax position or the tax law of the applicable jurisdiction does not require the entity to use, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The assessment of whether a deferred tax asset is available is based on the unrecognized tax benefit and deferred tax asset that exist at the reporting date and should be made presuming disallowance of the tax position at the reporting date. For example, an entity should not evaluate whether the deferred tax asset expires before the statute of limitations on the tax position or whether the deferred tax asset may be used prior to the unrecognized tax benefits being settled. The provisions of this update was effective prospectively for the Company in fiscal years beginning after December 15, 2013 with early adoption and retrospective application permitted. The Company adopted this guidance on January 1, 2014. The implementation did not have an impact on the Company’s condensed consolidated financial statements.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
Schedule of Investments by Contractual Maturity	'
	The principal amounts of investments by contractual maturity at March 31, 2014 and December 31, 2013 are summarized in the tables below:
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Period Ending March 31,					Value at		Gain (loss)			Fair Value at
		2015		2016			March 31, 2014					March 31, 2014
	Certificates of deposit	$	12,445	$	1,885		$	14,330	$	(13	)	$	14,317
	Corporate notes		16,921		1,984			18,905		2			18.907
	U.S. Government agency securities		8,007		—			8,007		—			8,007
	Commercial paper		3,494		—			3,494		1			3,495
	Total	$	40,867	$	3,869		$	44,736	$	(10	)	$	44,726
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Years Ending December 31,					Value at		Loss			Fair Value at
		2014		2015			December 31, 2013					December 31, 2013
	Certificates of deposit	$	10,525	$	2,845		$	13,370	$	(27	)	$	13,343
	Corporate notes		6,047		12,960			19,007		(24	)		18,983
	U.S. government agency securities		8,011		—			8,011		(3	)		8,008
	Commercial paper		3,492		—			3,492		(1	)		3,491
	Total	$	28,075	$	15,805		$	43,880	$	(55	)	$	43,825
Schedule of Unrealized Losses and Related Fair Value of Investments with Unrealized Losses	'
	The aggregate amounts of unrealized losses and related fair value of investments with unrealized losses as of March 31, 2014 and December 31, 2013 were as follows:
		Less Than 12 Months to					12 Months or More to					Total at March 31, 2014
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Gain (loss)			Fair Value		Loss			Fair Value		Gain (loss)
	Certificates of deposit	$	12,435	$	(10	)	$	1,882	$	(3	)	$	14,317	$	(13	)
	Corporate notes		16,924		3			1,983		(1	)		18,907		2
	U.S. government agency securities		8,007		—			—		—			8,007		—
	Commercial paper		3,495		1			—		—			3,495		1
	Total	$	40,861	$	(6	)	$	3,865	$	(4	)	$	44,726	$	(10	)
		Less Than 12 Months to					12 Months or More to					Total at December 31, 2013
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Loss			Fair Value		Loss			Fair Value		Loss
	Certificates of deposit	$	10,507	$	(18	)	$	2,836	$	(9	)	$	13,343	$	(27	)
	Corporate notes		6,039		(8	)		12,944		(16	)		18,983		(24	)
	U.S. government agency securities		8,008		(3	)		—		—			8,008		(3	)
	Commercial paper		3,491		(1	)		—		—			3,491		(1	)
	Total	$	28,045	$	(30	)	$	15,780	$	(25	)	$	43,825	$	(55	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis	'
	The following table presents the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis as of March 31, 2014 and December 31, 2013 (in thousands):
		Fair Value Measurements at March 31, 2014
		Quoted Price in		Significant Other		Significant		Total
		Active Markets		Observable Inputs		Unobservable
		for Identical Assets		(Level 2)		Inputs
		(Level 1)				(Level 3)
	Assets:
	Cash equivalents:
	Money market funds	$	38,211	$	—	$	—	$	38,211
	Total cash equivalents	$	38,211	$	—	$	—	$	38,211
	Available-for-sale securities:
	Short-term:
	Certificates of deposit	$	—	$	12,435	$	—	$	12,435
	Commercial paper		—		3,495		—		3,495
	Corporate notes		—		16,924		—		16,924
	U.S. Government agency securities		—		8,007		—		8,007
	Total short-term investments		—		40,861		—		40,861
	Long-term:
	Certificates of deposit		—		1,882		—		1,882
	Corporate notes		—		1,983		—		1,983
	Total long-term investments		—		3,865		—		3,865
	Total available-for-sale securities	$	—	$	44,726	$	—	$	44,726
		Fair Value Measurements at December 31, 2013
		Quoted Price in		Significant Other		Significant		Total
		Active Markets		Observable Inputs		Unobservable
		for Identical Assets		(Level 2)		Inputs
		(Level 1)				(Level 3)
	Assets:
	Cash equivalents:
	Money market funds	$	38,506	$	—	$	—	$	38,506
	Certificates of deposit		—		480		—		480
	Total cash equivalents	$	38,506	$	480	$	—	$	38,986
	Available-for-sale securities:
	Short-term:
	Certificates of deposit	$	—	$	10,507	$	—	$	10,507
	Commercial paper		—		3,491		—		3,491
	Corporate notes		—		6,039		—		6,039
	U.S. Government agency securities		—		8,008		—		8,008
	Total short-term investments		—		28,045		—		28,045
	Long-term:
	Certificates of deposit		—		2,836		—		2,836
	Corporate notes		—		12,944		—		12,944
	Total long-term investments		—		15,780		—		15,780
	Total available-for-sale securities	$	—	$	43,825	$	—	$	43,825
Carrying Value and Estimated Fair Value of Company's Notes Payable	'
	The following table presents the carrying value and estimated fair value of the Company’s notes payable as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014
		Carrying		Estimated
		Value		Fair Value
	April and September 2012 Notes	$	7,037	$	7,517
		December 31, 2013
		Carrying		Estimated
		Value		Fair Value
	April and September 2012 Notes	$	8,273	$	8,860

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Components of Inventories	'
	The following table represents the components of inventories (in thousands):
		March 31,		December 31,
		2014		2013
	Raw Materials	$	149	$	697
	Work-in-process		317		—
	Finished goods		2,359		2,816
	Total	$	2,825	$	3,513

Intangible_Asset_Tables

Intangible Asset (Tables)	3 Months Ended
	Mar. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]	'
Schedule of Expected Amortization Expense	'
	Estimated aggregate amortization expense for each of the five succeeding years ending December 31 is as follows (in thousands):
		2014		2015		2016		2017		2018
	Amortization expense	$	4,053	$	3,294	$	1,157	$	1,048	$	1,012

Property_and_Equipment_Tables

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2014
Property Plant And Equipment [Abstract]	'
Components of Property and Equipment	'
	The following table represents the components of property and equipment (in thousands):
		March 31,			December 31,
		2014			2013
	Computers and Software	$	839		$	563
	Furniture and Fixtures		320			320
	Office Equipment		53			53
	Capital work in progress		17			264
			1,229			1,200
	Less: Accumulated depreciation		(367	)		(264	)
	Total property and equipment, net	$	862		$	936

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2014
Payables And Accruals [Abstract]	'
Components of Accrued Liabilities	'
	The following table represents the components of accrued liabilities (in thousands):
		March 31,		December 31,
		2014		2013
	Pre-clinical and clinical trial expenses	$	244	$	246
	Payroll and related expenses		1,691		4,278
	Gross to net sales accruals		5,850		5,235
	Royalty payable		1,247		1,154
	Legal accrual		598		45
	Taxes payable		245		326
	Interest payable		52		61
	Other		1,068		842
	Total	$	10,995	$	12,187

Warrants_Tables

Warrants (Tables)	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Summary of Outstanding Warrants and Corresponding Exercise Price	'
	The following table summarizes the outstanding warrants and the corresponding exercise price as of March 31, 2014 and December 31, 2013:
		Number of Shares Outstanding
		March 31,		December 31,		Per Share
		2014		2013		Exercise Price
	October 2007 common stock warrants		274		274	$	1,913.05
	Total		274		274

Equity_Incentive_Plan_and_Stoc1

Equity Incentive Plan and Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Allocation of Stock-Based Compensation Expense	'
	Total stock-based compensation expense related to options granted was allocated as follows (in thousands):
		Three Months Ended
		March 31,
		2014		2013
	Cost of sales	$	2	$	1
	Research and development		147		91
	Selling general and administrative		1,219		413
	Total	$	1,368	$	505

Net_Income_Loss_per_Share_of_C1

Net Income (Loss) per Share of Common Stock (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Net Income (Loss) Per Share of Common Stock	'
	The following table sets forth the computation of basic and diluted net income (loss) per share of common stock for the periods indicated (in thousands, except share and per share amounts):
		Three Months Ended
		March 31,
		2014		2013
	Net income (loss) per share
	Numerator:
	Net income (loss) attributable to common stockholders	$	1,259	$	(8,975	)
	Denominator:
	Weighted-average number of common shares outstanding – basic		20,191,190		17,366,848
	Dilutive effect of stock-options and awards		1,327,336		—
	Weighted average common shares outstanding – dilutive		21,518,526		17,366,848
	Net income (loss) per share:
	Basic	$	0.06	$	(0.52	)
	Diluted	$	0.06	$	(0.52	)
Antidilutive Securities Excluded from Computation of Earnings Per Share	'
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income (loss) per share, as the effect of including them would have been antidilutive:
		Three Months Ended
		March 31,
		2014		2013
	Stock options		1,181,650		2,112,455
	October 2007, April 2008 and 2012 common stock warrants		274		38,261
	Total		1,181,924		2,150,716

Formation_and_Business_of_the_1

Formation and Business of the Company - Additional Information (Detail) (USD $)	3 Months Ended				0 Months Ended
	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Aug. 14, 2013	Mar. 13, 2013
					Follow-on offering
Nature Of Operations [Line Items]	'	'	'	'	'
Net proceeds from public offering	$64,488,000	'	'	'	$63,700,000
Underwriting discounts and commissions	'	'	'	'	4,100,000
Other offering expenses	'	'	'	'	800,000
Aggregate offering price	'	'	'	150,000,000	'
Common stock shares sold by selling stockholders	'	'	'	8,727,000	'
Aggregate offering price under sales agreement	'	'	'	50,000,000	'
Accumulated deficit	'	($121,111,000)	($122,370,000)	'	'

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended			3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	31-May-13	Mar. 31, 2014	Mar. 31, 2013
	Segment		Store	United States	Canada and Europe	BUPHENYL	BUPHENYL	RAVICTI	RAVICTI
	Store								United States
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'	'	'	'	'	'
Number of operating segments	1	'	'	'	'	'	'	'	'
Net product revenue	$19,483,000	$783,000	'	$18,000,000	$1,500,000	$4,000,000	'	$15,500,000	$800,000
Credit losses on accounts receivable	0	'	'	'	'	'	'	'	'
Percentage of domestic accounts receivable	64.00%	'	'	'	'	'	'	'	'
Percentage of accounts receivable by international distributor	12.00%	'	'	'	'	'	'	'	'
Allowances for doubtful accounts	0	'	'	'	'	'	'	'	'
Acquisition of inventory	'	'	'	'	'	'	$3,900,000	'	'
Number of specialty pharmacies distributions made	'	'	2	'	'	'	'	'	'
Percentage of Medicare Part D insurance coverage gap to eligible patients	50.00%	'	'	'	'	'	'	'	'

Collaboration_Agreement_with_U1

Collaboration Agreement with Ucyclyd Pharma, Inc. - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2014	Mar. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Purchase option exercise period	'90 days	'	'
Purchase price for AMMONUL and BUPHENYL	$22	'	'
Monthly payments	'	'	0.5
Purchase price to retain product rights	'	32	'
Net payment to be received for purchase transaction	'	11	'
Cash paid to Ucyclyd for BUPHENYL product rights	'	19	'
Cash due to Ucyclyd for inventory	'	2	'
Purchase agreement with Ucyclyd	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Payment under purchase agreement	6	'	'
Purchase agreement with Ucyclyd | RAVICTI	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Payment under purchase agreement	5.7	'	'
Purchase agreement with Ucyclyd | RAVICTI | Scenario One	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Maximum amount of regulatory milestones, product approval	15.8	'	'
Regulatory milestones, product approval, description	'	'Regulatory milestones related to approval of GPB in HE	'
Purchase agreement with Ucyclyd | RAVICTI | Scenario Two	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Regulatory milestones, product approval, description	'	'Regulatory milestones approval of GPB in indications other than UCD or HE	'
Maximum amount of regulatory milestones, approval in other indications	7.3	'	'
Purchase agreement with Ucyclyd | RAVICTI | Scenario Three	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Regulatory milestones, product approval, description	'	'Net sales milestones if GPB is approved for use in indications other than UCD (such as HE) and all annual sales targets are reached	'
Maximum amount of regulatory milestones, approval in other indications	38.8	'	'
Purchase agreement with Ucyclyd | BUPHENYL and AMMONUL	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'
Option to purchase rights to BUPHENYL and AMMONUL	$0.30	'	'

Schedule_of_Investments_by_Con

Schedule of Investments by Contractual Maturity (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity Year One	$40,867	$28,075
Contractual Maturity Year Two	3,869	15,805
Contractual Maturity, Total Book Value	44,736	43,880
Unrealized Gain (loss)	-10	-55
Aggregate Fair Value	44,726	43,825
Certificates of deposit	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity Year One	12,445	10,525
Contractual Maturity Year Two	1,885	2,845
Contractual Maturity, Total Book Value	14,330	13,370
Unrealized Gain (loss)	-13	-27
Aggregate Fair Value	14,317	13,343
Corporate notes	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity Year One	16,921	6,047
Contractual Maturity Year Two	1,984	12,960
Contractual Maturity, Total Book Value	18,905	19,007
Unrealized Gain (loss)	2	-24
Aggregate Fair Value	18,907	18,983
U.S. Government agency securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity Year One	8,007	8,011
Contractual Maturity Year Two	'	'
Contractual Maturity, Total Book Value	8,007	8,011
Unrealized Gain (loss)	'	-3
Aggregate Fair Value	8,007	8,008
Commercial paper	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity Year One	3,494	3,492
Contractual Maturity Year Two	'	'
Contractual Maturity, Total Book Value	3,494	3,492
Unrealized Gain (loss)	1	-1
Aggregate Fair Value	$3,495	$3,491

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
Other-than-temporary impairments	$0

Schedule_of_Unrealized_Losses_

Schedule of Unrealized Losses and Related Fair Value of Investments with Unrealized Losses (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Less Than 12 Months to Maturity, Aggregate Fair Value	$40,861	$28,045
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	-6	-30
12 Months or More to Maturity, Aggregate Fair Value	3,865	15,780
12 Months or More to Maturity, Unrealized Loss	-4	-25
Aggregate Fair Value, Total	44,726	43,825
Unrealized Gain (loss), Total	-10	-55
Certificates of deposit	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less Than 12 Months to Maturity, Aggregate Fair Value	12,435	10,507
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	-10	-18
12 Months or More to Maturity, Aggregate Fair Value	1,882	2,836
12 Months or More to Maturity, Unrealized Loss	-3	-9
Aggregate Fair Value, Total	14,317	13,343
Unrealized Gain (loss), Total	-13	-27
Corporate notes	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less Than 12 Months to Maturity, Aggregate Fair Value	16,924	6,039
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	3	-8
12 Months or More to Maturity, Aggregate Fair Value	1,983	12,944
12 Months or More to Maturity, Unrealized Loss	-1	-16
Aggregate Fair Value, Total	18,907	18,983
Unrealized Gain (loss), Total	2	-24
U.S. Government agency securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less Than 12 Months to Maturity, Aggregate Fair Value	8,007	8,008
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	'	-3
12 Months or More to Maturity, Aggregate Fair Value	'	'
12 Months or More to Maturity, Unrealized Loss	'	'
Aggregate Fair Value, Total	8,007	8,008
Unrealized Gain (loss), Total	'	-3
Commercial paper	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less Than 12 Months to Maturity, Aggregate Fair Value	3,495	3,491
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	1	-1
12 Months or More to Maturity, Aggregate Fair Value	'	'
12 Months or More to Maturity, Unrealized Loss	'	'
Aggregate Fair Value, Total	3,495	3,491
Unrealized Gain (loss), Total	$1	($1)

Hierarchy_for_Assets_and_Liabi

Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	$38,211	$38,986
Fair value of available-for-sale securities	44,726	43,825
Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	'	480
Fair value of available-for-sale securities	14,317	13,343
Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	3,495	3,491
Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	18,907	18,983
U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	8,007	8,008
Available-for-sale securities, Short-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	40,861	28,045
Available-for-sale securities, Short-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	12,435	10,507
Available-for-sale securities, Short-term | Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	3,495	3,491
Available-for-sale securities, Short-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	16,924	6,039
Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	8,007	8,008
Available-for-sale securities, Long-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	3,865	15,780
Available-for-sale securities, Long-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	1,882	2,836
Available-for-sale securities, Long-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	1,983	12,944
Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	38,211	38,506
Quoted Prices in Active Markets for Identical Items (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	38,211	38,506
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Long-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Long-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Long-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	38,211	38,506
Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	'	480
Fair value of available-for-sale securities	44,726	43,825
Significant Other Observable Inputs (Level 2) | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	'	480
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Short-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	40,861	28,045
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Short-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	12,435	10,507
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Short-term | Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	3,495	3,491
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Short-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	16,924	6,039
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	8,007	8,008
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Long-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	3,865	15,780
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Long-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	1,882	2,836
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Long-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	1,983	12,944
Significant Other Observable Inputs (Level 2) | Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	'	'
Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Long-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Long-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Long-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash equivalents	'	'

Carrying_Value_and_Estimated_F

Carrying Value and Estimated Fair Value of Company's Notes Payable (Detail) (April and September 2012 Notes, USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Carrying Value	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total	$7,037	$8,273
Estimated Fair Value	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total	$7,517	$8,860

Components_of_Inventories_Deta

Components of Inventories (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw Materials	$149	$697
Work-in-process	317	'
Finished goods	2,359	2,816
Total	$2,825	$3,513

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (BUPHENYL, USD $)	31-May-13
In Millions, unless otherwise specified
BUPHENYL	'
Inventory [Line Items]	'
Remaining inventory at balance sheet date	$3.90

Intangible_Asset_Additional_In

Intangible Asset - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Finite-Lived Intangible Assets [Line Items]	'
Amortization of intangible asset	$1,014,000
BUPHENYL	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible asset-BUPHENYL product rights	$16,500,000
Estimated useful life of intangible assets	'10 years

Schedule_of_Expected_Amortizat

Schedule of Expected Amortization Expense (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]	'
2014	$4,053
2015	3,294
2016	1,157
2017	1,048
2018	$1,012

Components_of_Property_and_Equ

Components of Property and Equipment (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$1,229	$1,200
Less: Accumulated depreciation	-367	-264
Total property and equipment, net	862	936
Computers and Software	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	839	563
Furniture and Fixtures	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	320	320
Office Equipment	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	53	53
Capital work in progress	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$17	$264

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Property Plant And Equipment [Abstract]	'	'
Depreciation expense	$100,000	$19,000

Components_of_Accrued_Liabilit

Components of Accrued Liabilities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables And Accruals [Abstract]	'	'
Pre-clinical and clinical trial expenses	$244	$246
Payroll and related expenses	1,691	4,278
Gross to net sales accruals	5,850	5,235
Royalty payable	1,247	1,154
Legal accrual	598	45
Taxes payable	245	326
Interest payable	52	61
Other	1,068	842
Accrued liabilities	$10,995	$12,187

Notes_Payable_Additional_Infor

Notes Payable - Additional Information (Detail) (USD $)	3 Months Ended			1 Months Ended	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Apr. 30, 2012	Sep. 30, 2012	Mar. 31, 2014	Mar. 31, 2013
	April 2012 Notes Payable	April 2012 Notes Payable	April 2012 Notes Payable	September 2012 Notes Payable	September 2012 Notes Payable	September 2012 Notes Payable
Debt Instrument [Line Items]	'	'	'	'	'	'
Aggregate principal amount of notes issued	'	'	$10	'	'	'
Stated interest rate on notes	8.88%	'	'	'	8.88%	'
Interest only payment period	'9 months	'	'	'	'9 months	'
Payment of loan principal and interest	'27 months	'	'	'	'27 months	'
Period for monthly financials and compliance certificate	'30 days	'	'	'	'	'
Period for annual audited financial report	'180 days	'	'	'	'	'
Number of warrants issued	'	'	75,974	8,408	'	'
Exercise price of warrants	'	'	4.08	5.05	'	'
Final payment due as a percentage of principal loan amount	6.50%	'	'	'	6.50%	'
Sale of equity securities or debt, minimum amount for term loan	30	'	'	'	'	'
Bank Term Loan	2.5	'	'	'	'	'
Additional borrowing	'	'	'	2.5	'	'
Percentage in addition to Treasury rate, term loan	'	'	'	'	8.50%	'
Amortization of debt discount	$0.10	$0.10	'	'	$0.10	$0.10

Warrants_Additional_Informatio

Warrants - Additional Information (Detail) (October 2007 Common Stock Warrants)	3 Months Ended
	Mar. 31, 2014	Oct. 31, 2007
October 2007 Common Stock Warrants	'	'
Class of Warrant or Right [Line Items]	'	'
Number of warrants issued	'	274
Exercise price of warrants	1,913.05	'
Expiration date of warrants	'October 2017	'

Summary_of_Outstanding_Warrant

Summary of Outstanding Warrants and Corresponding Exercise Price (Detail)	Mar. 31, 2014	Dec. 31, 2013
Class of Warrant or Right [Line Items]	'	'
Number of Shares Outstanding	274	274
October 2007 Common Stock Warrants	'	'
Class of Warrant or Right [Line Items]	'	'
Number of Shares Outstanding	274	274
Per Share Exercise Price	1,913.05	'

Equity_Incentive_Plan_and_Stoc2

Equity Incentive Plan and Stock-Based Compensation - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended			3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
			2012 Plan	2006 Plan	Inventories	Inventories	Performance RSU's
							2012 Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'	'	'	'
Shares available for issuance under plan	880,495	880,495	'	'	'	'	'
Share options outstanding under plan	'	'	1,610,436	1,463,325	'	'	'
Restricted stock units outstanding under plan	'	'	114,753	'	'	'	'
Restricted stock units, Granted	'	'	101,253	'	'	'	1,500
Options granted during period	'	512,105	'	'	'	'	'
Option exercise price, minimum	'	$25.80	'	'	'	'	'
Option exercise price, maximum	'	$31	'	'	'	'	'
Increase in shares approved for issuance under plan	'	805,485	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost	$100,000	'	'	'	'	'	'
Stock-based compensation capitalized into inventories	'	'	'	'	$8,000	$9,000	'

Allocation_of_StockBased_Compe

Allocation of Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expenses related to employees	$1,368	$505
Cost of sales	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expenses related to employees	2	1
Research and development	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expenses related to employees	147	91
Selling general and administrative	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expenses related to employees	$1,219	$413

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Tax Credit Carryforward [Line Items]	'	'
Income tax expense or benefit	$88,000	'
Interest or penalties accrued	0	'
United States	'	'
Tax Credit Carryforward [Line Items]	'	'
Net operating loss carryforwards	'	72,500,000
Operating loss expirations	'Begin to expire in 2026	'
United States | Research and development tax credit carryforward	'	'
Tax Credit Carryforward [Line Items]	'	'
Tax credit carryforward	18,000,000	'
United States | Federal Orphan Drug Credit | Research and development tax credit carryforward	'	'
Tax Credit Carryforward [Line Items]	'	'
Tax credit carryforward	17,400,000	'
California	'	'
Tax Credit Carryforward [Line Items]	'	'
Net operating loss carryforwards	'	$112,500,000
Operating loss expirations	'Begin to expire in 2016	'

Recovered_Sheet1

Net Income (Loss) Per Share of Common Stock (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net income (loss) per share Numerator:	'	'
Net income (loss) attributable to common stockholders	$1,259	($8,975)
Denominator:	'	'
Basic	20,191,190	17,366,848
Dilutive effect of stock-options and awards	1,327,336	'
Diluted	21,518,526	17,366,848
Net income (loss) per share:	'	'
Basic	$0.06	($0.52)
Diluted	$0.06	($0.52)

Antidilutive_Securities_Exclud

Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Potentially dilutive securities excluded from the computation of diluted net loss per share	1,181,924	2,150,716
Stock options	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Potentially dilutive securities excluded from the computation of diluted net loss per share	1,181,650	2,112,455
Common stock warrants	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Potentially dilutive securities excluded from the computation of diluted net loss per share	274	38,261

Related_Party_Transaction_Addi

Related Party Transaction - Additional Information (Detail) (Swedish Orphan Biovitrum AB, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Swedish Orphan Biovitrum AB	'
Related Party Transaction [Line Items]	'
Sales recognized	$0.30
Accounts receivable from SOBI	$0.30

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Andromeda, USD $)	3 Months Ended	0 Months Ended		0 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Apr. 23, 2014	Apr. 23, 2014	Apr. 23, 2014	Apr. 23, 2014	Apr. 23, 2014
		Subsequent Events	Subsequent Events	Subsequent Events	Subsequent Events	Subsequent Events
			Potential global regulatory and approval milestones	Commercial milestones	Tiered contingent sales payments	Tiered contingent sales payments
					Minimum	Maximum
Subsequent Event [Line Items]	'	'	'	'	'	'
The date a law suit was filed against Par Pharmaceutical, Inc. to obtain a stay of FDA's approval of Par's ANDA	23-Apr-14	'	'	'	'	'
Potential cash payments	'	$12.50	'	'	'	'
Common stock, number of shares issuable	'	312,869	'	'	'	'
Common stock, value of shares issuable	'	7.85	'	'	'	'
Common stock, average closing stock price per share	'	$25.09	'	'	'	'
Contingent payments on acquisition	'	'	120	430	'	'
Annual worldwide net sales	'	'	'	$450	$300	$1,200
Percentage of contingent sales payment	'	'	'	'	10.00%	17.00%
Percentage of sales by distributors in certain territories	'	25.00%	'	'	'	'