Hyperion Therapeutics (HPTX) 10-Q 6 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	HPTX
Entity Registrant Name	HYPERION THERAPEUTICS INC
Entity Central Index Key	1386858
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		20,976,592

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets
Cash and cash equivalents	$88,894	$102,796
Short-term investments	39,742	34,487
Accounts receivable, net	21,548	14,864
Inventories, net	5,597	4,621
Prepaid expenses and other current assets	2,686	2,632
Total current assets	158,467	159,400
Long-term investments	25,014	9,226
Property and equipment, net	1,071	1,116
Intangible asset, net	7,923	8,816
Other non-current assets	2,555	1,858
Total assets	195,030	180,416
Current liabilities
Accounts payable	9,478	4,669
Accrued liabilities	26,614	25,509
Deferred revenue	240	224
Notes payable, current portion	1,529
Total current liabilities	37,861	30,402
Notes payable, net of current portion	16,663	18,124
Deferred rent	326	338
Total liabilities	54,850	48,864
Commitments and contingencies (Note 13)
Stockholders' equity
Preferred stock, par value $0.0001 - 10,000,000 shares authorized at March 31, 2015 and December 31, 2014; none issued and outstanding
Common stock, par value $0.0001 - 100,000,000 shares authorized at March 31, 2015 and December 31, 2014; 20,971,678 and 20,747,013 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	2	2
Additional paid-in capital	261,622	260,225
Accumulated other comprehensive loss	-35	-50
Accumulated deficit	-121,409	-128,625
Total stockholders' equity	140,180	131,552
Total liabilities and stockholders' equity	$195,030	$180,416

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
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, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	20,971,678	20,747,013
Common stock, shares outstanding	20,971,678	20,747,013

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Net product revenue	$31,193	$19,483
Costs and expenses:
Cost of sales	3,833	2,382
Research and development	6,799	3,217
Selling, general and administrative	14,976	11,171
Amortization of intangible asset	893	1,014
Total costs and expenses	26,501	17,784
Income from operations	4,692	1,699
Interest income	160	138
Interest expense	-245	-300
Other income (expense), net (Notes 4 and 10)	4,164	-190
Income before income taxes	8,771	1,347
Income tax expense	1,555	88
Net income	$7,216	$1,259
Net income per share:
Basic	$0.35	$0.06
Diluted	$0.33	$0.06
Weighted average number of shares used to compute net income per share of common stock:
Basic	20,780,059	20,191,190
Diluted	22,079,460	21,518,526

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$7,216	$1,259
Other comprehensive income:
Unrealized gain on investments arising during the period	15	45
Other comprehensive income	15	45
Comprehensive income	$7,231	$1,304

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities
Net income	$7,216	$1,259
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	124	103
Loss on disposal of fixed asset	18
Amortization of debt discount	67	139
Stock-based compensation expense	2,361	1,366
Amortization of intangible asset	893	1,014
Change in acquisition related contingency (Note 10)	-4,115
Amortization of discount on available-for-sale investments	97	104
Unrealized loss on foreign currency remeasurement adjustments	4
Excess tax benefit from stock-based compensation	-124	-44
Changes in assets and liabilities
Accounts receivable	-6,688	2,065
Inventories	-929	696
Prepaid expenses and other assets	-751	302
Accounts payable	4,809	747
Deferred revenue	16	195
Accrued liabilities and other	2,615	-1,150
Deferred rent	-12	180
Net cash provided by operating activities	5,601	6,976
Cash flows from investing activities
Acquisition of property and equipment	-97	-29
Purchase of available-for-sale investments	-34,415	-1,440
Maturity of available-for-sale investments	13,290	480
Net cash used in investing activities	-21,222	-989
Cash flows from financing activities
Proceeds from issuance of common stock from stock option exercises	1,595	887
Income tax benefit on exercise of stock options	124	44
Principal payments under notes payable		-1,367
Net cash provided by (used in) financing activities	1,719	-436
Net increase (decrease) in cash and cash equivalents	-13,902	5,551
Cash and cash equivalents, beginning of period	102,796	74,232
Cash and cash equivalents, end of period	88,894	79,783
Supplemental cash flow information
Cash paid for interest	180	171
Cash paid for income tax	1,073
Stock-based compensation capitalized into inventories	47	8
Supplemental disclosure of noncash investing and financing activities
Unrealized gain on available-for-sale investments	15	45
Deferred gain (Note 4)	$2,595

Formation_and_Business_of_the_

Formation and Business of the Company	3 Months Ended
	Mar. 31, 2015
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 is a commercial biopharmaceutical company focused on the development and commercialization of novel therapeutics to treat disorders in the areas of orphan diseases. The Company’s products RAVICTI ® (glycerol phenylbutyrate) Oral liquid, BUPHENYL ® and AMMONAPS ® (sodium phenylbutyrate) Tablets and Powder, are designed to lower ammonia in the blood. Ammonia is produced in the intestine after a person eats protein and is normally detoxified in the liver by conversion to urea. Elevated levels of ammonia are potentially toxic and can lead to severe medical complications which may include death. The Company developed RAVICTI, which was launched during the first quarter of 2013, to treat most urea cycle disorders (“UCD”) and is developing glycerol phenylbutyrate (“GPB”), the active pharmaceutical ingredient in RAVICTI, to treat hepatic encephalopathy (“HE”). UCD and HE are diseases in which blood ammonia is elevated. 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 its conversion to urea. HE may develop in some patients with liver scarring, known as cirrhosis, or acute liver failure and is a chronic complication of cirrhosis which fluctuates in severity and may lead to serious neurological damage.
	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, 2015, there were no sales of any securities registered pursuant to the shelf registration statement.
	At March 31, 2015, the Company had an accumulated deficit of $121.4 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.
	On March 29, 2015, Horizon Pharma, Inc. (“Horizon”) and the Company entered into a definitive Agreement and the Plan of Merger (the “Merger Agreement”), pursuant to which Horizon will commence an offer (the “Offer”) to acquire all the outstanding shares of the Company for $46.00 per share in cash, without interest, subject to any withholding of taxes. The Completion of the Offer is subject to several conditions, including (i) there shall have been validly tendered and not validly withdrawn Shares that represent one more than 50% of the sum of (A) the total number of Shares outstanding at the time of the expiration of the Offer plus (B) the aggregate number of Shares issuable to holders of stock options of the Company and warrants to purchase shares of common stock of the Company from which the Company has received notices of exercise prior to the consummation of the Offer (and as to which Shares have not yet been issued to such exercising holders of the Company’s Options); (ii) the expiration or termination of any applicable waiting period relating to the Offer under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended; (iii) the absence of a material adverse effect on the Company; (iv) subject to certain materiality exceptions, the truth and accuracy of certain representations and warranties of the Company contained in the Merger Agreement; (v) Horizon’s receipt of debt financing pursuant to the debt commitment letter (or any alternative financing) or Horizon’s receipt of confirmation from its lenders the debt financing (or an alternative financing) will be available at the consummation of the Offer; and (vi) certain other customary conditions. The offer will expire at 12:01 A.M. on May 7, 2015.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
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, 2015, 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, 2014.
	Principles of Consolidation
	The consolidated financial statements include the Company’s accounts and those of its wholly-owned subsidiaries: Hyperion Therapeutics Ltd., Hyperion Therapeutics Ireland Holding Ltd., Hyperion Therapeutics Ireland Operating Ltd., Hyperion Therapeutics Israel Holding Corp. Ltd., Hyperion Therapeutics International Holding Co. (formerly Penville Limited) and Andromeda Biotech Ltd. All intercompany accounts and transactions have been eliminated.
	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.
	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, 2015, there were no credit losses on the Company’s accounts receivable. As of March 31, 2015 and December 31, 2014, the specialty distributor in the United States accounted for 94% and 87%, respectively, of the accounts receivable balance. As of March 31, 2015 no international distributor accounted for more than 10% of the accounts receivable balance. At December 31, 2014, one international distributor accounted for 10% of the accounts receivable balance.
	The specialty distributor in the U.S. accounted for 90% and 92%, respectively, of the net product revenue for the three months ended March 31, 2015 and March 31, 2014. No other distributor in the U.S. accounted for more than 10% of the net product revenue for the three month periods ended March 31, 2015 and 2014, respectively.
	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, accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of long-term investments, the acquisition-related contingent consideration 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. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. 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.
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents include money market funds and various deposit accounts.
	Investments
	The Company determines the appropriate classification of its investments in debt and equity securities at the time of purchase. All of the Company’s securities are classified as available-for-sale and reported in short-term investments or long-term investments based on maturity dates and whether such assets are reasonably expected to be realized in cash or sold or consumed during the normal cycle of business. Available-for-sale investments are recorded at fair value, with unrealized gains or losses included in Accumulated Other Comprehensive Loss on the Company’s Consolidated Balance Sheets, exclusive of other-than-temporary impairment losses, if any. Short-term and long-term investments are comprised of corporate notes, commercial paper, U.S. federal government agency securities and certificates of deposit.
	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, 2015, 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”.
	Intangible Assets
	Intangible assets are recorded at acquisition cost less accumulated amortization and impairment. Intangible asset with finite lives are amortized over their 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.
	Preclinical and Clinical Trial Accruals
	The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites as well as estimates for the services received and efforts expended pursuant to contracts with multiple research institutions and clinical research organizations that conduct and manage preclinical and clinical trials on the Company’s behalf. The Company accrues expenses related to clinical trials based on contracted amounts applied to the level of patient enrollment and activity according to the protocol. If timelines or contracts are modified based upon changes in the clinical trial protocol or scope of work to be performed, the Company modifies the estimates of accrued expenses accordingly. To date, the Company has had no significant adjustments to accrued preclinical and clinical trial expenses.
	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. Prior to June 2014, revenue from the sale of RAVICTI was recognized based on the amount of product sold through to the end user consumer. Starting June 2014, the Company could reasonably estimate and determine sales allowances, therefore the Company began recognizing RAVICTI revenue at the point of sale to the specialty distributor.
	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 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, has been utilized.
	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 Remeasurements
	The Company has cash and accounts receivable denominated in foreign currency that are remeasured at the rate of exchange in effect on the balance sheet date. Revenue and expenses denominated in foreign currency are remeasured at the weighted average rate of exchange prevailing during the period. Any gains and losses resulting from foreign currency remeasurement are included in other income (expense)-net in the condensed consolidated statements of operations.
	Comprehensive Income
	Comprehensive income is comprised of net income and other comprehensive income. Other comprehensive income includes changes in stockholders’ equity that are excluded from net income, specifically changes in unrealized gains and losses on the Company’s available-for-sale securities.
	Net Income per Share of Common Stock
	Basic earnings per share is computed by dividing the net income 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 May 2014, FASB issued Accounting Standards Update 2014-09 (ASU 2014-09), Revenue from Contracts with Customers. ASU 2014-09 will supersede the revenue recognition requirements in Revenue Recognition (Topic 605) and requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period, which for the Company is January 1, 2017. Early adoption is not permitted. The Company is currently evaluating the potential impact the adoption of ASU 2014-09 will have on the Company’s condensed consolidated financial statements.
	In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis (Topic 810) and requires entities to reevaluate under the revised consolidation model if they should consolidate certain legal entities. ASU 2015-02 is effective for annual and interim periods beginning on or after December 15, 2015 and early adoption is permitted. The Company does not expect the adoption of ASU 2015-02 to have a material effect upon its condensed consolidated financial statements.
	In April 2015, the FASB issued ASU 2015-03, Interest-Imputation of Interest (Subtopic 835-30). ASU 2015-03 simplifies the presentation of debt issuance costs. ASU 2015-03 is effective for annual and interim periods beginning on or after December 15, 2015 and early adoption is permitted. The Company does not expect the adoption of ASU 2015-03 to have a material effect upon its financial statements.

Collaboration_Agreement_with_U

Collaboration Agreement with Ucyclyd Pharma, Inc.	3 Months Ended
	Mar. 31, 2015
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.
	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.

Completion_of_Phase_3_Clinical

Completion of Phase 3 Clinical Trial, Option and Mutual Release Agreement	3 Months Ended
	Mar. 31, 2015
Text Block [Abstract]
Completion of Phase 3 Clinical Trial, Option and Mutual Release Agreement	4	Completion of Phase 3 Clinical Trial, Option and Mutual Release Agreement
	On February 16, 2015 the Company entered into Completion of Phase 3 Clinical Trial, Option and Mutual Release Agreement (“Agreement”) with CBI and Yeda Research and Development Company Ltd (“Yeda”), the company from which Andromeda licenses the underlying DiaPep277 technology (the Company, CBI and Yeda are referred as a “Party” and collectively the “Parties”). Under the Agreement the Parties agreed to the following:
		•	The Parties released the DiaPep277 related claims against one another.
		•	The parties have appointed a steering committee to oversee the completion of the clinical trial with representatives of CBI and Yeda and a non-voting member appointed by the Company.
		•	The Company committed to complete the Phase 3 clinical trial of DiaPep277. The Company’s estimated budget from October 1, 2014 through the completion of the trial remains unchanged at $10.5 million. Any increase to this budget beyond $2.25 million, if incurred as a result of the direction of the steering committee, shall require CBI to reimburse those expenses in shares of the Company’s common stock or cash if shares are not available.
		•	CBI will transfer to the Company $2.5 million in shares of the Company’s common stock it holds, valued at the average closing price of the Company’s common stock for the fifteen trading days ending on February 11, 2015.
		•	The Company granted CBI an option to acquire all of the outstanding stock of Andromeda (“Option”). The Option is exercisable through September 30, 2015 for $3.5 million payable in shares of the Company’s common stock, valued at the average closing price of the Company’s common stock for the fifteen trading days ending on February 11, 2015. In addition, if the Option is exercised, then Andromeda will be obligated to pay the Company future contingent payments if and to the extent it or its shareholders receive revenues or certain other proceeds, which are capped at $36.5 million. This amount, together with the Option exercise price that the Company may receive, approximates the total amount the Company will have invested in Andromeda by the Option exercise date. If CBI does not exercise the option, (i) CBI shall pay the Company $0.4 million in share of the Company’s common stock, valued at the average closing price of the Company’s common stock for the fifteen trading days ending on February 11, 2015, and (ii) the underlying DiaPep277 technology will revert to Yeda under the license agreement between Andromeda and Yeda.
	The Company determined that the Agreement should be evaluated as a multiple element arrangement in accordance with ASC 605-25 Revenue Recognition — Multiple-Element Arrangements, with each element accounted for individually. Accordingly, the Company recorded the right to receive Initial Shares of the Company’s common stock at its fair value of $2.6 million in the stockholders’ equity and as a deferred gain in accrued liabilities on the Company’s consolidated balance sheet. The Company also determined that the Option to acquire the outstanding stock of Andromeda was a derivative instrument measured at fair value until the Option is exercised or expired with changes in fair value recorded in earnings. There was no significant impact on the Company’s condensed consolidated financial statements as a result of applying fair value measurement to the Option during the period ended March 31, 2015.

Investments

Investments	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investments	5	Investments
	All investments were classified as available-for-sale at March 31, 2015 and December 31, 2014, respectively. The principal amounts of investments by contractual maturity at March 31, 2015 and December 31, 2014 are summarized in the tables below:
			Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
			Period Ending March 31,					Value at		Loss			Fair Value at
								March 31, 2015					March 31, 2015
			2016		2017
	Certificates of deposit		$	24,645	$	6,960		$	31,605	$	(7	)	$	31,598
	Corporate notes			7,700		18,075			25,775		(26	)		25,749
	U.S. government agency securities			3,915		—			3,915		(1	)		3,914
	Commercial paper			3,496		—			3,496		(1	)		3,495
	Total		$	39,756	$	25,035		$	64,791	$	(35	)	$	64,756
			Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
			Years Ending December 31,					Value at		Loss			Fair Value at
								December 31, 2014					December 31, 2014
			2015		2016
	Certificates of deposit		$	18,405	$	6,240		$	24,645	$	(35	)	$	24,610
	Corporate notes			12,613		3,011			15,624		(12	)		15,612
	Commercial paper			3,494		—			3,494		(3	)		3,491
	Total		$	34,512	$	9,251		$	43,763	$	(50	)	$	43,713
	The Company evaluated its investments and determined that there were no other-than-temporary impairments as of March 31, 2015.
	The aggregate amounts of unrealized losses and related fair value of investments with unrealized losses as of March 31, 2015 and December 31, 2014 were as follows:
			Less Than 12 Months to					12 Months or More to					Total at March 31, 2015
			Maturity					Maturity
			Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
			Fair Value		Gain (loss)			Fair Value		Loss			Fair Value		Gain (loss)
	Certificates of deposit		$	24,636	$	(9	)	$	6,962	$	2		$	31,598	$	(7	)
	Corporate notes			7,697		(3	)		18,052		(23	)		25,749		(26	)
	U.S. government agency securities			3,914		(1	)		—		—			3,914		(1	)
	Commercial paper			3,495		(1	)		—		—			3,495		(1	)
	Total		$	39,742	$	(14	)	$	25,014	$	(21	)	$	64,756	$	(35	)
			Less Than 12 Months to					12 Months or More to					Total at December 31, 2014
			Maturity					Maturity
			Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
			Fair Value		Loss			Fair Value		Loss			Fair Value		Loss
	Certificates of deposit		$	18,386	$	(19	)	$	6,224	$	(16	)	$	24,610	$	(35	)
	Corporate notes			12,610		(2	)		3,002		(10	)		15,612		(12	)
	Commercial paper			3,491		(3	)		—		—			3,491		(3	)
	Total		$	34,487	$	(24	)	$	9,226	$	(26	)	$	43,713	$	(50	)

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	6	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, 2015 and December 31, 2014 (in thousands):
			Fair Value Measurements at March 31, 2015
			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		$	38,286	$	—	$	—	$	38,286
	Total cash equivalents		$	38,286	$	—	$	—	$	38,286
	Available-for-sale securities:
	Short-term:
	Certificates of deposit		$	—	$	24,636	$	—	$	24,636
	Commercial paper			—		3,495		—		3,495
	Corporate notes			—		7,697		—		7,697
	U.S. Government agency securities			—		3,914		—		3,914
	Total short-term investments			—		39,742		—		39,742
	Long-term:
	Certificates of deposit			—		6,962		—		6,962
	Corporate notes			—		18,052		—		18,052
	Total long-term investments			—		25,014		—		25,014
	Total available-for-sale securities		$	—	$	64,756	$	—	$	64,756
			Fair Value Measurements at December 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		$	38,532	$	—	$	—	$	38,532
	Certificates of deposit			—		720		—		720
	Total cash equivalents		$	38,532	$	720	$	—	$	39,252
	Available-for-sale securities:
	Short-term:
	Certificates of deposit		$	—	$	18,386	$	—	$	18,386
	Commercial paper			—		3,491		—		3,491
	Corporate notes			—		12,610		—		12,610
	Total short-term investments			—		34,487		—		34,487
	Long-term:
	Certificates of deposit			—		6,224		—		6,224
	Corporate notes			—		3,002		—		3,002
	Total long-term investments			—		9,226		—		9,226
	Total available-for-sale securities		$	—	$	43,713	$	—	$	43,713
	The following table presents the carrying value and estimated fair value of the Company’s notes payable as of March 31, 2015 and December 31, 2014 (in thousands):
			March 31, 2015
			Carrying		Estimated
			Value		Fair Value
	Term Loans		$	16,192	$	16,759
			December 31, 2014
			Carrying		Estimated
			Value		Fair Value
	Term Loans		$	16,124	$	16,746
	Valuation Techniques
	Level 1 Inputs
	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.
	Level 2 Inputs
	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 obtaining market values from other pricing sources and analyzing pricing data in certain instances.
	Level 3 Inputs
	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, 2015
Inventory Disclosure [Abstract]
Inventories	7	Inventories
	The following table represents the components of inventories (in thousands):
			March 31,		December 31,
			2015		2014
	Raw Materials		$	2,556	$	1,787
	Work-in-process			867		543
	Finished goods			2,174		2,291
	Total		$	5,597	$	4,621
	Reserves on the inventory balance was $0.3 million each for the period ended March 31, 2015 and year ended December 31, 2014.

Intangible_Asset

Intangible Asset	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Asset	8	Intangible Asset
	In May 2013, 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 intangible asset is amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefit of the intangible asset is consumed as revenue is generated. The pattern of consumption of the economic benefit is estimated using the future projected cash flow of the intangible asset which is reviewed on a regular basis. The Company estimated the useful life of the BUPHENYL product rights to be 10 years. The average life remaining as of March 31, 2015 is 7.8 years.
	Intangible asset amortization expense was $0.9 million and $1.0 million, respectively for the three months ended March 31, 2015 and March 31, 2014.
	Estimated aggregate amortization expense for each of the five succeeding years ending December 31 is as follows (in thousands):
			2015		2016		2017		2018		2019
	Amortization expense		$	3,571	$	975	$	893	$	871	$	849

Property_and_Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Property and Equipment	9	Property and Equipment
	The following table represents the components of property and equipment (in thousands):
			March 31,			December 31,
			2015			2014
	Computers and Software		$	1,423		$	1,202
	Furniture and Fixtures			320			320
	Office Equipment			53			53
	Capital work in progress			33			181
				1,829			1,756
	Less: Accumulated depreciation			(758	)		(640	)
	Total property and equipment, net		$	1,071		$	1,116
	Depreciation expense for each of the periods ended March 31, 2015 and 2014 was $0.1 million.

Accrued_Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Accrued Liabilities	10	Accrued Liabilities
	The following table represents the components of accrued liabilities (in thousands):
			March 31,		December 31,
			2015		2014
	Clinical and clinical trial expenses		$	1,247	$	2,399
	Payroll and related expenses			2,917		4,134
	Gross to net sales accruals			13,197		10,142
	Royalty payable			2,067		2,080
	Legal accrual			994		410
	Taxes payable			921		563
	Acquisition related accrual (see below)			—		4,615
	Other (Note 4)			5,271		1,166
	Total		$	26,614	$	25,509
	On February 16, 2015, the Company entered into Settlement Agreement and General Release with Evotec International GmbH (“Evotec”) pursuant to which Evotec released its previously asserted claims to a milestone payment from the Company in connection with the acquisition of Andromeda in exchange for a payment of $0.5 million from the Company. As of December 31, 2014, the Company had $4.6 million included in “Accrued liabilities” on the condensed consolidated balance sheets. In the first quarter of 2015, the Company recognized a gain of $4.1 million in “Other income (expense), net” in the condensed consolidated statements of operations resulting from the release of the accrued liabilities.

Notes_Payable

Notes Payable	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Notes Payable	11	Notes Payable
	On July 18, 2014, the Company entered into a new Loan and Security Agreement (the “Loan Agreement”) with Silicon Valley Bank (“SVB”), providing for two tranches of term loans of up to $16.0 million (the “Term Loans”) and a revolving credit line of up to $5.0 million (the “Revolving Loans”). In July 2014, the Company drew down both tranches of the Term Loans, of which approximately $5.8 million was used to pre-pay the Company’s existing April and September 2012 notes payable. In addition, the Company drew down $2.0 million from the revolving line of credit facility. The actual amount of the Revolving Loans that are available from time to time under the Loan Agreement is limited to a borrowing base amount that is determined according to, among other things, a percentage of the value of eligible accounts.
	The Company’s obligations under the Loan Agreement are collateralized by a first priority security interest in substantially all of the Company’s assets, excluding its intellectual property. The Company has also agreed not to pledge or otherwise encumber its intellectual property assets, except that the Company may grant licenses of its intellectual property as set forth in the Loan Agreement.
	The Company is required to pay interest only for the first 18 months of the Term Loans, followed by 30 equal monthly payments of interest and principal. The Term Loans will mature on June 30, 2018. The Revolving Loans will mature on July 18, 2017. The Loan Agreement provides for an interest rate of 4.0% per year on the Term Loans and the prime rate plus 0.75% per year on the Revolving Loans, with a minimum interest requirement on the Revolving Loans. Upon the maturity date of the Term Loans, a final payment fee of 6.75% of the original principal amount of such Term Loans (the “Final Payment”) will be due.
	The Loan Agreement contains customary representations, warranties and covenants (including the requirement to meet one of two financial covenants) by the Company, as well as customary events of default and indemnification obligations of the Company. The financial covenants include maintaining liquidity ratio on a monthly basis and achieving revenue projections on a quarterly basis as defined in the agreement. The Loan Agreement also requires the Company to provide SVB reports and compliance certificate within 30 days of each month end, quarterly financial statements within 45 days of the end of the quarter and annual audited financials within 180 days of each fiscal year-end and annual approved financial projections. 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. Upon an event of default, after any applicable grace or cure period, all amounts owed under the Loan Agreement may be declared due and payable, including the original principal amount of the Loans, the accrued but unpaid interest thereon, the Final Payment and the prepayment fee. In addition, the Loan Agreement also requires the Company to maintain its depository accounts, operating accounts, securities accounts and all foreign exchange transactions with SVB and SVB bank’s affiliates which accounts shall represent at least the lesser of (i) seventy five percent (75%) of the dollar value of the Company and its Subsidiaries’ accounts at all financial institutions or (ii) $40.0 million; provided, however, that the Company’s obligation relating to foreign exchange transactions is subject to SVB providing commercially competitive exchange rates.
	For each of the three month periods ended March 31, 2015 and March 31, 2014, the Company recorded amortization of debt discount of $0.1 million.
	Future minimum payments under the Loan Agreement as of March 31, 2015 are as follows (in thousands):
	Years Ending December 31,
	2015		$	551
	2016			6,822
	2017			8,786
	2018			4,450
	Total future minimum payments		$	20,609
	Less: amount representing unamortized interest			(1,528	)
	Less: amount representing debt discount			(889	)
	Total minimum payments		$	18,192
	Less: current portion			(1,529	)
	Non-current portion		$	16,663

Warrants

Warrants	3 Months Ended
	Mar. 31, 2015
Text Block [Abstract]
Warrants	12	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 were exercisable at $1,913.05 per share and expire in October 2017 (the “October 2007 common stock warrants”). The October 2007 common stock warrants were outstanding as of March 31, 2015 and December 31, 2014.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	13	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.
	On March 17, 2014, the Company received notification of a Paragraph IV certification from the generic drug manufacturer Par Pharmaceutical, Inc. (“Par”) that it had filed an Abbreviated New Drug Application 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 and to obtain a stay of the FDA’s approval of Par’s ANDA. On July 22, 2014, Par filed a motion to dismiss for lack of personal jurisdiction, or in the alternative, a motion to transfer the case to the Southern District of New York. The Company will oppose the motion. On April 29, 2015, Par filed petitions for Inter Partes Review of the ’215 patent and the ’012 patent with the United States Patent and Trademark Office. The petitions allege that the claims of the ’215 patent and ’012 patent are invalid as obvious for reasons similar to those alleged in the ongoing litigation. The United States Patent and Trademark Office has not yet decided whether to institute a review of either patent.

Equity_Incentive_Plan_and_Stoc

Equity Incentive Plan and Stock-Based Compensation	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plan and Stock-Based Compensation	14	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
	On January 1, 2015, 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 829,880 shares. As of March 31, 2015, the Company had 994,222 shares of common stock available for issuance and 1,903,719 options, 388,130 restricted stock units (“RSU’s”) and 8,662 performance stock units (“PSU’s) were outstanding under the 2012 Plan. During the three months ended March 31, 2015, the board of directors approved the grants of 246,700 stock options at exercise prices in the range of $24.94 - $25.97 and 289,127 RSU’s and 8,662 PSU’s 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, 2015, there were 1,204,359 stock options outstanding under the 2006 Plan.
	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, RSU’s and PSU’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,
			2015		2014
	Cost of sales		$	24	$	2
	Research and development			493		147
	Selling general and administrative			1,915		1,219
	Total		$	2,432	$	1,368
	Stock-based compensation of $47,000 and $8,000 was capitalized into inventories for the three months ended March 31, 2015 and 2014, 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, 2015
Income Tax Disclosure [Abstract]
Income Taxes	15	Income Taxes
	At December 31, 2014, the Company had net operating loss carryforwards of approximately $36.4 million and $107.8 million available to reduce future taxable income, if any, for both federal and California state income tax purposes, respectively. In addition, the Company had $67.3 million of Israeli net operating loss carryforwards which do not expire. The net operating loss carryforwards will begin to expire in 2031 and 2028 for federal and state income tax purposes, respectively.
	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 $22.6 million of federal credit carryforwards of which $21.1 million relates to Orphan Drug Credit claims for 2009 through 2014.
	For the period ended March 31, 2015 and 2014, the Company recorded an income tax expense of $1.6 million and $0.1 million, respectively. Expected taxable income in 2015 will largely be offset by federal and state net operating losses and credits.
	There was no interest or penalties accrued through March 31, 2015. 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_per_Share_of_Common

Net Income per Share of Common Stock	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Net Income per Share of Common Stock	16	Net Income per Share of Common Stock
	The following table sets forth the computation of basic and diluted net income per share of common stock for the periods indicated (in thousands, except share and per share amounts):
			Three Months Ended
			March 31,
			2015		2014
	Net income per share
	Numerator:
	Net income attributable to common stockholders		$	7,216	$	1,259
	Denominator:
	Weighted-average number of common shares outstanding – basic			20,780,059		20,191,190
	Dilutive effect of stock-options and awards			1,299,401		1,327,336
	Weighted average common shares outstanding – dilutive			22,079,460		21,518,526
	Net income per share:
	Basic		$	0.35	$	0.06
	Diluted		$	0.33	$	0.06
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income per share, as the effect of including them would have been antidilutive:
			Three Months Ended
			March 31,
			2015		2014
	Stock options			1,443,122		1,181,650
	October 2007 common stock warrants			274		274
	Total			1,443,396		1,181,924

RelatedParty_Transaction

Related-Party Transaction	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related-Party Transaction	17	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, 2015 the Company recognized $1.6 million from sales to SOBI. As of March 31, 2015, trade receivable from SOBI amounted to $0.6 million.

Segment_Reporting

Segment Reporting	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment Reporting	18	Segment Reporting
	The Company operates as one operating segment and uses one measurement of profitability to manage its business.
	Net product revenue for RAVICTI and BUPHENYL for the three months ended March 31, 2015 and 2014 are as follows (in thousands):
			Three Months Ended
			March 31,
			2015		2014
	RAVICTI		$	25,966	$	15,516
	BUPHENYL			5,227		3,967
	Total		$	31,193	$	19,483
	Net product revenue for RAVICTI and BUPHENYL by geographic region are as follows (in thousands):
			Three Months Ended
			March 31,
			2015		2014
	United States		$	28,212	$	17,996
	Canada			1,147		800
	Rest of the world			1,834		687
	Total		$	31,193	$	19,483
	Long lived assets consist of property and equipment which at March 31, 2015 and 2014 are primarily in the U.S.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
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, 2015, 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, 2014.
Principles of Consolidation	Principles of Consolidation
	The consolidated financial statements include the Company’s accounts and those of its wholly-owned subsidiaries: Hyperion Therapeutics Ltd., Hyperion Therapeutics Ireland Holding Ltd., Hyperion Therapeutics Ireland Operating Ltd., Hyperion Therapeutics Israel Holding Corp. Ltd., Hyperion Therapeutics International Holding Co. (formerly Penville Limited) and Andromeda Biotech Ltd. All intercompany accounts and transactions have been eliminated.
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.
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, 2015, there were no credit losses on the Company’s accounts receivable. As of March 31, 2015 and December 31, 2014, the specialty distributor in the United States accounted for 94% and 87%, respectively, of the accounts receivable balance. As of March 31, 2015 no international distributor accounted for more than 10% of the accounts receivable balance. At December 31, 2014, one international distributor accounted for 10% of the accounts receivable balance.
	The specialty distributor in the U.S. accounted for 90% and 92%, respectively, of the net product revenue for the three months ended March 31, 2015 and March 31, 2014. No other distributor in the U.S. accounted for more than 10% of the net product revenue for the three month periods ended March 31, 2015 and 2014, respectively.
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, accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of long-term investments, the acquisition-related contingent consideration 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. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. 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.
Cash and Cash Equivalents	Cash and Cash Equivalents
	The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents include money market funds and various deposit accounts.
Investments	Investments
	The Company determines the appropriate classification of its investments in debt and equity securities at the time of purchase. All of the Company’s securities are classified as available-for-sale and reported in short-term investments or long-term investments based on maturity dates and whether such assets are reasonably expected to be realized in cash or sold or consumed during the normal cycle of business. Available-for-sale investments are recorded at fair value, with unrealized gains or losses included in Accumulated Other Comprehensive Loss on the Company’s Consolidated Balance Sheets, exclusive of other-than-temporary impairment losses, if any. Short-term and long-term investments are comprised of corporate notes, commercial paper, U.S. federal government agency securities and certificates of deposit.
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, 2015, 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”.
Intangible Assets	Intangible Assets
	Intangible assets are recorded at acquisition cost less accumulated amortization and impairment. Intangible asset with finite lives are amortized over their 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.
Preclinical and Clinical Trial Accruals	Preclinical and Clinical Trial Accruals
	The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites as well as estimates for the services received and efforts expended pursuant to contracts with multiple research institutions and clinical research organizations that conduct and manage preclinical and clinical trials on the Company’s behalf. The Company accrues expenses related to clinical trials based on contracted amounts applied to the level of patient enrollment and activity according to the protocol. If timelines or contracts are modified based upon changes in the clinical trial protocol or scope of work to be performed, the Company modifies the estimates of accrued expenses accordingly. To date, the Company has had no significant adjustments to accrued preclinical and clinical trial expenses.
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. Prior to June 2014, revenue from the sale of RAVICTI was recognized based on the amount of product sold through to the end user consumer. Starting June 2014, the Company could reasonably estimate and determine sales allowances, therefore the Company began recognizing RAVICTI revenue at the point of sale to the specialty distributor.
	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 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, has been utilized.
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 Remeasurements	Foreign Currency Remeasurements
	The Company has cash and accounts receivable denominated in foreign currency that are remeasured at the rate of exchange in effect on the balance sheet date. Revenue and expenses denominated in foreign currency are remeasured at the weighted average rate of exchange prevailing during the period. Any gains and losses resulting from foreign currency remeasurement are included in other income (expense)-net in the condensed consolidated statements of operations.
Comprehensive Income	Comprehensive Income
	Comprehensive income is comprised of net income and other comprehensive income. Other comprehensive income includes changes in stockholders’ equity that are excluded from net income, specifically changes in unrealized gains and losses on the Company’s available-for-sale securities.
Net Income per Share of Common Stock	Net Income per Share of Common Stock
	Basic earnings per share is computed by dividing the net income 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 May 2014, FASB issued Accounting Standards Update 2014-09 (ASU 2014-09), Revenue from Contracts with Customers. ASU 2014-09 will supersede the revenue recognition requirements in Revenue Recognition (Topic 605) and requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period, which for the Company is January 1, 2017. Early adoption is not permitted. The Company is currently evaluating the potential impact the adoption of ASU 2014-09 will have on the Company’s condensed consolidated financial statements.
	In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis (Topic 810) and requires entities to reevaluate under the revised consolidation model if they should consolidate certain legal entities. ASU 2015-02 is effective for annual and interim periods beginning on or after December 15, 2015 and early adoption is permitted. The Company does not expect the adoption of ASU 2015-02 to have a material effect upon its condensed consolidated financial statements.
	In April 2015, the FASB issued ASU 2015-03, Interest-Imputation of Interest (Subtopic 835-30). ASU 2015-03 simplifies the presentation of debt issuance costs. ASU 2015-03 is effective for annual and interim periods beginning on or after December 15, 2015 and early adoption is permitted. The Company does not expect the adoption of ASU 2015-03 to have a material effect upon its financial statements.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Schedule of Investments by Contractual Maturity	The principal amounts of investments by contractual maturity at March 31, 2015 and December 31, 2014 are summarized in the tables below:
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Period Ending March 31,					Value at		Loss			Fair Value at
							March 31, 2015					March 31, 2015
		2016		2017
	Certificates of deposit	$	24,645	$	6,960		$	31,605	$	(7	)	$	31,598
	Corporate notes		7,700		18,075			25,775		(26	)		25,749
	U.S. government agency securities		3,915		—			3,915		(1	)		3,914
	Commercial paper		3,496		—			3,496		(1	)		3,495
	Total	$	39,756	$	25,035		$	64,791	$	(35	)	$	64,756
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Years Ending December 31,					Value at		Loss			Fair Value at
							December 31, 2014					December 31, 2014
		2015		2016
	Certificates of deposit	$	18,405	$	6,240		$	24,645	$	(35	)	$	24,610
	Corporate notes		12,613		3,011			15,624		(12	)		15,612
	Commercial paper		3,494		—			3,494		(3	)		3,491
	Total	$	34,512	$	9,251		$	43,763	$	(50	)	$	43,713
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, 2015 and December 31, 2014 were as follows:
		Less Than 12 Months to					12 Months or More to					Total at March 31, 2015
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Gain (loss)			Fair Value		Loss			Fair Value		Gain (loss)
	Certificates of deposit	$	24,636	$	(9	)	$	6,962	$	2		$	31,598	$	(7	)
	Corporate notes		7,697		(3	)		18,052		(23	)		25,749		(26	)
	U.S. government agency securities		3,914		(1	)		—		—			3,914		(1	)
	Commercial paper		3,495		(1	)		—		—			3,495		(1	)
	Total	$	39,742	$	(14	)	$	25,014	$	(21	)	$	64,756	$	(35	)
		Less Than 12 Months to					12 Months or More to					Total at December 31, 2014
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Loss			Fair Value		Loss			Fair Value		Loss
	Certificates of deposit	$	18,386	$	(19	)	$	6,224	$	(16	)	$	24,610	$	(35	)
	Corporate notes		12,610		(2	)		3,002		(10	)		15,612		(12	)
	Commercial paper		3,491		(3	)		—		—			3,491		(3	)
	Total	$	34,487	$	(24	)	$	9,226	$	(26	)	$	43,713	$	(50	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015 and December 31, 2014 (in thousands):
		Fair Value Measurements at March 31, 2015
		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	$	38,286	$	—	$	—	$	38,286
	Total cash equivalents	$	38,286	$	—	$	—	$	38,286
	Available-for-sale securities:
	Short-term:
	Certificates of deposit	$	—	$	24,636	$	—	$	24,636
	Commercial paper		—		3,495		—		3,495
	Corporate notes		—		7,697		—		7,697
	U.S. Government agency securities		—		3,914		—		3,914
	Total short-term investments		—		39,742		—		39,742
	Long-term:
	Certificates of deposit		—		6,962		—		6,962
	Corporate notes		—		18,052		—		18,052
	Total long-term investments		—		25,014		—		25,014
	Total available-for-sale securities	$	—	$	64,756	$	—	$	64,756
		Fair Value Measurements at December 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	$	38,532	$	—	$	—	$	38,532
	Certificates of deposit		—		720		—		720
	Total cash equivalents	$	38,532	$	720	$	—	$	39,252
	Available-for-sale securities:
	Short-term:
	Certificates of deposit	$	—	$	18,386	$	—	$	18,386
	Commercial paper		—		3,491		—		3,491
	Corporate notes		—		12,610		—		12,610
	Total short-term investments		—		34,487		—		34,487
	Long-term:
	Certificates of deposit		—		6,224		—		6,224
	Corporate notes		—		3,002		—		3,002
	Total long-term investments		—		9,226		—		9,226
	Total available-for-sale securities	$	—	$	43,713	$	—	$	43,713
Carrying Value and Estimated Fair Value of Company's Notes Payable and Term Loans	The following table presents the carrying value and estimated fair value of the Company’s notes payable as of March 31, 2015 and December 31, 2014 (in thousands):
		March 31, 2015
		Carrying		Estimated
		Value		Fair Value
	Term Loans	$	16,192	$	16,759
		December 31, 2014
		Carrying		Estimated
		Value		Fair Value
	Term Loans	$	16,124	$	16,746

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Components of Inventories	The following table represents the components of inventories (in thousands):
		March 31,		December 31,
		2015		2014
	Raw Materials	$	2,556	$	1,787
	Work-in-process		867		543
	Finished goods		2,174		2,291
	Total	$	5,597	$	4,621

Intangible_Asset_Tables

Intangible Asset (Tables)	3 Months Ended
	Mar. 31, 2015
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):
		2015		2016		2017		2018		2019
	Amortization expense	$	3,571	$	975	$	893	$	871	$	849

Property_and_Equipment_Tables

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2015
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,
		2015			2014
	Computers and Software	$	1,423		$	1,202
	Furniture and Fixtures		320			320
	Office Equipment		53			53
	Capital work in progress		33			181
			1,829			1,756
	Less: Accumulated depreciation		(758	)		(640	)
	Total property and equipment, net	$	1,071		$	1,116

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Components of Accrued Liabilities	The following table represents the components of accrued liabilities (in thousands):
		March 31,		December 31,
		2015		2014
	Clinical and clinical trial expenses	$	1,247	$	2,399
	Payroll and related expenses		2,917		4,134
	Gross to net sales accruals		13,197		10,142
	Royalty payable		2,067		2,080
	Legal accrual		994		410
	Taxes payable		921		563
	Acquisition related accrual (see below)		—		4,615
	Other (Note 4)		5,271		1,166
	Total	$	26,614	$	25,509

Notes_Payable_Tables

Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Future Minimum Payments Under Loan Agreement	Future minimum payments under the Loan Agreement as of March 31, 2015 are as follows (in thousands):
	Years Ending December 31,
	2015	$	551
	2016		6,822
	2017		8,786
	2018		4,450
	Total future minimum payments	$	20,609
	Less: amount representing unamortized interest		(1,528	)
	Less: amount representing debt discount		(889	)
	Total minimum payments	$	18,192
	Less: current portion		(1,529	)
	Non-current portion	$	16,663

Equity_Incentive_Plan_and_Stoc1

Equity Incentive Plan and Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based 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,
		2015		2014
	Cost of sales	$	24	$	2
	Research and development		493		147
	Selling general and administrative		1,915		1,219
	Total	$	2,432	$	1,368

Net_Income_per_Share_of_Common1

Net Income per Share of Common Stock (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Net Income Per Share of Common Stock	The following table sets forth the computation of basic and diluted net income per share of common stock for the periods indicated (in thousands, except share and per share amounts):
		Three Months Ended
		March 31,
		2015		2014
	Net income per share
	Numerator:
	Net income attributable to common stockholders	$	7,216	$	1,259
	Denominator:
	Weighted-average number of common shares outstanding – basic		20,780,059		20,191,190
	Dilutive effect of stock-options and awards		1,299,401		1,327,336
	Weighted average common shares outstanding – dilutive		22,079,460		21,518,526
	Net income per share:
	Basic	$	0.35	$	0.06
	Diluted	$	0.33	$	0.06
Antidilutive Securities Excluded from Computation of Earnings Per Share	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income per share, as the effect of including them would have been antidilutive:
		Three Months Ended
		March 31,
		2015		2014
	Stock options		1,443,122		1,181,650
	October 2007 common stock warrants		274		274
	Total		1,443,396		1,181,924

Segment_Reporting_Tables

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Net Product Revenue for Ravicti and Buphenyl	Net product revenue for RAVICTI and BUPHENYL for the three months ended March 31, 2015 and 2014 are as follows (in thousands):
		Three Months Ended
		March 31,
		2015		2014
	RAVICTI	$	25,966	$	15,516
	BUPHENYL		5,227		3,967
	Total	$	31,193	$	19,483
Net Product Revenue for Ravicti and Buphenyl by Geographic Region	Net product revenue for RAVICTI and BUPHENYL by geographic region are as follows (in thousands):
		Three Months Ended
		March 31,
		2015		2014
	United States	$	28,212	$	17,996
	Canada		1,147		800
	Rest of the world		1,834		687
	Total	$	31,193	$	19,483

Formation_and_Business_of_the_1

Formation and Business of the Company - Additional Information (Detail) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Mar. 13, 2013	Mar. 29, 2015	Dec. 31, 2014	Aug. 14, 2013
Nature Of Operations [Line Items]
Entity incorporation, date	1-Nov-06
Entity incorporation, state name	Delaware
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
Sales of securities	0
Accumulated deficit	-121,409,000			-128,625,000
Common stock, price per share			$46
Merger agreement description	The Completion of the Offer is subject to several conditions, including (i) there shall have been validly tendered and not validly withdrawn Shares that represent one more than 50% of the sum of (A) the total number of Shares outstanding at the time of the expiration of the Offer plus (B) the aggregate number of Shares issuable to holders of stock options of the Company and warrants to purchase shares of common stock of the Company from which the Company has received notices of exercise prior to the consummation of the Offer (and as to which Shares have not yet been issued to such exercising holders of the Companybs Options); (ii) the expiration or termination of any applicable waiting period relating to the Offer under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended; (iii) the absence of a material adverse effect on the Company; (iv) subject to certain materiality exceptions, the truth and accuracy of certain representations and warranties of the Company contained in the Merger Agreement; (v) Horizonbs receipt of debt financing pursuant to the debt commitment letter (or any alternative financing) or Horizonbs receipt of confirmation from its lenders the debt financing (or an alternative financing) will be available at the consummation of the Offer; and (vi) certain other customary conditions. The offer will expire at 12:01 A.M. on May 7, 2015.
Merger agreement date	29-Mar-15
Offer expiry date	7-May-15
Follow-on offering
Nature Of Operations [Line Items]
Net proceeds from public offering		63,700,000
Underwriting discounts and commissions		4,100,000
Other offering expenses		$800,000

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Allowances for doubtful accounts	$0
Adjustments to accrued preclinical trail expenses	0
Percentage of Medicare Part D insurance coverage gap to eligible patients	50.00%
Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Credit losses on investments	$0
United States | Credit Concentration Risk | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration risk by specialty distributor	94.00%	87.00%
United States | Credit Concentration Risk | Sales Revenue, Net [Member] | Other Distributor
Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration risk by specialty distributor	10.00%		10.00%
United States | Credit Concentration Risk | Sales Revenue, Net [Member] | Specialty Distributor
Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration risk by specialty distributor	90.00%		92.00%
International | Credit Concentration Risk | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration risk by specialty distributor	10.00%	10.00%

Collaboration_Agreement_with_U1

Collaboration Agreement with Ucyclyd Pharma, Inc. - Additional Information (Detail) (Purchase agreement with Ucyclyd, RAVICTI, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2012
Scenario One
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Maximum amount of regulatory milestones, product approval		$15.80
Regulatory milestones, product approval, description	Regulatory milestones related to approval of GPB in HE
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
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		$38.80

Completion_of_Phase_3_Clinical1

Completion of Phase 3 Clinical Trial, Option and Mutual Release Agreement - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Other Commitments [Line Items]
Fair value of common stock classified as deferred gain	$2,595,000
Common stock
Other Commitments [Line Items]
Number of trading days for valuation of shares	15 days
Andromeda
Other Commitments [Line Items]
Estimated budget for trial	10,500,000
Increase in estimated budget for trial	2,250,000
Option to acquire outstanding stock payable	3,500,000
Consideration receivable in shares of common stock	400,000
Andromeda | Maximum
Other Commitments [Line Items]
Contingent payments based on future revenue	36,500,000
Andromeda | Common stock
Other Commitments [Line Items]
Consideration paid in shares of common stock	$2,500,000

Schedule_of_Investments_by_Con

Schedule of Investments by Contractual Maturity (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Contractual Maturity Year One	$39,756	$34,512
Contractual Maturity Year Two	25,035	9,251
Contractual Maturity, Total Book Value	64,791	43,763
Unrealized Loss	-35	-50
Aggregate Fair Value	64,756	43,713
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Contractual Maturity Year One	7,700	12,613
Contractual Maturity Year Two	18,075	3,011
Contractual Maturity, Total Book Value	25,775	15,624
Unrealized Loss	-26	-12
Aggregate Fair Value	25,749	15,612
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Contractual Maturity Year One	24,645	18,405
Contractual Maturity Year Two	6,960	6,240
Contractual Maturity, Total Book Value	31,605	24,645
Unrealized Loss	-7	-35
Aggregate Fair Value	31,598	24,610
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Contractual Maturity Year One	3,496	3,494
Contractual Maturity, Total Book Value	3,496	3,494
Unrealized Loss	-1	-3
Aggregate Fair Value	3,495	3,491
U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Contractual Maturity Year One	3,915
Contractual Maturity, Total Book Value	3,915
Unrealized Loss	-1
Aggregate Fair Value	$3,914

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
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, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months to Maturity, Aggregate Fair Value	$39,742	$34,487
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	-14	-24
12 Months or More to Maturity, Aggregate Fair Value	25,014	9,226
12 Months or More to Maturity, Unrealized Loss	-21	-26
Aggregate Fair Value, Total	64,756	43,713
Unrealized Gain (Loss), Total	-35	-50
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months to Maturity, Aggregate Fair Value	7,697	12,610
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	-3	-2
12 Months or More to Maturity, Aggregate Fair Value	18,052	3,002
12 Months or More to Maturity, Unrealized Loss	-23	-10
Aggregate Fair Value, Total	25,749	15,612
Unrealized Gain (Loss), Total	-26	-12
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months to Maturity, Aggregate Fair Value	24,636	18,386
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	-9	-19
12 Months or More to Maturity, Aggregate Fair Value	6,962	6,224
12 Months or More to Maturity, Unrealized Loss	2	-16
Aggregate Fair Value, Total	31,598	24,610
Unrealized Gain (Loss), Total	-7	-35
U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months to Maturity, Aggregate Fair Value	3,914
Less Than 12 Months to Maturity, Unrealized Gain (Loss)	-1
Aggregate Fair Value, Total	3,914
Unrealized Gain (Loss), Total	-1
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	-3
Aggregate Fair Value, Total	3,495	3,491
Unrealized Gain (Loss), Total	($1)	($3)

Hierarchy_for_Assets_and_Liabi

Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	$38,286	$39,252
Fair value of available-for-sale securities	64,756	43,713
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents		720
Fair value of available-for-sale securities	31,598	24,610
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
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	3,914
Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of available-for-sale securities	25,749	15,612
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	39,742	34,487
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	24,636	18,386
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 | 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	3,914
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	7,697	12,610
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	25,014	9,226
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	6,962	6,224
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	18,052	3,002
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	38,286	38,532
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	38,286	38,532
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	38,286	38,532
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents		720
Fair value of available-for-sale securities	64,756	43,713
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		720
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	39,742	34,487
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	24,636	18,386
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 | 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	3,914
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	7,697	12,610
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	25,014	9,226
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	6,962	6,224
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	$18,052	$3,002

Carrying_Value_and_Estimated_F

Carrying Value and Estimated Fair Value of Company's Notes Payable and Term Loans (Detail) (Term Loans, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	$16,192	$16,124
Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	$16,759	$16,746

Components_of_Inventories_Deta

Components of Inventories (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]
Raw Materials	$2,556	$1,787
Work-in-process	867	543
Finished goods	2,174	2,291
Total	$5,597	$4,621

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]
Inventory reserves	$0.30	$0.30

Intangible_Asset_Additional_In

Intangible Asset - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	31-May-13
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible asset	$893,000	$1,014,000
BUPHENYL
Finite-Lived Intangible Assets [Line Items]
Intangible asset acquired			$16,500,000
Estimated useful life of intangible assets	10 years
Remaining average useful life	7 years 9 months 18 days

Schedule_of_Expected_Amortizat

Schedule of Expected Amortization Expense (Detail) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]
2015	$3,571
2016	975
2017	893
2018	871
2019	$849

Components_of_Property_and_Equ

Components of Property and Equipment (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$1,829	$1,756
Less: Accumulated depreciation	-758	-640
Total property and equipment, net	1,071	1,116
Computers and Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,423	1,202
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	$33	$181

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Property, Plant and Equipment [Abstract]
Depreciation expense	$0.10	$0.10

Components_of_Accrued_Liabilit

Components of Accrued Liabilities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Clinical and clinical trial expenses	$1,247	$2,399
Payroll and related expenses	2,917	4,134
Gross to net sales accruals	13,197	10,142
Royalty payable	2,067	2,080
Legal accrual	994	410
Taxes payable	921	563
Acquisition related accrual (see below)		4,615
Other (Note 4)	5,271	1,166
Total	$26,614	$25,509

Accrued_Liabilities_Additional

Accrued Liabilities - Additional Information (Detail) (Andromeda, USD $)	0 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Feb. 16, 2015	Mar. 31, 2015	Dec. 31, 2014
Andromeda
Schedule of Accrued Liabilities [Line Items]
Milestone payment exchange	$0.50
Accrued liabilities			4.6
Other income		$4.10

Notes_Payable_Additional_Infor

Notes Payable - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Jul. 18, 2014	Mar. 31, 2015	Mar. 31, 2014
Silicon Valley Bank
Debt Instrument [Line Items]
Pre-payment of term loans	$5.80
Repayment of loans, description		The Company is required to pay interest only for the first 18 months of the Term Loans, followed by 30 equal monthly payments of interest and principal.
Interest rate on loans, description		The Loan Agreement provides for an interest rate of 4.0% per year on the Term Loans and the prime rate plus 0.75% per year on the Revolving Loans, with a minimum interest requirement on the Revolving Loans.
Final payment due as a percentage of principal loan amount		6.75%
Period for monthly financials and compliance certificate		30 days
Period for quarterly financial statements		45 days
Period for annual audited financial report		180 days
Percentage Of Financial Instruments		75.00%
Value Of Financial Instruments		40
Debt Instrument, Covenant Description		At least the lesser of (i) seventy five percent (75%) of the dollar value of the Company and its Subsidiaries' accounts at all financial institutions or (ii) $40.0 million; provided, however, that the Company's obligation relating to foreign exchange transactions is subject to SVB providing commercially competitive exchange rates.
Silicon Valley Bank | Term Loans
Debt Instrument [Line Items]
Number of tranches	2
Loan and security agreement, maximum borrowings	16
Term loans maturity date		30-Jun-18
Silicon Valley Bank | Revolving Loans
Debt Instrument [Line Items]
Loan and security agreement, maximum borrowings	5
Drew down from revolving line of credit facility	2
Term loans maturity date		18-Jul-17
April 2012 and September 2012 Notes Payable and Term Loans
Debt Instrument [Line Items]
Amortization of debt discount		$0.10	$0.10

Future_Minimum_Payments_Under_

Future Minimum Payments Under Loan Agreement (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Less: current portion	($1,529)
Non-current portion	16,663	18,124
Loan Agreement
Debt Instrument [Line Items]
2015	551
2016	6,822
2017	8,786
2018	4,450
Total future minimum payments	20,609
Less: amount representing unamortized interest	-1,528
Less: amount representing debt discount	-889
Total minimum payments	18,192
Less: current portion	-1,529
Non-current portion	16,663
Total minimum payments	$18,192

Warrants_Additional_Informatio

Warrants - Additional Information (Detail) (October 2007 Common Stock Warrants, USD $)	3 Months Ended
	Mar. 31, 2015	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	Oct-17

Equity_Incentive_Plan_and_Stoc2

Equity Incentive Plan and Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Inventories
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation capitalized into inventories	$47,000	$8,000
2012 Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Shares available for issuance under plan	994,222
Share options outstanding under plan	1,903,719
Options granted during period	246,700
Option exercise price, minimum	$24.94
Option exercise price, maximum	$25.97
Increase in shares approved for issuance under plan	829,880
2012 Plan | Restricted stock units ("RSU's")
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock units outstanding under plan	388,130
Stock units, Granted	289,127
2012 Plan | Performance stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock units outstanding under plan	8,662
Stock units, Granted	8,662
2006 Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share options outstanding under plan	1,204,359

Allocation_of_StockBased_Compe

Allocation of Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses related to employees	$2,432	$1,368
Cost of sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses related to employees	24	2
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses related to employees	493	147
Selling general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses related to employees	$1,915	$1,219

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Tax Credit Carryforward [Line Items]
Income tax expense	$1,555,000	$88,000
Interest or penalties accrued	0
United States
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards			36,400,000
Operating loss expirations	Begin to expire in 2031
United States | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	22,600,000
California
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards			107,800,000
Operating loss expirations	Begin to expire in 2028
Israel Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards			67,300,000
Operating loss expirations	Do not expire
Federal Orphan Drug Credit | United States | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$21,100,000

Recovered_Sheet1

Net Income Per Share of Common Stock (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net income per share Numerator:
Net income attributable to common stockholders	$7,216	$1,259
Denominator:
Weighted-average number of common shares outstanding - basic	20,780,059	20,191,190
Dilutive effect of stock-options and awards	1,299,401	1,327,336
Weighted average common shares outstanding - dilutive	22,079,460	21,518,526
Net income per share:
Basic	$0.35	$0.06
Diluted	$0.33	$0.06

Antidilutive_Securities_Exclud

Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the computation of diluted net loss per share	1,443,396	1,181,924
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	1,443,122	1,181,650
October 2007 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	274

RelatedParty_Transaction_Addit

Related-Party Transaction - Additional Information (Detail) (Swedish Orphan Biovitrum AB, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Swedish Orphan Biovitrum AB
Related Party Transaction [Line Items]
Sales recognized	$1.60
Accounts receivable from SOBI	$0.60

Net_Product_Revenue_for_Ravict

Net Product Revenue for Ravicti and Buphenyl (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenue from External Customer [Line Items]
Revenue	$31,193	$19,483
RAVICTI
Revenue from External Customer [Line Items]
Revenue	25,966	15,516
BUPHENYL
Revenue from External Customer [Line Items]
Revenue	$5,227	$3,967

Net_Product_Revenue_for_Ravict1

Net Product Revenue for Ravicti and Buphenyl by Geographic Region (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Revenue	$31,193	$19,483
United States
Segment Reporting Information [Line Items]
Revenue	28,212	17,996
Canada
Segment Reporting Information [Line Items]
Revenue	1,147	800
Rest of the world
Segment Reporting Information [Line Items]
Revenue	$1,834	$687