Hyperion Therapeutics (HPTX) 10-K 7 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 28, 2014	Jun. 28, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'HPTX	'	'
Entity Registrant Name	'HYPERION THERAPEUTICS INC	'	'
Entity Central Index Key	'0001386858	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	20,179,819	'
Entity Public Float	'	'	$213,779,808

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$74,232	$49,853
Short-term investments	28,045	'
Accounts receivable, net	4,419	'
Inventories	3,513	'
Prepaid expenses and other current assets	1,403	1,155
Total current assets	111,612	51,008
Long-term investments	15,780	'
Property and equipment, net	936	49
Intangible asset, net	13,442	'
Other non-current assets	749	147
Total assets	142,519	51,204
Current liabilities	'	'
Accounts payable	2,292	2,177
Accrued liabilities	12,187	2,540
Notes payable, current portion	5,652	4,348
Total current liabilities	20,131	9,065
Notes payable, net of current portion	2,621	7,750
Deferred rent	81	'
Total liabilities	22,833	16,815
Commitments and contingencies (Note 13)	'	'
Stockholders' equity	'	'
Preferred stock, par value $0.0001 - 10,000,000 shares authorized at December 31, 2013 and 2012; none issued and outstanding	'	'
Common stock, par value $0.0001 - 100,000,000 shares authorized at December 31, 2013 and 2012; 20,137,145 and 16,646,269 shares issued and outstanding at December 31, 2013 and 2012, respectively	2	2
Additional paid-in capital	242,109	173,384
Accumulated other comprehensive loss	-55	'
Accumulated deficit	-122,370	-138,997
Total stockholders' equity	119,686	34,389
Total liabilities and stockholders' equity	$142,519	$51,204

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]	'	'
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	20,137,145	16,646,269
Common stock, shares outstanding	20,137,145	16,646,269

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]	'	'	'
Net product revenue	$42,204	'	'
Costs and expenses:	'	'	'
Cost of sales	6,740	'	'
Research and development	9,984	17,046	17,236
Selling, general and administrative	35,839	11,487	8,923
Amortization of intangible asset	3,058	'	'
Total costs and expenses	55,621	28,533	26,159
Loss from operations	-13,417	-28,533	-26,159
Interest income	27	12	28
Interest expense	-1,539	-3,703	-2,554
Gain from settlement of retention option (Note 4)	31,079	'	'
Other income (expense), net	526	-39	-731
Income (loss) before income taxes	16,676	-32,263	-29,416
Income tax expense	49	'	'
Net income (loss)	$16,627	($32,263)	($29,416)
Net income (loss) per share:	'	'	'
Basic	$0.86	($4.45)	($62.68)
Diluted	$0.80	($4.45)	($62.68)
Weighted average number of shares used to compute net income (loss) per share of common stock:	'	'	'
Basic	19,415,822	7,256,537	469,319
Diluted	20,730,913	7,256,537	469,319

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Loss) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net income (loss)	$16,627	($32,263)	($29,416)
Other comprehensive loss:	'	'	'
Unrealized loss on investments arising during the year	-55	'	'
Other comprehensive loss	-55	'	'
Comprehensive income (loss)	$16,572	($32,263)	($29,416)

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (Deficit) (USD $)

Total

Convertible Notes Payable

Initial Public Offering

Convertible preferred stock

Common Stock

Common Stock

Common Stock

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Accumulated Other Comprehensive Loss

Accumulated Deficit

In Thousands, except Share data

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Convertible Notes Payable

Initial Public Offering

USD ($)

Convertible Notes Payable

Initial Public Offering

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Balance at Dec. 31, 2010

($54,176)

'

'

$58,326

'

'

'

$23,142

'

'

'

($77,318)

Balance, shares at Dec. 31, 2010

'

'

'

6,575,637

469,319

'

'

'

'

'

'

'

Stock-based compensation expense

345

'

'

'

'

'

'

345

'

'

'

'

Gain on extinguishment of debt

1,143

'

'

'

'

'

'

1,143

'

'

'

'

Net income (loss)

-29,416

'

'

'

'

'

'

'

'

'

'

-29,416

Balance at Dec. 31, 2011

-82,104

'

'

58,326

'

'

'

24,630

'

'

'

-106,734

Balance, shares at Dec. 31, 2011

'

'

'

6,575,637

469,319

'

'

'

'

'

'

'

Issuance of stock

'

'

51,312

'

'

'

1

'

'

51,311

'

'

Issuance of common stock upon conversion of convertible securities

58,326

'

'

-58,326

1

'

'

58,325

'

'

'

'

Issuance of stock (in shares)

'

'

'

'

'

'

5,750,000

'

'

'

'

'

Issuance of common stock upon conversion of convertible securities (in shares)

'

'

'

-6,575,637

6,575,637

'

'

'

'

'

'

'

Conversion of convertible notes payable and accrued interest to common stock

33,322

33,322

'

'

'

'

'

'

33,322

'

'

'

Conversion of convertible notes payable and accrued interest to common stock, (in shares)

'

'

'

'

'

3,444,870

'

'

'

'

'

'

Issuance of common stock upon automatic net exercise of warrants

3,901

'

'

'

'

'

'

3,901

'

'

'

'

Issuance of common stock upon automatic net exercise of warrants (in shares)

'

'

'

'

340,361

'

'

'

'

'

'

'

Issuance of common stock warrant

755

'

'

'

'

'

'

755

'

'

'

'

Issuance of common stock upon exercise of stock options

147

'

'

'

'

'

'

147

'

'

'

'

Issuance of common stock upon exercise of stock options (in shares)

'

'

'

'

66,082

'

'

'

'

'

'

'

Stock-based compensation expense

993

'

'

'

'

'

'

993

'

'

'

'

Net income (loss)

-32,263

'

'

'

'

'

'

'

'

'

'

-32,263

Balance at Dec. 31, 2012

34,389

'

'

'

2

'

'

173,384

'

'

'

-138,997

Balance, shares at Dec. 31, 2012

'

'

'

'

16,646,269

'

'

'

'

'

'

'

Issuance of stock

'

'

63,712

'

'

'

'

'

'

63,712

'

'

Issuance of stock (in shares)

'

'

'

'

'

'

3,306,250

'

'

'

'

'

Exercise of common stock warrants (in shares)

'

'

'

'

'

67,503

'

'

'

'

'

'

Issuance of common stock upon exercise of stock options

637

'

'

'

'

'

'

637

'

'

'

'

Issuance of common stock upon exercise of stock options (in shares)

'

'

'

'

117,123

'

'

'

'

'

'

'

Stock-based compensation expense

4,376

'

'

'

'

'

'

4,376

'

'

'

'

Other comprehensive loss

-55

'

'

'

'

'

'

'

'

'

-55

'

Net income (loss)

16,627

'

'

'

'

'

'

'

'

'

'

16,627

Balance at Dec. 31, 2013

$119,686

'

'

'

$2

'

'

$242,109

'

'

($55)

($122,370)

Balance, shares at Dec. 31, 2013

'

'

'

'

20,137,145

'

'

'

'

'

'

'

Consolidated_Statements_of_Sto1

Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Statement Of Stockholders Equity [Abstract]	'	'
Underwriting discounts and commissions	$4,116	$4,025
Offering costs	$776	$2,163

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities	'	'	'
Net income (loss)	$16,627	($32,263)	($29,416)
Adjustments to reconcile net income (loss) to net cash used in operating activities	'	'	'
Depreciation and amortization	198	15	69
Amortization of debt discount and debt issuance costs	556	1,381	1,562
Re-measurement of warrants liability	'	780	1,072
Re-measurement of call option liability and preferred stock liability	'	-737	-351
Stock-based compensation expense	4,294	993	345
Amortization of intangible asset	3,058	'	'
Gain from settlement of retention option (Note 4)	-31,079	'	'
Unrealized loss on foreign currency translation adjustments	14	'	'
Amortization of discount on available-for-sale investments	51	'	'
Changes in assets and liabilities	'	'	'
Accounts receivable	-4,433	'	'
Inventories, net of acquisition	468	'	'
Prepaid expenses and other assets	-809	-249	-387
Accounts payable	115	290	1,203
Accrued liabilities	9,647	1,259	1,372
Deferred rent	81	'	'
Net cash used in operating activities	-1,212	-28,531	-24,531
Cash flows from investing activities	'	'	'
Acquisition of property and equipment	-1,085	-45	-8
Purchase of available-for-sale investments	-43,931	'	'
Option to purchase BUPHENYL and AMMONUL (Note 4)	'	-283	'
Acquisition of rights to BUPHENYL, net of AMMONUL option (Note 4)	10,962	'	'
Change in restricted cash	'	330	-4
Net cash provided by (used in) investing activities	-34,054	2	-12
Cash flows from financing activities	'	'	'
Proceeds from issuance of common stock in initial public offering, net of underwriting discounts	'	53,475	'
Proceeds from issuance of common stock in follow-on offering, net of underwriting discounts	64,488	'	'
Proceeds from issuance of common stock from stock option exercises	637	147	'
Proceeds from issuance of convertible notes payable	'	7,504	24,982
Proceeds from issuance of notes payable, net of issuance costs	'	12,401	'
Payments of offering costs	-1,132	-2,163	'
Principal payments under notes payable	-4,348	'	'
Net cash provided by financing activities	59,645	71,364	24,982
Net increase in cash and cash equivalents	24,379	42,835	439
Cash and cash equivalents, beginning of period	49,853	7,018	6,579
Cash and cash equivalents, end of period	74,232	49,853	7,018
Supplemental cash flow information	'	'	'
Cash paid for interest	966	593	'
Supplemental disclosure of noncash investing and financing activities	'	'	'
Warrants issued in connection with notes payable	'	1,302	1,502
Issuance of call option related to convertible notes payable	'	'	1,707
Gain on extinguishment of debt	'	'	1,143
Stock-based compensation capitalized into inventories	82	'	'
Option to purchase rights to BUPHENYL and AMMONUL (Note 4)	283	'	'
Issuance of common stock upon automatic net exercise of warrants	'	3,901	'
Conversion of convertible notes payable and accrued interest to common stock	'	33,322	'
Conversion of Series C-1 and C-2 preferred stock to common stock	'	$58,326	'

Formation_and_Business_of_the_

Formation and Business of the Company	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Formation and Business of the Company	'
	1	Formation and Business of the Company
	Hyperion Therapeutics, Inc. (the “Company”) was incorporated in the state of Delaware on November 1, 2006. The Company was in the development stage from inception through March 31, 2013. During this period, the Company’s activities consisted primarily of raising capital, negotiating a promotion and drug development collaboration agreement, establishing a management team and performing drug development activities. The Company launched RAVICTI® (glycerol phenylbutyrate) Oral Liquid during the quarter ended March 31, 2013 and acquired BUPHENYL® (sodium phenylbutyrate) Tablets and Powder in May 2013. During the quarter ended June 30, 2013, the Company had significant revenues from principal operations and therefore, ceased being a development stage company.
	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 and hepatology. The Company has developed RAVICTI to treat the most prevalent urea cycle disorders (“UCD”) and is developing glycerol phenylbutyrate (“GPB”) for the potential treatment of hepatic encephalopathy (“HE”). UCD and HE are generally characterized by elevated levels of ammonia in the bloodstream. Elevated levels of ammonia are potentially toxic and can lead to severe medical complications which may include death. The Company’s product, RAVICTI, is designed to lower ammonia in the blood. UCD are inherited rare genetic diseases caused by a deficiency of one or more enzymes or transporters that constitute the urea cycle, which in a healthy individual removes ammonia through conversion of ammonia to urea. HE is a serious but potentially reversible neurological disorder that can occur in patients with liver scarring, known as cirrhosis, or acute liver failure. On February 1, 2013, the U.S. Food and Drug Administration (“FDA”), granted approval of RAVICTI for the use as a nitrogen-binding agent for chronic management of adult and pediatric UCD patients greater than two years of age who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. On May 31, 2013, the Company acquired BUPHENYL, an FDA-approved therapy for treatment of the most prevalent UCD, from Ucyclyd Pharma Inc. (“Ucyclyd”), a subsidiary of Valeant Pharmaceuticals International, Inc. (“Valeant”). Subsequent to the acquisition on May 31, 2013, the Company started selling BUPHENYL Tablets and Powder within and outside the United States.
	Hyperion Therapeutics Limited was formed in January 2008 as a private limited company under the Companies Act 1985 for England and Wales and is wholly owned by the Company. Since its incorporation, there has been no activity in Hyperion Therapeutics Limited.
	On July 31, 2012, the Company completed its initial public offering (“IPO”) and issued 5,000,000 shares of its common stock at an initial offering price of $10.00 per share. In addition, the Company sold an additional 750,000 shares of common stock directly to its underwriters when they exercised their over-allotment option in full at the initial offering price of $10.00 per share. The shares began trading on the NASDAQ Global Market on July 26, 2012. The Company received net proceeds from the IPO of $51.3 million, after deducting underwriting discounts and commissions of $4.0 million and expenses of $2.2 million. Upon the closing of the IPO, the Company’s Series C-1 and Series C-2 preferred stock converted into 1,912,598 and 4,663,039 shares of common stock, respectively. In addition, the principal and accrued interest under the Company’s April 2011 Notes and October 2011 Notes amounting to $18.9 million and $15.6 million, respectively, converted into 1,888,054 and 1,556,816 shares of common stock. As of July 31, 2012, the carrying value of the April 2011 Notes including the impact of the amendment to the April 2011 Notes as discussed in and accrued interest under the April 2011 Notes was $18.4 million. As of July 31, 2012, the carrying value (net of discount) and accrued interest under the October 2011 Notes was $14.9 million. Additionally, the April 2011 common stock warrants and October 2011 preferred stock warrants were converted into 322,599 and 17,762 shares of common stock, respectively, immediately prior to the closing of the IPO.
	On March 13, 2013, the Company completed its follow-on offering and issued 2,875,000 shares of its common stock at an offering price of $20.75 per share. In addition, the Company sold an additional 431,250 shares of common stock directly to its underwriters when they exercised their over-allotment option in full at the offering price of $20.75 per share. 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 December 31, 2013, there were no sales of any securities registered pursuant to the shelf registration statement.
	Since inception, the Company has incurred recurring annual net operating losses and negative cash flows from operations. During the year ended December 31, 2013, the Company incurred a loss from operations of $13.4 million and used $1.2 million of cash in operations. At December 31, 2013, the Company had an accumulated deficit of $122.4 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 for RAVICTI and BUPHENYL in UCD. Management’s plans with respect to these matters include utilizing a substantial portion of the Company’s capital resources and efforts in completing the development and obtaining regulatory approval of GPB in HE, expanding the Company’s organization, and commercialization of RAVICTI and marketing of BUPHENYL.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	2	Summary of Significant Accounting Policies
	Basis of Presentation and the Use of Estimates
	The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of the accompanying 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 consolidated 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 the 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.
	Basis of Consolidation
	The consolidated financial statements include the accounts of the Company and Hyperion Therapeutics Limited. All intercompany balances and transactions, if any, have been eliminated for purposes of consolidation.
	Reclassifications
	Certain prior year amounts in the consolidated financial statements have been reclassified to conform to the current year’s presentation. In particular, sales and marketing expenses have been combined with general and administrative expenses in the consolidated statements of operations. The result of this reclassification had no impact on the previously reported net loss, the consolidated balance sheets or the consolidated statements of cash flows.
	Segment Reporting
	The Company operates as one operating segment and uses one measurement of profitability to manage its business. All long-lived assets are maintained in the United States. For the year ended December 31, 2013, net product revenue in the United States and rest of the world (primarily Canada and Europe) was $37.0 million and $5.2 million, respectively. For the year ended December 31, 2013, net product revenue consisted of net sales from RAVICTI of $31.2 million and net sales from BUPHENYL of $11.5 million partially offset by $0.5 million of co-payment assistance.
	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 December 31, 2013, 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 consist of raw materials and finished goods. Costs 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 consolidated statements of operations. If information becomes available that suggest that inventories may not be realizable, the Company may be required to expense a portion or all of the previously capitalized inventories.
	Products that have been approved by the FDA or other regulatory authorities, such as RAVICTI are also used in clinical programs, to assess the safety and efficacy of the products for usage in diseases that have not been approved by the FDA or other regulatory authorities. The form of RAVICTI utilized for both commercial and clinical programs is identical and, as a result, the inventory has an “alternative future use” as defined in authoritative guidance. Raw materials and purchased drug product associated with clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes and, therefore, does not have an “alternative future use”.
	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd (see Note 4). The Company recorded the acquired BUPHENYL inventories at fair value in the amount of $3.9 million on the acquisition date. The Company is expensing the difference between the fair value and book value of inventory as that inventory is sold.
	Business Combinations
	The Company allocates the purchase price of an acquired business to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. Any excess of the purchase price over the fair value of the net assets acquired is recorded as goodwill. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets. Direct transaction costs associated with the business combination are expensed as incurred.
	Intangible Assets
	Intangible assets are recorded at acquisition cost less accumulated amortization and impairment. Intangible assets with finite lives are amortized over their estimated useful lives. The Company’s intangible asset pertains to BUPHENYL product rights (see Note 4). The intangible asset is amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefits of the intangible asset are consumed as revenue is generated. The pattern of consumption of the economic benefits is estimated using the future projected cash flows of the intangible asset.
	Impairment of Long-lived Assets
	The Company reviews its property and equipment, intangible assets subject to amortization and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset group 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.
	Property and Equipment
	Property and equipment are stated at cost, net of accumulated depreciation and amortization. All property and equipment is depreciated on a straight-line basis over the following estimated useful lives:
	Computer and office equipment		3 – 5 years
	Software		3 years
	Furniture and fixtures		3 years
	Leasehold improvements are amortized over the lesser of their useful life or the term of the applicable lease. Upon sale or retirement of assets, the cost and related accumulated depreciation and amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in operations. Maintenance and repairs are charged to operations as incurred.
	2012 Reverse Stock Split
	The Company effected a 1-for-6.09 reverse stock split of its common stock and preferred stock on July 12, 2012. Accordingly, all share and per share amounts for all periods presented in these consolidated financial statements and notes thereto, have been adjusted retroactively to reflect this reverse stock split.
	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. In 2013 there were no credit losses on the Company’s accounts receivable. As at December 31, 2013, the specialty distributor in the United States accounted for 64% of the accounts receivable balance and one international distributor accounted for 17% of the accounts receivable balance.
	Fair Value of Financial Instruments
	The Company measures certain financial assets and liabilities at fair value based on the exchange price that would be received for an asset or paid for to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. The carrying amounts of the Company’s financial instruments, including cash equivalents, short-term investments, the option to purchase BUPHENYL and AMMONUL, accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of long-term investments represent their estimated fair values. The Company’s debt obligations are carried at historical cost, which approximates fair value.
	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.
	Warrants Liability
	The Company accounts for its warrants and other derivative financial instruments as either equity or liabilities based upon the characteristics and provisions of each instrument. Warrants classified as equity are recorded as additional paid-in capital on the consolidated balance sheets and no further adjustments to their valuation are made. Warrants classified as derivative liabilities and other derivative financial instruments that require separate accounting as liabilities are recorded on the Company’s consolidated balance sheets at their fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized as increases or reductions to other income (expense), net in the consolidated statements of operations.
	Revenue Recognition
	The Company recognizes revenue in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, Revenue Recognition, when the following criteria have been met: persuasive evidence of an arrangement exists; delivery has occurred and risk of loss has passed; the seller’s price to the buyer is fixed or determinable and collectability is reasonably assured. The Company determines that persuasive evidence of an arrangement exists based on written contracts that defined the terms of the arrangements. In addition, the Company determines that services have been delivered in accordance with the arrangement. The Company assesses whether the fee is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. The Company assesses collectability based primarily on the customer’s payment history and on the creditworthiness of the customer.
	Product Revenue, net: The Company’s product revenue represents sales of RAVICTI and BUPHENYL which are recognized once all four revenue recognition criteria described above are met. The Company recognizes revenue net of product sales allowances. Product shipping and handling costs are included in cost of sales.
		•	During 2013, the Company began distributing RAVICTI to two specialty pharmacies through a specialty distributor. The specialty pharmacies then in turn dispensed RAVICTI to patients in fulfillment of prescriptions. As RAVICTI is a new product, and the Company’s first commercial product, the Company could not reasonably assess potential product sales allowances at the time of sale to the specialty distributor. As a result, the price of RAVICTI was not deemed fixed or determinable. The Company does not record revenue on shipments of RAVICTI to the specialty distributor, until the product was shipped to patients by the specialty pharmacies at which time the related product sales allowances could be reasonably estimated.
		•	As discussed in Note 4, on May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. The Company sells BUPHENYL in the United States to a specialty distributor who in turn sells this product to retail pharmacies, hospitals and other dispensing organizations. The Company records revenue on product shipments to the specialty distributor upon receipt by the specialty distributor. For product sales of BUPHENYL outside the United States, revenue is recognized once the product is accepted by the customer or their acceptance period has expired, whichever comes first.
	Product Sales Allowances: The Company establishes reserves for prompt-payment discounts, government and commercial rebates, product returns and chargebacks. Allowances related to prompt-payment discounts 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 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 distributor, two specialty pharmacies and our dedicated call center. 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 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 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 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 consolidated balance sheet.
	Co-payment assistance: The Company provides a cash donation to a non-profit third party organization which supports UCD 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. Cost of BUPHENYL sales as a percentage of revenue was higher and not indicative of cost of sales in future periods due to the recording of the step-up value on BUPHENYL inventories acquired from Ucyclyd which is expensed to cost of sales as that inventory is sold. (See Note 4)
	Foreign Currency Translations
	The Company has cash and accounts receivable denominated in foreign currency are translated at the rate of exchange in effect on the balance sheet date. Revenue and expenses denominated in foreign currency are translated at the weighted average rate of exchange prevailing during the period. Any gains and losses resulting from foreign currency translations are included in other income (expense)-net in the consolidated statements of operations.
	Research and Development Expenses
	Costs related to research and development of products are charged to expense as incurred. Research and development costs include, but are not limited to, payroll and personnel expenses, clinical trial supplies, fees for clinical trial services, consulting costs and allocated overhead, including rent, equipment, depreciation and utilities.
	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.
Comprehensive Income (Loss)
Comprehensive income (loss) is comprised of net income (loss) and other comprehensive loss. Other comprehensive loss includes changes in stockholders’ equity that are excluded from net income (loss), specifically changes in unrealized gains and losses on the Company’s available-for-sale securities.
Net Income (Loss) per Share of Common Stock
Basic earnings per share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the periods presented. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and other potentially dilutive securities using the treasury stock method, unless the effect is antidilutive.
Recent Accounting Pronouncements
In February 2013, FASB issued Accounting Standard Update (“ASU”) No. 2013-02, Comprehensive Income: Reporting of amounts reclassified out of other comprehensive income. Under the amendments of this update an entity is required to present either parenthetically on the face of the financial statements or in the notes, significant amounts reclassified from each component of accumulated other comprehensive income and the income statement line items affected by the reclassification. However, an entity would not need to show the income statement line item affected for certain components that are not required to be reclassified in their entirety to net income, such as amounts amortized into net periodic pension cost. The standard was effective prospectively for public entities for fiscal years, and interim periods with those years, beginning after December 15, 2012. Early adoption was permitted. The Company adopted this guidance on January 1, 2013. The implementation did not have an impact on the Company’s consolidated financial statements.
In July 2013, FASB issued ASU No. 2013-11, Income Taxes (Topic 740): Presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. Under the amendments of this update an entity is required to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except as follows. To the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes that would result from the disallowance of a tax position or the tax law of the applicable jurisdiction does not require the entity to use, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The assessment of whether a deferred tax asset is available is based on the unrecognized tax benefit and deferred tax asset that exist at the reporting date and should be made presuming disallowance of the tax position at the reporting date. For example, an entity should not evaluate whether the deferred tax asset expires before the statute of limitations on the tax position or whether the deferred tax asset may be used prior to the unrecognized tax benefits being settled. The provisions of this update will be effective prospectively for the Company in fiscal years beginning after December 15, 2013, and for the interim periods within fiscal years with early adoption and retrospective application permitted. The Company believes the adoption of this new guidance will not have a material impact on its consolidated financial statements.

Collaboration_Agreement_with_U

Collaboration Agreement with Ucyclyd Pharma, Inc.	12 Months Ended
	Dec. 31, 2013
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 the amended and restated collaboration agreement (the “restated collaboration agreement”) under which Ucyclyd granted the Company an option to purchase all of Ucyclyd’s worldwide rights to BUPHENYL and AMMONUL at a fixed price at a future defined date, plus subsequent milestone and royalty payments, subject to Ucyclyd’s right to retain AMMONUL for a predefined price. The restated collaboration agreement superseded the collaboration agreement with Ucyclyd, dated August 23, 2007, as amended. The entry into the purchase agreement and the restated collaboration agreement resolved a dispute that the two parties had with respect to their rights under the prior collaboration agreement.
	Under the purchase agreement, the Company made a payment of $6.0 million of which (i) $5.7 million was allocated to the worldwide rights to RAVICTI and (ii) $0.3 million was allocated to the option to purchase rights to BUPHENYL and AMMONUL, based on their relative fair values. The allocated amount to the rights to RAVICTI of $5.7 million was recorded to research and development expense in the consolidated statements of operations for the period ended March 31, 2012 due to the uncertainty of an alternative future use. The allocated amount for the option to purchase rights to BUPHENYL and AMMONUL in the amount of $0.3 million was included within other current assets and was subsequently offset against the gain recognized from the settlement of retention option (see Note 4).
	The Company will also pay tiered mid to high single digit royalties on global net sales of RAVICTI and may owe regulatory milestones of up to $15.8 million related to approval of GPB in HE, regulatory milestones of up to $7.3 million per indication for approval of GPB in indications other than UCD or HE, and net sales milestones of up to $38.8 million if GPB is approved for use in indications other than UCD (such as HE) and all annual sales targets are reached.
	In addition, the intellectual property license agreements executed between Ucyclyd and Dr. Marshall L. Summar, (“Summar”) and Ucyclyd and Brusilow Enterprises, LLC, (“Brusilow”) were assigned to the Company, and the Company has assumed the royalty and milestone obligations under the Brusilow agreement for sales of RAVICTI in any indication and the royalty obligations under the Summar agreement on sales of GPB to treat HE. The Brusilow and Summar agreements provide that royalty obligations will continue, without adjustment, even if generic versions of the licensed products are introduced and sold in the relevant country.
	Under the terms of the restated collaboration agreement, the Company had an option to purchase all of Ucyclyd’s worldwide rights in BUPHENYL and AMMONUL, subject to Ucyclyd’s option to retain rights to AMMONUL. The Company was permitted to exercise this option for 90 days beginning on the earlier of the date of the approval of RAVICTI for the treatment of UCD and June 30, 2013, but in no event earlier than January 1, 2013. The upfront purchase price for AMMONUL and BUPHENYL was $22.0 million. If the RAVICTI New Drug Application (“NDA”) for UCD was not approved by January 1, 2013, then Ucyclyd was obligated to make monthly payments of $0.5 million to the Company until the earliest of (1) FDA approval of the RAVICTI NDA for UCD, (2) June 30, 2013 and (3) the Company’s written notification of the decision not to purchase Ucyclyd’s worldwide rights to BUPHENYL and AMMONUL.
	On February 1, 2013, the FDA approved RAVICTI for the treatment of UCD in adult and pediatric patients two years of age and older. In accordance with the restated collaboration agreement, Ucyclyd made a payment of $0.5 million during the quarter ended March 31, 2013.
	On April 29, 2013, the Company exercised its option to purchase BUPHENYL and AMMONUL. Ucyclyd subsequently exercised it’s time-limited right to elect to retain all rights to AMMONUL for a contractual purchase price of $32.0 million (“retention amount”). Upon closing of the transaction, Ucyclyd paid the Company a net payment of $11.0 million, which reflects the Company’s contractual purchase price for Ucyclyd’s worldwide rights to BUPHENYL in the amount of $19.0 million being off-set against Ucyclyd’s retention amount for AMMONUL and a $2.0 million payment due to Ucyclyd for inventory that the Company purchased from Ucyclyd. The Company has retained a right of first negotiation should Ucyclyd later decide to sell, exclusively license, or otherwise transfer the AMMONUL assets to a third party.

Acquisition_of_BUPHENYL_from_U

Acquisition of BUPHENYL from Ucyclyd Pharma, Inc.	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Acquisition of BUPHENYL from Ucyclyd Pharma, Inc.	'
	4	Acquisition of BUPHENYL from Ucyclyd Pharma, Inc.
	Description of the Transaction
	As discussed in Note 3, under the terms of the restated collaboration agreement, on April 29, 2013, the Company exercised its option to purchase all of Ucyclyd’s worldwide rights in BUPHENYL and AMMONUL. On May 17, 2013 Ucyclyd exercised its time-limited right to elect to retain all rights to AMMONUL. On May 31, 2013 (the “Acquisition Date”), the Company completed the acquisition of BUPHENYL. Accordingly, BUPHENYL results are included in Hyperion’s consolidated financial statements from the date of the acquisition. For the period from June 1, 2013 to December 31, 2013, BUPHENYL net revenue was $11.5 million.
	The Company acquired BUPHENYL to enhance its commercial product portfolio and to allow the Company an opportunity to serve the entire UCD patient population, including those less than two years of age or for those patients who may prefer BUPHENYL.
	Purchase Consideration and Assets Acquired
	The Company accounted for the acquisition of BUPHENYL as a business combination under the acquisition method of accounting. On the Acquisition Date, the Company received a net payment of $11.0 million, which reflected the $32.0 million retention amount for AMMONUL due to the Company less the $19.0 million contractual purchase price for BUPHENYL due to Ucyclyd and a $2.0 million payment due to Ucyclyd for inventory that the Company purchased from Ucyclyd.
	The fair value of purchase consideration was estimated based upon the fair value of assets acquired. The estimated fair value attributed to the BUPHENYL product rights was determined on a discounted forecast of the estimated net future cash flows to be generated from the product rights and has an expected useful life of 10 years. The following table summarizes the allocation of purchase price to the fair values of the assets acquired as of the acquisition date:
			(in thousands)
	Inventories		$	3,900
	Intangible Asset — BUPHENYL Product rights			16,500
	Total		$	20,400
	Gain from Settlement of Retention Option
	In connection with the allocation between the BUPHENYL acquisition described above and Ucyclyd’s exercise of its retention option, the Company recorded a gain of $31.1 million. The amount of gain is comprised of (i) fair value of BUPHENYL of $20.4 million and (ii) net cash received from Ucyclyd of $11.0 million off-set by (iii) the $0.3 million carrying value of the option to purchase the rights to BUPHENYL and AMMONUL. The following table summarizes the results of the Company’s allocation:
			(in thousands)
	Ucyclyd’s retention option amount		$	32,000
	Amount due to Ucyclyd for BUPHENYL product rights			(19,000	)
	Amount due to Ucyclyd for inventory			(2,038	)
	Net payment received from Ucyclyd			10,962
	Option to purchase the rights to BUPHENYL and AMMONUL			(283	)
	Fair value of BUPHENYL			20,400
	Gain from settlement of retention option		$	31,079
	Pro forma Impact of Business Combination
	The following consolidated pro forma information is based on the assumption that the acquisition occurred on January 1, 2012. The unaudited pro forma information is presented for comparative purposes only and is not necessarily indicative of the financial position or results of operations which would have been reported had the Company completed the acquisition during these periods or which might be reported in the future. The unaudited pro forma information reflects primarily the application of the following adjustments:
		•		the elimination of the historical intangible asset amortization expense of this acquisition;
		•		the amortization expense related to the fair value of intangible asset acquired;
		•		the exclusion of acquisition-related costs, incurred for this acquisition; and
		•		the exclusion of the step-up value related to inventory sold that was acquired as part of the acquisition.
	The unaudited pro forma information is not necessarily indicative of what the Company’s consolidated results of operations actually would have been had the acquisition been completed on January 1, 2012. In addition, the unaudited pro forma information does not purport to project the future results of operations of the Company.
			Year Ended
			December 31,
			2013			2012
			( in thousands)
	Net revenues		$	52,900		$	21,501
	Net income (loss)			24,266			(28,976	)
	Acquisition-related Costs
	Acquisition-related expenses consist of transaction costs which represent external costs directly related to the acquisition of BUPHENYL and primarily include expenditures for professional fees such as legal, accounting and other directly related incremental costs incurred to close the acquisition. Acquisition-related expenses for the year ended December 31, 2013 were $0.6 million.

Investments

Investments	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
Investments	'
	5	Investments
	All investments were classified as available-for-sale at December 31, 2013. The principal amounts of investments by contractual maturity are summarized in the tables below:
			Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
			Years Ending December  31,					Value at		Loss			Fair Value at
								December 31, 2013					December 31, 2013
			2014		2015
	Certificates of deposit		$	10,525	$	2,845		$	13,370	$	(27	)	$	13,343
	Corporate notes			6,047		12,960			19,007		(24	)		18,983
	U.S. Government agency securities			8,011		—			8,011		(3	)		8,008
	Commercial paper			3,492		—			3,492		(1	)		3,491
	Total		$	28,075	$	15,805		$	43,880	$	(55	)	$	43,825
	The Company did not hold any investments at December 31, 2012.
	The Company evaluated its investments and determined that there were no other-than-temporary impairments as of December 31, 2013.
	The aggregate amounts of unrealized losses and related fair value of investments with unrealized losses as of December 31, 2013 was as follows:
			Less Than 12 Months to					12 Months or More to					Total
			Maturity					Maturity
			Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
			Fair Value		Losses			Fair Value		Losses			Fair Value		Losses
	Certificates of deposit		$	10,507	$	(18	)	$	2,836	$	(9	)	$	13,343	$	(27	)
	Corporate notes			6,039		(8	)		12,944		(16	)		18,983		(24	)
	U.S. Government agency securities			8,008		(3	)		—		—			8,008		(3	)
	Commercial paper			3,491		(1	)		—		—			3,491		(1	)
	Total		$	28,045	$	(30	)	$	15,780	$	(25	)	$	43,825	$	(55	)

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2013
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 December 31, 2013 and 2012 (in thousands):
			Fair Value Measurements at December 31, 2013
			Quoted Price in		Significant Other		Significant		Total
			Active Markets		Observable Inputs		Unobservable
			for Identical Assets		(Level 2)		Inputs
			(Level 1)				(Level 3)
	Assets:
	Cash equivalents:
	Money market funds		$	38,506	$	—	$	—	$	38,506
	Certificates of deposit			—		480		—		480
	Total cash equivalents		$	38,506	$	480	$	—	$	38,986
	Available-for-sale securities:
	Short-term:
	Certificates of deposit		$	—	$	10,507	$	—	$	10,507
	Commercial paper			—		3,491		—		3,491
	Corporate notes			—		6,039		—		6,039
	U.S. Government agency securities			—		8,008		—		8,008
	Total short-term investments			—		28,045		—		28,045
	Long-term:
	Certificates of deposit			—		2,836		—		2,836
	Corporate notes			—		12,944		—		12,944
	Total long-term investments			—		15,780		—		15,780
	Total available-for-sale securities		$	—	$	43,825	$	—	$	43,825
			December 31, 2012
			Quoted prices in		Significant Other		Significant
			Active Markets		Observable		Unobservable
			for Identical		Inputs (Level 2)		Inputs
			Items (Level 1)				(Level 3)
	Assets:
	Cash and cash equivalents:
	Money market funds		$	45,003	$	—	$	—
			$	45,003	$	—	$	—
	The following table presents the carrying value and estimated fair value of the Company’s notes payable as of December 31, 2013 (in thousands):
			December 31, 2013
			Carrying		Estimated
			Value		Fair Value
	April and September 2012 Notes		$	8,273	$	8,860
	Valuation Techniques
	The Company classifies money market funds, which are valued based on quoted market prices in active markets with no valuation adjustment, as Level 1 assets within the fair value hierarchy.
	Items classified as Level 2 within the valuation hierarchy consist of commercial paper, corporate notes, U.S. government agency securities and certificates of deposit. The Company estimates the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. The Company validates the prices provided by our third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.
	Items classified as Level 3 within the valuation hierarchy consist of April and September 2012 Notes. 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	12 Months Ended
	Dec. 31, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	7	Inventories
	The following table represents the components of inventories (in thousands):
			December 31,		December 31,
			2013		2012
	Raw Materials		$	697	$	—
	Finished goods			2,816		—
	Total		$	3,513	$	—
	As discussed in Note 4, on May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. As part of the acquisition, the Company purchased inventories from Ucyclyd and the Company recorded these inventories at fair value in the amount of $3.9 million on the Acquisition Date. As of December 31, 2013, the Company has $0.4 million of inventory from the acquisition of BUPHENYL.

Intangible_Asset

Intangible Asset	12 Months Ended
	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Intangible Asset	'
	8	Intangible Asset
	As discussed in Notes 3 and 4, the Company acquired BUPHENYL and as part of this transaction, the Company recognized a $16.5 million intangible asset relating to BUPHENYL product rights. The estimated fair value attributed to the BUPHENYL product rights was determined on a discounted forecast of the estimated net future cash flows to be generated from the product rights. The intangible asset is amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefits of the intangible asset are consumed as revenue is generated. The pattern of consumption of the economic benefits is estimated using the future projected cash flows of the intangible asset. The Company estimated the useful life of the BUPHENYL product rights to be 10 years.
	Intangible asset amortization expense was $3.1 million for the year ended December 31, 2013.
	Estimated aggregate amortization expense for each of the five succeeding years ending December 31 is as follows (in thousands):
			2014		2015		2016		2017		2018
	Amortization expense		$	4,053	$	3,294	$	1,157	$	1,048	$	1,012

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Property and Equipment	'
	9	Property and Equipment
	The following table represents the components of property and equipment (in thousands):
			December 31,			December 31,
			2013			2012
	Computers and Software		$	563		$	95
	Furniture and Fixtures			320			—
	Office Equipment			53			21
	Leasehold Improvements			—			247
	Capital work in progress			264			—
				1,200			363
	Less: Accumulated depreciation			(264	)		(314	)
	Total property and equipment, net		$	936		$	49
	Capital work in progress includes implementation cost related to certain modules within the Company’s Enterprise Resource Planning system. Depreciation expense for the years ended December 31, 2013, 2012 and 2011 was $0.2 million, $15,000 and $0.1 million, respectively.

Accrued_Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2013
Payables And Accruals [Abstract]	'
Accrued Liabilities	'
	10	Accrued Liabilities
	The following table represents the components of accrued liabilities (in thousands):
			December 31,
			2013		2012
	Preclinical and clinical trial expenses		$	246	$	583
	Payroll and related expenses			4,278		1,457
	Gross to net sales accruals			5,235		—
	Royalty payable			1,154		—
	State taxes payable			326		—
	Interest payable			61		93
	Other			887		407
			$	12,187	$	2,540

Notes_Payable

Notes Payable	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Notes Payable	'
	11	Notes Payable
	April 2011 Convertible Notes Payable
	In April 2011, the Company entered into a convertible notes financing (the “April 2011 convertible notes financing”), in which it issued an aggregate principal amount of $17.5 million of convertible notes in an initial closing in April and an aggregate principal amount of $8,285 of convertible notes in subsequent closings in May 2011 (collectively, the “April 2011 Notes”) pursuant to the Convertible Note and Warrant Purchase Agreement dated April 1, 2011 (the “April 2011 Purchase Agreement”). The April 2011 Purchase Agreement permits the Company to issue up to an aggregate principal amount of $35.0 million.
	The April 2011 Notes accrue interest at a rate of 6% per annum and have a maturity date of the earliest of (i) demand by the holders of 66% of the principal amount of the then-outstanding April 2011 Notes under certain circumstances, which demand may not be made earlier than December 31, 2012, as amended or (ii) an event of default. The April 2011 Notes cannot be prepaid, except on demand by the holders of the April 2011 Notes, as described above. The principal and the interest under the April 2011 Notes are automatically convertible (i) into securities that are sold in an issuance of preferred stock generating gross proceeds of at least $30.0 million, referred to herein as a qualified financing, at the lowest price at which such securities are sold to certain new investors in the qualified financing, (ii) into Series C-2 convertible preferred stock upon the occurrence of certain change of control events, unless the holders of 66% of the principal amount of the then-outstanding April 2011 Notes notify the Company of their election to accelerate the unpaid principal and interest of the April 2011 Notes in connection with the change of control event, or (iii) into common stock immediately prior to the consummation of an initial public offering, at a conversion price equal to the initial public offering price. In addition, holders of 66% of the principal amount of the then-outstanding April 2011 Notes have the option to convert the April 2011 Notes (i) in the event that the Company consummates an equity financing that is not a “qualified financing,” as described above, prior to the maturity of the April 2011 Notes, into the equity securities issued in the equity financing, or (ii) upon maturity of the April 2011 Notes, if the April 2011 Notes have not been previously converted, into shares of the Company’s Series C-2 convertible preferred stock.
	On July 31, 2012, upon closing of the IPO, the principal and accrued interest under the Company’s April 2011 Notes amounting to $18.9 million converted into 1,888,054 shares of common stock. The carrying value, including the impact of the amendment to the April 2011 Notes as discussed below and accrued interest under the Company’s April 2011 Notes was $18.4 million as of July 31, 2012.
	April 2011 Call Option Liability
	The April 2011 Purchase Agreement also provides that so long as there has not been a qualified financing, change of control or initial public offering, on or before June 30, 2011, or in the event that the April 2011 Notes issued in an initial closing or subsequent initial closing have not been previously converted into common or preferred stock as set forth in the April 2011 Purchase Agreement, upon the election and approval of the holders of 66% of the principal amount of the then-outstanding April 2011 Notes, the Company will issue (i) notes with an aggregate principal amount of up to $7.5 million in the event that none of the subsequent closing notes have been issued or (ii) up to an aggregate principal amount of $10.5 million in the event all or a portion of the subsequent closing notes have been issued. The additional note amount was determined to be a call option (“April 2011 Call Option”) that was recorded at its fair value of $0.9 million as a debt discount that has been amortized to interest expense over the term of the April 2011 Notes. The fair value of the April 2011 Call Option was determined using the Black-Scholes option-pricing model on the date of the issuance using the following assumptions: expected life of 7 months, risk free interest rate of 0.27%, dividend yield of 0% and expected volatility of 50%. During the year ended December 31, 2011, the Company recorded $0.3 million in other income (expense), net to reflect the change in the fair value of the April 2011 Call Option, and $0.6 million in the gain on the extinguishment of debt to reflect the termination of the April 2011 Call Option in October 2011.
	Amendment to the April 2011 Convertible Notes Payable
	In October 2011, the Company substantially amended the April 2011 Purchase Agreement to extend the term of the April 2011 Notes from January 31, 2012 to December 31, 2012, and to terminate the April 2011 Call Option. As a result, the transaction was accounted for as an extinguishment of debt in the amount of $1.1 million, which includes $0.6 million on termination of the April 2011 Call Option, calculated as the excess of the carrying amount of the notes, including accrued interest, over the fair value of the amended notes. In accordance with ASC 470-50-40-2, the Company reflected the gain on extinguishment of debt resulting from this related party transaction as a capital contribution and credited this amount to additional paid-in capital within the consolidated statements of stockholders’ equity (deficit).
	October 2011 Convertible Notes Payable
	In October 2011, the Company entered into a convertible notes financing (the “October 2011 convertible notes financing”), in which it issued an aggregate principal amount of $7.5 million of convertible notes in an initial closing in October and an aggregate principal amount of $3,551 of convertible notes in a subsequent initial closing in November 2011 and aggregate amount of $7.5 million of convertible notes in the second closing in February 2012 (collectively, the “October 2011 Notes”) pursuant to the Convertible Note and Warrant Purchase Agreement dated October 26, 2011 (the “October 2011 Purchase Agreement”). The October 2011 Purchase Agreement permitted the Company to issue up to an aggregate principal amount of $15.0 million.
	The October 2011 Notes accrue interest at a rate of 6% per annum and have a maturity date of the earliest of (i) demand by the holders of 66% of the principal amount of the then-outstanding October 2011 Notes under certain circumstances, which demand may not be made earlier than December 31, 2012, or (ii) an event of default. The October 2011 Notes cannot be prepaid, except on demand by the holders of the October 2011 Notes, as described above. The principal and the interest under the October 2011 Notes are automatically convertible (a) into securities that are sold in an issuance of preferred stock generating gross proceeds of at least $40.0 million, referred to herein as a qualified financing, equal to the quotient of (i) the outstanding principal amount plus unpaid accrued interest divided by (ii) the price per share paid by the investors purchasing new preferred stock in the qualified financing; (b) upon the occurrence of certain change in control events, into new series of preferred stock equal to the quotient of (i) the outstanding principal amount plus accrued interest divided by (ii) the Series C-2 original issue price, or (c) into common stock immediately prior to the consummation of an initial public offering, at a conversion price equal to the initial public offering price. In addition, holders of 66% of the principal amount of the then-outstanding October 2011 Notes have the option to convert the October 2011 Notes (i) in the event that the Company consummates an equity financing that is not a “qualified financing,” as described above, prior to the maturity of the October 2011 Notes, into the equity securities issued in the equity financing, or (ii) upon maturity of the October 2011 Notes, if the October 2011 Notes have not been previously converted, into shares of the Company’s Series C-2 convertible preferred stock.
	On July 31, 2012, upon closing of the IPO, the principal and accrued interest under the Company’s October 2011 Notes amounting to $15.6 million converted into 1,556,816 shares of common stock. The carrying value, (net of discount) and accrued interest under the Company’s October 2011 Notes was $14.9 million as of July 31, 2012.
	October 2011 Call Option Liability
	The October 2011 Purchase Agreement also provides that so long as there has not been a qualified financing, change of control or initial public offering, on or before June 30, 2012, or in the event that the October 2011 Notes issued in the initial closing or subsequent initial closings have not been previously converted into common or preferred stock as set forth in the agreement, upon the election and approval of the holders of 66% of the principal amount of the then-outstanding October 2011 Notes, the Company will issue (i) notes with an aggregate principal amount of $7.5 million or (ii) up to $7.5 million of notes in the event all or a portion of the subsequent initial closing notes have been issued. The additional note amount was determined to be a call option (“October 2011 call option”) that was recorded at its fair value of $0.8 million as a debt discount that has been amortized to interest expense over the term of the October 2011 Notes. The fair value of the October 2011 call option was determined using the Black-Scholes option-pricing model on the date of issuance using the following assumptions: expected life of 8 months, risk free interest rate of 0.12%, dividend yield of 0% and expected volatility of 50%. During the year ended December 31, 2011, the Company recorded $0.1 million in other income (expense), net to reflect the change in the fair value of the October 2011 Call Option. The Company determined the fair value of the October 2011 Call Option at December 31, 2011 to be $0.7 million, using the Black-Scholes option-pricing model with the following assumptions: expected life of 6 months, risk-free interest rate of 0.12%, dividend yield of 0% and expected volatility of 50%.
	The Company recorded $0.7 million to other income (expense), net in its consolidated statements of operations upon issuance of the second closing of the October 2011 Notes in February 2012 for $7.5 million.
	As of December 31, 2012, the April 2011 Notes and October 2011 Notes were no longer outstanding as they had converted into shares of common stock upon the closing of the Company’s IPO on July 31, 2012.
	During the year ended December 31, 2012, the Company recorded amortization for debt discount of $0.9 million related to the October 2011 Notes. During the year ended December 31, 2011, the Company recorded amortization for the debt discount of $1.6 million related to the April 2011 Notes and October 2011 Notes.
	In addition, the Company determined that the April 2011 Notes and the October 2011 Notes have contingent beneficial conversion features related to the conversion options described above. Upon the occurrence of the contingent event underlying those conversion options, the Company may recognize a charge based on the difference, if any, between the adjusted conversion price and the fair market value of common stock at the original issuance date. This charge, if any, will impact net income (loss) attributable to common stockholders and basic and diluted net income (loss) per share attributable to common stockholders.
	The Company determined that no beneficial conversion features exist at the dates of issuance of the April 2011 Notes and October 2011 Notes and upon closing of the IPO on July 31, 2012, at which time these notes were converted to common stock.
	April 2012 and September 2012 Notes Payable
	In April 2012, the Company borrowed $10.0 million (the “April 2012 Notes”) pursuant to a loan and security agreement (the “Loan Agreement”) with Silicon Valley Bank and Leader Lending, LLC—Series B (the “Lenders”). The loan carries an interest rate of 8.88%, with interest only payments for the period of 9 months from May 1, 2012. The loan is then payable in equal monthly principal payments plus interest over a period of 27 months from February 1, 2013. In connection with the Loan Agreement, the Company granted a security interest in all of its assets, except intellectual property. The Company’s obligations to the Lenders include restrictions on borrowing, asset transfers, placing liens or security interest on its assets including the Company’s intellectual property, mergers and acquisitions and distributions to stockholders. The Loan Agreement also requires the Company to provide the Lenders monthly financials and compliance certificate within 30 days of each month end, annual audited financials within 180 days of each fiscal year-end and annual approved financial projections. The Company issued warrants to the Lenders to purchase a total of 75,974 shares of common stock with an exercise price of $4.08 per share. The Loan Agreement requires immediate repayment of amounts outstanding upon an event of default, as defined in the Loan Agreement, which includes events such as a payment default, a covenant default or the occurrence of a material adverse change, as defined in the Loan Agreement. In addition, a final payment equal to 6.5% of the principal loan amount is due on the earlier of (i) maturity date, (ii) prepayment of the loan or (iii) an event of default. Pursuant to the terms of the Loan Agreement, once the Company raises at least $30.0 million from the sale of equity securities or subordinated debt, the Lenders also agreed to lend the Company a one-time single loan in the amount of $2.5 million (the “Bank Term Loan”). In September 2012, the Company borrowed an additional $2.5 million (the “September 2012 Note”) from Silicon Valley Bank pursuant to the terms of the Bank Term Loan. In addition, the Company issued warrants to Silicon Valley Bank to purchase a total of 8,408 shares of common stock with an exercise price of $5.05 per share. A final payment equal to 6.5% of the principal loan amount is due on the earlier of (i) maturity date, (ii) prepayment of the loan or (iii) an event of default. The principal amount outstanding under the Bank Term Loan accrues interest at a per annum rate equal to the greater of (i) 8.88% and (ii) the Treasury Rate, as defined in the Loan Agreement, on the date the loan is funded plus 8.50%, with interest only payments for the period of 9 months from the date the loan is funded. The loan is then payable in equal monthly principal payments plus interest over a period of 27 months from the date the loan is funded.
	During the year ended December 31, 2013 and 2012, the Company recorded amortization for debt discount of $0.5 million and $0.4 million, respectively, related to the April 2012 Notes and September 2012 Note.
	Future minimum payments under the April 2012 and September 2012 Notes as of December 31, 2013 are as follows (in thousands):
	Years Ending December 31,
	2014		$	6,152
	2015			3,376
	Total future minimum payments		$	9,528
	Less: amount representing unamortized interest			(563	)
	Less: amount representing debt discount			(692	)
	Total minimum payments		$	8,273
	Less: current portion			(5,652	)
	Non-current portion		$	2,621

Warrants

Warrants	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Warrants	'
	12	Warrants
	October 2007 Common Stock 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 December 31, 2013.
	April 2008 Common Stock Warrants
	In exchange for services received, the Company issued a warrant to purchase 22 shares of common stock at an exercise price of $327.95 per share in April 2008 (the “April 2008 common stock warrants”). The fair value of the warrant was $4,500 which was determined using the Black-Scholes option pricing model with the following assumptions: volatility of 71%; risk-free rate of 2.84%; and exercise price of $327.95 and an expected term of five years. The April 2008 common stock warrants expired as of December 31, 2012.
	April 2011 Common Stock Warrants
	In connection with the April 2011 convertible notes financing, the Company issued warrants to purchase shares of the Company’s common stock in an initial closing in April 2011 and in subsequent closings in May 2011 (collectively, the “April 2011 common stock warrants”) both at an exercise price of $4.08 per share and subject to adjustments upon the occurrence of certain events, including but not limited to a capital reorganization, reclassification or subdivision of common shares. The number of shares of common stock are calculated based on 30% of the principal amount of the April 2011 Notes divided by either (i) in the event that the holder’s notes have been converted into shares of new preferred stock, the price per share paid by a new investor in a qualified financing, (ii) in the event that the holder’s April 2011 Notes have been converted into shares of Series C-2 preferred stock, the Series C-2 original issue price of $9.62, (iii) in the event that the holder’s April 2011 Notes have been converted into equity securities in a non-qualified financing, the price paid per share by an investor in a non-qualified financing, or (iv) a price of $9.62 in the event of an initial public offering. The April 2011 common stock warrants are exercisable until April 2021.
	On July 31, 2012, immediately prior to the closing of the IPO, the April 2011 common stock warrants automatically net exercised into 322,599 shares of common stock.
	October 2011 Preferred Stock Warrants
	In connection with the October 2011 convertible notes financing (Note 6), the Company issued warrants to purchase shares of the Company’s preferred stock, in an initial closing in October 2011, and in a subsequent initial closing in November 2011 and in the second closing in February 2012 (collectively, the “October 2011 preferred stock warrants”) both at exercise prices subject to adjustments upon the occurrence of certain events, including but not limited to a capital reorganization, reclassification or subdivision of common shares. The number of shares of preferred stock are calculated based on 30% of the principal amount of the October 2011 Notes divided by either: (i) the price per share paid by the investors for the new preferred stock in the qualified financing; (ii) Series C-2 preferred stock original price at $9.62; (iii) price per share paid by the investors for equity securities in the nonqualified financing, or (iv) a price of $9.62 in the event of an initial public offering. These October 2011 preferred stock warrants are exercisable until October 25, 2018. The additional preferred stock warrants issued in February 2012 are exercisable until February 7, 2019.
	On July 31, 2012, immediately prior to the closing of the IPO, the October 2011 preferred stock warrants automatically net exercised into 17,762 shares of common stock.
	April 2012 Common Stock Warrants
	In connection with the Loan Agreement entered into in April 2012, the Company issued warrants to the Lenders to purchase a total of 75,974 shares of common stock. The warrants are exercisable at $4.08 per share and expire in April 2022 (the “April 2012 common stock warrants”). The April 2012 common stock warrants have been fully exercised.
	September 2012 Common Stock Warrants
	In connection with the September 2012 Note, the Company issued warrants to the Lender to purchase a total of 8,408 shares of common stock. The warrants are exercisable at $5.05 per share and expire in September 2022 (the “September 2012 common stock warrants”). The September 2012 common stock warrants have been fully exercised.
	Common and Preferred Stock Warrants Fair Value Measurements
	Under ASC 815 and ASC 480, the Company accounts for the April 2011 common stock warrants and the October 2011 preferred stock warrants, respectively, at fair value and recorded them as liabilities on the date of issuance. The Company accounts for the April 2012 and September 2012 common stock warrants at fair value and recorded them as equity on the date of issuance. Because the April 2012 and September 2012 common stock warrants meet the requirements for equity classification under ASC 815, the Company is not required to re-measure the fair value of the warrants subsequent to the date of issuance.
	On the date of issuance and in subsequent re-measurements, the Company determined the fair value of the April 2011 and October 2011 warrants by allocating the Company equity value using the Black-Scholes option-pricing model at each reporting date. The Company’s equity value was allocated among the various convertible debt and equity classes expected to be outstanding at the liquidity events based on the rights and preferences of each class.
	The fair value of the April 2011 common stock warrants as of the date of issuance was determined to be $1.1 million, which was recorded as a debt discount and amortized to interest expense over the term of the April 2011 Notes. The fair value was determined using the following assumptions: expected life of 2 years; risk free interest rate of 0.80%; and expected volatility of 70%.
	The fair value of the October 2011 preferred stock warrants as of the date of issuance was determined to be $0.4 million, which was recorded as a debt discount and amortized to interest expense over the term of the October 2011 Notes. The fair value was determined using the following assumptions: expected life of 1.50 years; risk free interest rate of 0.12%; and the expected volatility of 70%. The fair value of the preferred stock warrants issued in February 2012 in connection with the second closing of the October 2011 Notes was determined to be $0.5 million, which was recorded as a debt discount and amortized to interest expense over the term of the October 2011 Notes. The fair value was determined using the following assumptions: expected life of 1 year; risk free interest rate of 0.20%; and expected volatility of 70%.
	The fair value of the April 2012 common stock warrants as of the date of issuance was determined to be $0.7 million, which was recorded as a debt discount and amortized to interest expense over the term of the April 2012 Notes. Using the Black-Scholes option-pricing model, the fair value was determined using the following assumptions: expected life of 10 years; risk free interest rate of 1.98%; and expected volatility of 70%.
	The fair value of the September 2012 common stock warrants as of the date of issuance was determined to be $75,000, which was recorded as a debt discount and amortized to interest expense over the term of the September 2012 Note. Using the Black-Scholes option-pricing model, the fair value was determined using the following assumptions: expected life of 10 years; risk free interest rate of 1.65%; and expected volatility of 65%.
	For the year ended December 31, 2012, the Company recorded $1.5 million of expense in other income (expense), net, to reflect the change in fair value of the April 2011 common stock warrants. For the year ended December 31, 2012, the Company recorded $0.7 million of income in other income (expense), net, to reflect the change in fair value of the October 2011 preferred stock warrants.
	As of December 31, 2012, the April 2011 common stock warrants and October 2011 preferred stock warrants were no longer outstanding as they had automatically net exercised into shares of common stock upon the closing of the Company’s IPO on July 31, 2012. As a result, the fair value of the April 2011 common stock warrants and October 2011 preferred stock warrants as of July 31, 2012, estimated to be $3.9 million using the Black-Scholes option-pricing model, was reclassified to additional paid-in capital. The Company recorded $0.8 million to other income (expense), net, arising from final measurement of 2011 common and preferred stock warrants at the closing date of IPO.
	The following table summarizes the outstanding warrants and the corresponding exercise price as of December 31, 2013 and 2012:
			Number of Shares				Per Share
			Outstanding				Exercise Price
			December 31,
			2013		2012
	October 2007 common stock warrants			274		274	$	1,913.05
	April 2012 common stock warrants			—		75,974		4.08
	September 2012 common stock warrants			—		8,408		5.05
	Total			274		84,656

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	13	Commitments and Contingencies
	Operating Leases
	On October 14, 2013, the Company entered into a lease agreement with 2000 Sierra Point Parkway LLC (“Landlord”) under which the Company will lease approximately 20,116 rentable square feet of office space in Brisbane, California. The initial term of the lease is six years and the lease commencement date is November 19, 2013. On December 12, 2013, the Company entered into the First Amendment to the Lease (“First Amendment”) under which the Company will lease approximately 352 rentable square feet of storage space. In addition to operating expenses and certain other additional expenses set forth in the Leases, the Company will pay total base rent of approximately $4.5 million during the initial term of the Leases.
	The Company recognizes rent expense on a straight-line basis over the lease period with monthly base rent of approximately $0.1 million. In addition, the Company also leases certain office equipment under an operating lease, which expires in December 2016.
	Aggregate total future minimum lease payments under operating facility and equipment leases as of December 31, 2013 were as follows (in thousands):
	Years Ending December 31,
	2014		$	518
	2015			797
	2016			820
	2017			821
	2018			845
	Thereafter			766
	Total		$	4,567
	Rent expense including maintenance fees was $0.4 million for the year ended December 31, 2013, $0.3 million for the year ended December 31, 2012 and $0.4 million for the year ended December 31, 2011.
	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.

Preferred_Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Preferred Stock	'
	14	Preferred Stock
	On July 31, 2012, upon the closing of the IPO, the Company’s Series C-1 and Series C-2 preferred stock amounting to $58.3 million converted into 1,912,598 and 4,663,039 shares of common stock, respectively. On July 31, 2012, the Company amended its Certificate of Incorporation to decrease the number of authorized shares of preferred stock to 10,000,000 with a par value of $0.0001 per share. Pursuant to the Company’s amended and restated certificate of incorporation, the board of directors has the authority, without action by its stockholders, to designate and issue shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof.
	As of December 31, 2013 and 2012, there was no preferred stock outstanding.
	2009 Preferred Stock Liability
	In June 2009, the Company entered into a tranched Series C-2 convertible preferred stock transaction. In connection with the initial closing in June 2009, the Company agreed to issue to the purchasers and the purchasers agreed to purchase from the Company an aggregate of 2,331,116 shares of Series C-2 convertible preferred stock at a purchase price of $9.62 per share in a subsequent sale of Series C-2 preferred stock. The Company determined that the liability to issue Series C-2 convertible preferred stock shares at a future date was a freestanding instrument and should be accounted as a liability under ASC 480. The fair value of this freestanding instrument was determined using the Black-Scholes option pricing model on the date of the issuance of the first tranche and was recorded as a liability in the amount of $1.4 million. The Company used the following assumptions: expected life of 1 year, risk-free interest rate of 0.56% and expected volatility of 45%.
	At December 31, 2009, the fair value of the freestanding instrument was re-measured at $0.7 million using the following assumptions: expected life of 0.5 years, risk-free interest rate of 0.20% and expected volatility of 45%. As a result, the Company recorded $0.6 million to other income (expense), net in the consolidated statement of operations.
	In April 2010, upon the issuance of the second tranche of the Series C-2 convertible preferred stock, the fair value of the freestanding instrument was re-measured using the following assumptions: expected life of 0.25 years, risk-free interest rate of 0.16% and expected volatility of 45%. Accordingly, in 2010, the Company recorded $1.1 million to other income (expense), net in its consolidated statement of operations. The fair value of preferred stock liability in the amount of $0.4 million was offset against the proceeds received from the issuance of preferred stock on the date of issuance of the second tranche of Series C-2 convertible preferred stock.
	On July 31, 2012, upon closing of the IPO, the Company’s outstanding Series C-2 preferred stock converted into shares of common stock.

Common_Stock

Common Stock	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Common Stock	'
	15	Common Stock
	On July 31, 2012, the Company completed its IPO and issued 5,000,000 shares of its common stock at an initial offering price of $10.00 per share. In addition, the Company sold an additional 750,000 shares of common stock directly to its underwriters when they exercised their over-allotment option in full at the initial offering price of $10.00 per share. The shares began trading on the NASDAQ Global Market on July 26, 2012. The Company received net proceeds from the IPO of $51.3 million, after deducting underwriting discounts and commissions of $4.0 million and expenses of $2.2 million.
	On July 31, 2012, upon the closing of the IPO, the Company’s Series C-1 and Series C-2 preferred stock amounting to $58.3 million converted into 1,912,598 and 4,663,039 shares of common stock, respectively. In addition, the principal and accrued interest under the Company’s April 2011 Notes and October 2011 Notes amounting to $18.9 million and $15.6 million, respectively, converted into 1,888,054 and 1,556,816 shares of common stock. As of July 31, 2012, the carrying values and accrued interest under the April 2011 Notes and October 2011 Notes amounted to $18.4 million and $14.9 million, respectively. Additionally, the April 2011 common stock warrants and October 2011 preferred stock warrants were converted into 322,599 and 17,762 shares of common stock, respectively, immediately prior to the closing of the IPO. The fair value of the April 2011 common stock warrants and October 2011 preferred stock warrants as of July 31, 2012 of $3.9 million was reclassified to additional paid-in capital.
	In addition, on July 31, 2012, the Company amended its Certificate of Incorporation to increase the number of authorized shares of common stock to 100,000,000 with a par value of $0.0001 per share.
	Common stockholders are entitled to dividends when and if declared by the Board of Directors subject to prior rights of the preferred stockholders. The holder of each share of common stock is entitled to one vote.
	On March 13, 2013, the Company completed a follow-on offering and issued 2,875,000 shares of its common stock at an offering price of $20.75 per share. In addition, the Company sold an additional 431,250 shares of common stock directly to its underwriters when they exercised their over-allotment option in full at an offering price of $20.75 per share. 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 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 December 31, 2013, there were no sales of any securities registered pursuant to the shelf registration statement.
	At December 31, 2013, the Company had reserved common stock for future issuances as follows:
	Issuance of options under 2012 stock plan		576,760
	Issuance upon exercise of options under the 2006 and 2012 stock plan		2,790,629
	Issuance upon vesting of restricted stock awards under the 2012 stock plan		18,000
	Issuance upon exercise of common stock warrants		274
	Total		3,385,663

Stock_Option_Plan

Stock Option Plan	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Option Plan	'
	16	Stock Option Plan
	2006 Plan
	In December 2006, the Company adopted the 2006 Equity Incentive Plan (the “2006 Plan”), under which 457 shares of the Company’s common stock had been originally reserved for issuance to employees, directors and consultants. The 2006 Plan provides for the grant of the following stock awards: incentive stock options, non-statutory stock options, restricted stock awards, restricted stock unit awards and stock appreciation rights. Incentive stock options may be granted only to Company employees, which include officers and directors of the Company. Non-statutory stock options and stock purchase rights may be granted to employees and consultants. Stock awards other than incentive stock options may be granted to employees, directors and consultants.
	The Board of Directors has the authority to determine to whom options will be granted, the number of options, the term and the exercise price. The exercise price of the stock option shall not be less than 100% of the fair market value of the common stock subject to the option on the date the option is granted. For individuals holding more than 10% of the voting rights of all classes of stock, the exercise price of an option will not be less than 110% of fair market value and the option is not exercisable after the expiration of five years from the date of the grant. Options granted to an employee who is not an officer, director or consultant shall provide for vesting of the total number of shares of common stock at a rate of at least 20% per year over five years from the date the option was granted, subject to reasonable conditions such as continued employment, at any time or during any period established by the Company. The contractual term of each option is ten years.
	On July 25, 2012, the effective date of the 2012 Plan, the 2006 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.
	Activity under the 2006 Plan is as follows:
						Outstanding Options
			Number of Shares			Number of Shares			Weighted-Average
			Available for			Underlying			Exercise Price  Per
			Grant			Outstanding			Share
						Options
	Balances at December 31, 2012			—			1,661,522			3.73
	Options exercised			—			(100,280	)		4.62
	Options cancelled			23,046			(23,046	)		5.68
	Options re-allocated to 2012 Plan			(23,046	)		—			—
	Balances at December 31, 2013			—			1,538,196		$	3.64
	The aggregate intrinsic value of options exercised for the year ended December 31, 2013 was $1.7 million. Intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that had exercise prices that were lower than the fair value per share of the common stock on the date of exercise.
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2013 for the 2006 plan are as follows (dollars in thousands except per share values):
	Options Outstanding											Options Vested and Exercisable
	Exercise		Number			Aggregate			Weighted			Number			Aggregate		Exercise
	Price		Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
						Value			Remaining						Value
									Life (in Years)
	$    1.28			821,322		$	15,556			5.9			820,056		$	15,532	$	1.28
	$    4.08			305,873			4,937			7.3			209,603			3,383	$	4.08
	$    7.31			410,061			5,294			8.3			228,207			2,946	$	7.31
	$    327.95			940			—			4			940			—	$	327.95
				1,538,196		$	25,787			6.8			1,258,806		$	21,861
	The intrinsic values of outstanding, vested and exercisable options were determined by multiplying the number of shares by the difference in exercise price of the options and the fair value of the common stock as of December 31, 2013 of $20.22 per share.
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2012 are as follows (dollars in thousands except per share values):
	Options Outstanding											Options Vested and Exercisable
	Exercise		Number			Aggregate			Weighted			Number			Aggregate		Exercise
	Price		Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
						Value			Remaining						Value
									Life (in Years)
	$1.28			836,292		$	8,363			6.9			814,675		$	8,147	$	1.28
	$4.08			373,037			2,686			8.3			153,564			1,106	$	4.08
	$7.31			451,253			1,791			9.3			75,201			299		7.31
	$327.95			940			—			5			940			—	$	327.95
				1,661,522		$	12,840			7.9			1,044,380		$	9,552
	The intrinsic values of outstanding, vested and exercisable options were determined by multiplying the number of shares by the difference in exercise price of the options and the fair value of the common stock as of December 31, 2012 of $11.28 per share.
	For the year ended December 31, 2013, options vested and expected to vest for the 2006 plan aggregated to 1,528,777 options with an intrinsic value of $25.7 million, weighted average exercise price of $3.63 per share and the weighted average remaining life of 6.8 years.
	For the year ended December 31, 2012, for the 2006 plan, options vested and expected to vest is the same as options vested.
	2012 Plan
	In April 2012, the board of directors of the Company adopted (approved by Company’s stockholders in July 2012) the 2012 Omnibus Incentive Plan (the “2012 Plan”). 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.
	As of December 31, 2013 and 2012, the Company had reserved 576,760 shares and 907,908 shares of common stock, respectively, for issuance under the 2012 Plan.
	Activity under the 2012 Plan is as follows:
						Outstanding Options						Restricted Stock Units
												Outstanding
			Number of Shares			Number of Shares			Weighted-Average			Number of Shares			Grant
			Available for			Underlying			Exercise Price  Per			Underlying			Date
			Grant			Outstanding			Share			Outstanding			Fair Value
						Options						RSU’s
	Balances at December 31, 2012			907,908			267,232			10.6			—			—
	Additional shares authorized			665,850			—			—			—			—
	Options and awards granted			(1,088,315	)		1,067,315			22.9			21,000			19.39
	Options exercised			—			(16,843	)		10.33			—			—
	Options re-allocated to 2012 Plan			23,046			—			—			—			—
	Options and awards cancelled			68,271			(65,271	)		17.01			(3,000	)		—
	Balance at December 31, 2013			576,760			1,252,433		$	20.75			18,000		$	19.39
	The aggregate intrinsic value of options exercised for the year ended December 31, 2013 was $0.2 million.
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2013 for the 2012 plan are as follows (dollars in thousands except per share values):
			Options Outstanding									Options Vested and Exercisable
Exercise Price		Number			Aggregate			Weighted			Number			Aggregate		Exercise
		Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
					Value			Remaining						Value
								Life (in Years)
$10.32- 11.28			225,768		$	2,183			8.8			86,531		$	837	$	10.32 - 11.28
$18.24- 19.39			188,000			257			9.1			—			—		18.24 - 19.39
$20.07- 21.45			121,625			4			9.5			—			—		20.07 - 21.45
$22.00- 22.06			86,200			—			9.5			—			—		22.00 - 22.06
$24.38- 24.94			536,140			—			9.3			—			—		24.38 - 24.94
$25.05- 26.50			94,700			—			9.5			—			—		25.05 - 26.50
			1,252,433		$	2,444			9.2			86,531		$	837
The intrinsic values of options vested and exercisable options as of December 31, 2013 were determined by multiplying the number of shares by the difference in exercise price of the options and the fair value of the common stock as of December 31, 2013 of $20.22 per share.
Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2012 for the 2012 plan are as follows (dollars in thousands except per share values):
		Options Outstanding									Options Vested and Exercisable
Exercise Price		Number			Aggregate			Weighted			Number			Aggregate		Exercise
		Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
					Value			Remaining						Value
								Life (in Years)
$10.32			20,000		$	19			9.7			1,666		$	2	$	10.32
$10.33			117,732			112			9.6			—			—		—
$10.61			69,500			47			10			—			—		—
$10.95			15,000			5			9.8			625			0.2	$	10.95
$11.28			45,000			—			10			—			—		—
			267,232		$	183			9.8			2,291		$	2.2
The intrinsic values of options vested and exercisable options as of December 31, 2012 were determined by multiplying the number of shares by the difference in exercise price of the options and the fair value of the common stock as of December 31, 2012 of $11.28 per share.
For the year ended December 31, 2013, options vested and expected to vest for the 2012 plan aggregated to 1,209,345 options with an aggregate intrinsic value of $2.4 million, weighted average exercise price of $20.72 per share and the weighted average remaining life of 8.7 years.
For the year ended December 31, 2012, for the 2012 plan, options vested and expected to vest is the same as options vested.
Stock-Based Compensation
During the years ended December 31, 2013, 2012 and 2011 , the Company granted stock options to employees to purchase 1,067,315, 720,580 and 407,946 shares of common stock, respectively, with a weighted-average grant date fair value of $22.90, $6.76 and $2.37 per share, respectively. During the year ended December 31, 2013, the Company granted 21,000 restricted stock units to employees. The Company did not grant any restricted stock units for the years ended December 31, 2012 and December 31, 2011. Stock-based compensation expense recognized during the years ended December 31, 2013, 2012 and 2011 includes compensation expense for stock-based awards granted to employees based on the grant date fair value estimated in accordance with the provisions of ASC 718 of $4.3 million, $0.9 million and $0.3 million, respectively. As of December 31, 2013, there was a total unrecognized compensation cost of $12.7 million related to unvested stock-based awards granted. These amounts are expected to be recognized over a period of approximately 2.68 years.
The Company determines the fair value of restricted stock units using the closing price of the Company’s common stock on the date of grant. The Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options and restricted stock units are being amortized on a straight-line basis over the requisite service period of the awards. The fair value of the employee stock options was estimated using the following weighted-average assumptions:
		Year Ended December 31,
		2013			2012			2011
Expected volatility			58	%		65	%		62	%
Risk-free interest rate			1.14	%		1.05	%		2.48	%
Dividend yield			0	%		0	%		0	%
Expected term (in years)			5.96			6			6.01
Determining Fair Value of Stock Options
The fair value of each grant of stock options was determined by the Company using the methods and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine.
Expected Term — The expected term of stock options represents the weighted average period the stock options are expected to be outstanding. For option grants that are considered to be “plain vanilla”, the Company has opted to use the simplified method for estimating the expected term as provided by the Securities and Exchange Commission. The simplified method calculates the expected term as the average time-to-vesting and the contractual life of the options. For other option grants, the expected term is derived from the Company’s historical data on employee exercises and post-vesting employment termination behavior taking into account the contractual life of the award.
Expected Volatility — The expected stock price volatility assumption was determined by examining the historical volatilities of a group of industry peers and the Company’s own historical volatility since the Company began trading subsequent to its IPO in July 2012.
Risk-Free Interest Rate — The risk free rate assumption is based on U.S. Treasury instruments for which the terms were consistent with the expected term of the Company’s stock options.
Expected Dividend — The expected dividend assumption is based on the Company’s history and expectation of dividend payouts.
Forfeiture Rate — ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures were estimated based on historical experience.
Fair Value of Common Stock — Prior to the IPO, the fair value of the shares of common stock underlying the stock options has historically been the responsibility of and determined by the Company’s board of directors. Because there was no public market for the Company’s common stock, the board of directors determined fair value of common stock at the time of grant of the option by considering a number of objective and subjective factors including independent third-party valuations of the Company’s common stock, sales of convertible preferred stock to unrelated third parties, operating and financial performance, the lack of liquidity of capital stock and general and industry specific economic outlook, amongst other factors. Subsequent to the IPO, the fair value of the shares of the common stock underlying the stock options is the closing price on the option grant date.
Total stock-based compensation expense related to options and awards granted was allocated as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
Cost of sales		$	27		$	—		$	—
Research and development			585			374			137
Selling general and administrative			3,709			619			208
Total		$	4,321		$	993		$	345
For the year ended December 31, 2013, stock-based compensation of $82,000 was capitalized into inventories. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold. Allocations to research and development, general and administrative and selling and marketing expense are based upon the department to which the associated employee reported. No related tax benefits of the stock-based compensation expense have been recognized.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	17	Income Taxes
	For the year ended December 31, 2013, the Company generated a pretax income of $16.7 million in the U.S. For the years ended December 31, 2012 and 2011, the Company generated a pretax loss of $32.3 million and $29.4 million, respectively in the U.S. Since inception, the Company has not generated any pretax income or loss outside the U.S.
	The components of the income tax expense are as follows (in thousands):
			Years ended
			December 31,
			2013			2012			2011
	Current income tax expense:
	State		$	326		$	—		$	—
				326			—			—
	Deferred income tax benefit:
	State			(277	)		—			—
				(277	)		—			—
	Total income tax expense		$	49		$	—		$	—
	The reconciliation of income tax expense computed at the statutory federal income tax rate of 35% to amounts included in the consolidated statements of operations is as follows:
			Year Ended December 31,
			2013			2012			2011
	Statutory rate			35	%		34	%		34	%
	State tax			5.5	%		5.4	%		5.4	%
	Tax credits			(5.0	)%		0.7	%		24.8	%
	Stock options			0.2	%		(0.7	)%		(0.3	)%
	Valuation allowance			(29.6	)%		(37.1	)%		(60.1	)%
	Change in federal tax rate			(6.0	)%		—			—
	Other			0.2	%		(2.3	)%		(3.8	)%
				0.3	%		0	%		0	%
	The federal statutory rate increased from 34% to 35% in 2013 as this is the rate expected to be in place when deferred taxes reverse.
	Deferred income tax assets and liabilities reflect the net tax effects of net operating loss and tax credit carryovers and the temporary differences between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company’s deferred income tax assets are as follows (in thousands):
			Year Ended December 31,
			2013			2012
	Deferred income tax assets
	Fixed assets, capitalized intangibles and other assets		$	5,294		$	5,335
	Net operating loss			31,842			39,616
	Tax credits			18,480			16,907
	Stock-based compensation expense			1,133			178
	Other			1,527			869
	Total			58,276			62,905
	Valuation allowance			(58,000	)		(62,905	)
	Net deferred income tax assets		$	276		$	—
	At December 31, 2013, current deferred income tax asset of $0.1 million is included in “Prepaid expenses and other current assets” and the non-current deferred income tax asset of $0.2 million is included in “Other non-current assets” in the consolidated balance sheets.
	The amounts recorded as deferred income tax assets as of December 31, 2013 represent the amount of tax benefits of existing deductible temporary differences and carryforwards that are more likely than not to be realized through the generation of sufficient future taxable income within the carryforward period. For the year ended December 31, 2012, the federal and California deferred income tax assets have been fully offset by a valuation allowance. For the year ended December 31, 2013, the valuation allowance on deferred income tax asset reduced by $4.9 million. In addition, the amount of the valuation allowance for deferred tax assets associated with excess tax deductions from stock-based compensation arrangements that is allocated to contributed capital if the future tax benefits are subsequently recognized is $1.3 million. For the year ended December 31, 2012 and 2011, the increase in the valuation allowance on the deferred income tax assets was $12.0 and $17.7 million, respectively.
	At December 31, 2013, the Company had net operating loss carryforwards of approximately $72.5 million and $112.5 million available to reduce future taxable income, if any, for both federal and California state income tax purposes, respectively. The net operating loss carryforwards will begin to expire in 2026 for federal and 2016 for state purposes. If the Company experiences an “ownership change” for purposes of Section 382 of the Internal Revenue Code of 1986, as amended, it may be subject to annual limits on its ability to utilize net operating loss carryforwards and credits. An ownership change is, as a general matter, triggered by sales or acquisitions of its stock in excess of 50% on a cumulative basis during a three-year period by persons owning 5% or more of our total equity value. The Company is not currently subject to any annual limits on its ability to utilize net operating loss carryforwards and credits. The Company also had federal and state research and development credit carryforwards of approximately $18.0 million and $0.8 million respectively, at December 31, 2013. The federal credits will expire starting in 2027, if not utilized. The California credits have no expiration date.
	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. Included in the $18.0 million of federal credit carryforwards is $17.4 million of Orphan Drug Credit claims for 2009 through 2013.
	A reconciliation of the beginning and ending balances of the unrecognized income tax benefits during the years ended December 31, 2013, 2012 and 2011 is as follows (in thousands):
			Year Ended December 31,
			2013			2012			2011
	Balance at the beginning of the year		$	5,723		$	5,357		$	625
	Changes based on prior period tax positions			—			(228	)		2,839
	Changes based on current period tax positions			546			594			1,893
	Balance at the end of the year		$	6,269		$	5,723		$	5,357
	The entire amount of the unrecognized income tax benefits would not impact the Company’s effective tax rate if recognized.
	There was no interest or penalties accrued through December 31, 2013. 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 U.S. and California. The Company is not currently under income tax examinations by any tax authorities in federal, state or other jurisdictions.

Defined_Contribution_Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2013
Postemployment Benefits [Abstract]	'
Defined Contribution Plan	'
	18	Defined Contribution Plan
	The Company sponsors a defined contribution plan under Section 401(k) of the Internal Revenue Code (“Plan”) covering substantially all full-time U.S. employees. Employee contributions are voluntary and are determined on an individual basis subject to the maximum allowable under federal tax regulations. Participants are always fully vested in their contributions. For the year ended December 31, 2013, the Company made a contribution of $0.2 million to the Plan. For the year ended December 31, 2012, the Company did not make any contributions to the Plan.

Net_Income_Loss_per_Share_of_C

Net Income (Loss) per Share of Common Stock	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Net Income (Loss) per Share of Common Stock	'
	19	Net Income (Loss) per Share of Common Stock
	The following table sets forth the computation of basic and diluted net income (loss) per share of common stock for the periods indicated (in thousands, except share and per share amounts):
			Year Ended December 31,
			2013		2012			2011
	Net income (loss) per share
	Numerator:
	Net income (loss) attributable to common stockholders		$	16,627	$	(32,263	)	$	(29,416	)
	Denominator:
	Weighted-average number of common shares outstanding — basic			19,415,822		7,256,537			469,319
	Dilutive effect of stock-options and awards			1,315,091		—			—
	Weighted average common shares outstanding — dilutive			20,730,913		7,256,537			469,319
	Net income (loss) per share:
	Basic		$	0.86	$	(4.45	)	$	(62.68	)
	Diluted		$	0.8	$	(4.45	)	$	(62.68	)
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income (loss) per share, as the effect of including them would have been antidilutive:
			Year Ended December 31,
			2013		2012			2011
	Convertible preferred stock			—		—			6,575,637
	Stock options			1,027,605		1,928,754			1,279,240
	Common and preferred stock warrants			274		84,656			331,776
	Total			1,027,879		2,013,410			8,186,653

Related_Party_Transaction

Related Party Transaction	12 Months Ended
	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Related Party Transaction	'
	20	Related Party Transaction
	As part of the Company’s acquisition of BUPHENYL (see Note 4), the Company assumed the existing BUPHENYL distributors 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 the Middle East. SOBI’s chairman, Bo Jesper Hansen, is a member of the Company’s Board of Directors. During 2013, the Company recognized $2.2 million from sales to SOBI. As of December 31, 2013, the accounts receivable from SOBI amounted to $0.7 million.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Selected Quarterly Financial Data	'
	21	Selected Quarterly Financial Data (Unaudited)
	The following table presents selected unaudited quarterly financial information for the years ended December 31, 2013 and 2012. The results for any quarter are not necessarily indicative of future quarterly results and, accordingly, period to period comparisons should not be relied upon as an indication of future performance.
			For The Quarters Ended
	(in thousands, except share and per share amounts)		December 31,			September 30,			June 30,			March 31,
	Year Ended December 31, 2013
	Product revenue, net		$	18,627		$	15,489		$	7,305		$	783
	Costs and expenses		$	17,747		$	15,037		$	12,986		$	9,851
	Net income (loss) attributable to common stockholders		$	468		$	112		$	25,022		$	(8,975	)
	Net income (loss) per share attributable to common stockholders — basic		$	0.02		$	0.01		$	1.25		$	(0.52	)
	Net income (loss) per share attributable to common stockholders — diluted		$	0.02		$	0.01		$	1.17		$	(0.52	)
			December 31,			September 30,			June 30,			March 31,
	Year Ended December 31, 2012
	Costs and expenses		$	7,795		$	4,758		$	4,755		$	11,225
	Net loss attributable to common stockholders		$	(8,285	)	$	(4,930	)	$	(7,162	)	$	(11,886	)
	Net loss per share attributable to common stockholders — basic and diluted		$	(0.50	)	$	(0.44	)	$	(15.26	)	$	(25.33	)

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Basis of Presentation and the Use of Estimates	'
	Basis of Presentation and the Use of Estimates
	The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of the accompanying 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 consolidated 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 the 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.
Basis of Consolidation	'
	Basis of Consolidation
	The consolidated financial statements include the accounts of the Company and Hyperion Therapeutics Limited. All intercompany balances and transactions, if any, have been eliminated for purposes of consolidation.
Reclassifications	'
	Reclassifications
	Certain prior year amounts in the consolidated financial statements have been reclassified to conform to the current year’s presentation. In particular, sales and marketing expenses have been combined with general and administrative expenses in the consolidated statements of operations. The result of this reclassification had no impact on the previously reported net loss, the consolidated balance sheets or the consolidated statements of cash flows.
Segment Reporting	'
	Segment Reporting
	The Company operates as one operating segment and uses one measurement of profitability to manage its business. All long-lived assets are maintained in the United States. For the year ended December 31, 2013, net product revenue in the United States and rest of the world (primarily Canada and Europe) was $37.0 million and $5.2 million, respectively. For the year ended December 31, 2013, net product revenue consisted of net sales from RAVICTI of $31.2 million and net sales from BUPHENYL of $11.5 million partially offset by $0.5 million of co-payment assistance.
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 December 31, 2013, 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 consist of raw materials and finished goods. Costs 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 consolidated statements of operations. If information becomes available that suggest that inventories may not be realizable, the Company may be required to expense a portion or all of the previously capitalized inventories.
	Products that have been approved by the FDA or other regulatory authorities, such as RAVICTI are also used in clinical programs, to assess the safety and efficacy of the products for usage in diseases that have not been approved by the FDA or other regulatory authorities. The form of RAVICTI utilized for both commercial and clinical programs is identical and, as a result, the inventory has an “alternative future use” as defined in authoritative guidance. Raw materials and purchased drug product associated with clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes and, therefore, does not have an “alternative future use”.
	On May 31, 2013, the Company acquired BUPHENYL from Ucyclyd (see Note 4). The Company recorded the acquired BUPHENYL inventories at fair value in the amount of $3.9 million on the acquisition date. The Company is expensing the difference between the fair value and book value of inventory as that inventory is sold.
Business Combinations	'
	Business Combinations
	The Company allocates the purchase price of an acquired business to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. Any excess of the purchase price over the fair value of the net assets acquired is recorded as goodwill. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets. Direct transaction costs associated with the business combination are expensed as incurred.
Intangible Assets	'
	Intangible Assets
	Intangible assets are recorded at acquisition cost less accumulated amortization and impairment. Intangible assets with finite lives are amortized over their estimated useful lives. The Company’s intangible asset pertains to BUPHENYL product rights (see Note 4). The intangible asset is amortized over the estimated useful life using the economic use method, which reflects the pattern that the economic benefits of the intangible asset are consumed as revenue is generated. The pattern of consumption of the economic benefits is estimated using the future projected cash flows of the intangible asset.
Impairment of Long-lived Assets	'
	Impairment of Long-lived Assets
	The Company reviews its property and equipment, intangible assets subject to amortization and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset group 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.
Property and Equipment	'
	Property and Equipment
	Property and equipment are stated at cost, net of accumulated depreciation and amortization. All property and equipment is depreciated on a straight-line basis over the following estimated useful lives:
	Computer and office equipment		3 – 5 years
	Software		3 years
	Furniture and fixtures		3 years
	Leasehold improvements are amortized over the lesser of their useful life or the term of the applicable lease. Upon sale or retirement of assets, the cost and related accumulated depreciation and amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in operations. Maintenance and repairs are charged to operations as incurred.
2012 Reverse Stock Split	'
	2012 Reverse Stock Split
	The Company effected a 1-for-6.09 reverse stock split of its common stock and preferred stock on July 12, 2012. Accordingly, all share and per share amounts for all periods presented in these consolidated financial statements and notes thereto, have been adjusted retroactively to reflect this reverse stock split.
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. In 2013 there were no credit losses on the Company’s accounts receivable. As at December 31, 2013, the specialty distributor in the United States accounted for 64% of the accounts receivable balance and one international distributor accounted for 17% of the accounts receivable balance.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	The Company measures certain financial assets and liabilities at fair value based on the exchange price that would be received for an asset or paid for to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. The carrying amounts of the Company’s financial instruments, including cash equivalents, short-term investments, the option to purchase BUPHENYL and AMMONUL, accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of long-term investments represent their estimated fair values. The Company’s debt obligations are carried at historical cost, which approximates fair value.
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.
Warrants Liability	'
	Warrants Liability
	The Company accounts for its warrants and other derivative financial instruments as either equity or liabilities based upon the characteristics and provisions of each instrument. Warrants classified as equity are recorded as additional paid-in capital on the consolidated balance sheets and no further adjustments to their valuation are made. Warrants classified as derivative liabilities and other derivative financial instruments that require separate accounting as liabilities are recorded on the Company’s consolidated balance sheets at their fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized as increases or reductions to other income (expense), net in the consolidated statements of operations.
Revenue Recognition	'
	Revenue Recognition
	The Company recognizes revenue in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, Revenue Recognition, when the following criteria have been met: persuasive evidence of an arrangement exists; delivery has occurred and risk of loss has passed; the seller’s price to the buyer is fixed or determinable and collectability is reasonably assured. The Company determines that persuasive evidence of an arrangement exists based on written contracts that defined the terms of the arrangements. In addition, the Company determines that services have been delivered in accordance with the arrangement. The Company assesses whether the fee is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. The Company assesses collectability based primarily on the customer’s payment history and on the creditworthiness of the customer.
	Product Revenue, net: The Company’s product revenue represents sales of RAVICTI and BUPHENYL which are recognized once all four revenue recognition criteria described above are met. The Company recognizes revenue net of product sales allowances. Product shipping and handling costs are included in cost of sales.
		•	During 2013, the Company began distributing RAVICTI to two specialty pharmacies through a specialty distributor. The specialty pharmacies then in turn dispensed RAVICTI to patients in fulfillment of prescriptions. As RAVICTI is a new product, and the Company’s first commercial product, the Company could not reasonably assess potential product sales allowances at the time of sale to the specialty distributor. As a result, the price of RAVICTI was not deemed fixed or determinable. The Company does not record revenue on shipments of RAVICTI to the specialty distributor, until the product was shipped to patients by the specialty pharmacies at which time the related product sales allowances could be reasonably estimated.
		•	As discussed in Note 4, on May 31, 2013, the Company acquired BUPHENYL from Ucyclyd. The Company sells BUPHENYL in the United States to a specialty distributor who in turn sells this product to retail pharmacies, hospitals and other dispensing organizations. The Company records revenue on product shipments to the specialty distributor upon receipt by the specialty distributor. For product sales of BUPHENYL outside the United States, revenue is recognized once the product is accepted by the customer or their acceptance period has expired, whichever comes first.
	Product Sales Allowances: The Company establishes reserves for prompt-payment discounts, government and commercial rebates, product returns and chargebacks. Allowances related to prompt-payment discounts 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 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 distributor, two specialty pharmacies and our dedicated call center. 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 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 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 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 consolidated balance sheet.
	Co-payment assistance: The Company provides a cash donation to a non-profit third party organization which supports UCD 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. Cost of BUPHENYL sales as a percentage of revenue was higher and not indicative of cost of sales in future periods due to the recording of the step-up value on BUPHENYL inventories acquired from Ucyclyd which is expensed to cost of sales as that inventory is sold. (See Note 4)
Foreign Currency Translations	'
	Foreign Currency Translations
	The Company has cash and accounts receivable denominated in foreign currency are translated at the rate of exchange in effect on the balance sheet date. Revenue and expenses denominated in foreign currency are translated at the weighted average rate of exchange prevailing during the period. Any gains and losses resulting from foreign currency translations are included in other income (expense)-net in the consolidated statements of operations.
Research and Development Expenses	'
	Research and Development Expenses
	Costs related to research and development of products are charged to expense as incurred. Research and development costs include, but are not limited to, payroll and personnel expenses, clinical trial supplies, fees for clinical trial services, consulting costs and allocated overhead, including rent, equipment, depreciation and utilities.
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.
Comprehensive Income (Loss)	'
	Comprehensive Income (Loss)
	Comprehensive income (loss) is comprised of net income (loss) and other comprehensive loss. Other comprehensive loss includes changes in stockholders’ equity that are excluded from net income (loss), specifically changes in unrealized gains and losses on the Company’s available-for-sale securities.
Net Income (Loss) per Share of Common Stock	'
	Net Income (Loss) per Share of Common Stock
	Basic earnings per share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during the periods presented. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and other potentially dilutive securities using the treasury stock method, unless the effect is antidilutive.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In February 2013, FASB issued Accounting Standard Update (“ASU”) No. 2013-02, Comprehensive Income: Reporting of amounts reclassified out of other comprehensive income. Under the amendments of this update an entity is required to present either parenthetically on the face of the financial statements or in the notes, significant amounts reclassified from each component of accumulated other comprehensive income and the income statement line items affected by the reclassification. However, an entity would not need to show the income statement line item affected for certain components that are not required to be reclassified in their entirety to net income, such as amounts amortized into net periodic pension cost. The standard was effective prospectively for public entities for fiscal years, and interim periods with those years, beginning after December 15, 2012. Early adoption was permitted. The Company adopted this guidance on January 1, 2013. The implementation did not have an impact on the Company’s consolidated financial statements.
	In July 2013, FASB issued ASU No. 2013-11, Income Taxes (Topic 740): Presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. Under the amendments of this update an entity is required to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except as follows. To the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes that would result from the disallowance of a tax position or the tax law of the applicable jurisdiction does not require the entity to use, and the entity does not intend to use, the deferred tax asset for such purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The assessment of whether a deferred tax asset is available is based on the unrecognized tax benefit and deferred tax asset that exist at the reporting date and should be made presuming disallowance of the tax position at the reporting date. For example, an entity should not evaluate whether the deferred tax asset expires before the statute of limitations on the tax position or whether the deferred tax asset may be used prior to the unrecognized tax benefits being settled. The provisions of this update will be effective prospectively for the Company in fiscal years beginning after December 15, 2013, and for the interim periods within fiscal years with early adoption and retrospective application permitted. The Company believes the adoption of this new guidance will not have a material impact on its consolidated financial statements.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Schedule of Property and Equipment Estimated Useful Lives	'
	All property and equipment is depreciated on a straight-line basis over the following estimated useful lives:
	Computer and office equipment	3 – 5 years
	Software	3 years
	Furniture and fixtures	3 years

Acquisition_of_BUPHENYL_from_U1

Acquisition of BUPHENYL from Ucyclyd Pharma, Inc. (Tables)	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Schedule of Purchase Price Allocation	'
	The following table summarizes the allocation of purchase price to the fair values of the assets acquired as of the acquisition date:
			(in thousands)
	Inventories		$	3,900
	Intangible Asset — BUPHENYL Product rights			16,500
	Total		$	20,400
Total Gain from Buphenyl Acquisition	'
	The following table summarizes the results of the Company’s allocation:
			(in thousands)
	Ucyclyd’s retention option amount		$	32,000
	Amount due to Ucyclyd for BUPHENYL product rights			(19,000	)
	Amount due to Ucyclyd for inventory			(2,038	)
	Net payment received from Ucyclyd			10,962
	Option to purchase the rights to BUPHENYL and AMMONUL			(283	)
	Fair value of BUPHENYL			20,400
	Gain from settlement of retention option		$	31,079
Consolidated Pro Forma Information	'
	The following consolidated pro forma information is based on the assumption that the acquisition occurred on January 1, 2012. The unaudited pro forma information is presented for comparative purposes only and is not necessarily indicative of the financial position or results of operations which would have been reported had the Company completed the acquisition during these periods or which might be reported in the future. The unaudited pro forma information reflects primarily the application of the following adjustments:
		•		the elimination of the historical intangible asset amortization expense of this acquisition;
		•		the amortization expense related to the fair value of intangible asset acquired;
		•		the exclusion of acquisition-related costs, incurred for this acquisition; and
		•		the exclusion of the step-up value related to inventory sold that was acquired as part of the acquisition.
	The unaudited pro forma information is not necessarily indicative of what the Company’s consolidated results of operations actually would have been had the acquisition been completed on January 1, 2012. In addition, the unaudited pro forma information does not purport to project the future results of operations of the Company.
			Year Ended
			December 31,
			2013			2012
			( in thousands)
	Net revenues		$	52,900		$	21,501
	Net income (loss)			24,266			(28,976	)

Investments_Tables

Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
Schedule of Investments by Contractual Maturity	'
	The principal amounts of investments by contractual maturity are summarized in the tables below:
		Contractual Maturity Date for the					Total Book		Unrealized			Aggregate
		Years Ending December  31,					Value at		Loss			Fair Value at
							December 31, 2013					December 31, 2013
		2014		2015
	Certificates of deposit	$	10,525	$	2,845		$	13,370	$	(27	)	$	13,343
	Corporate notes		6,047		12,960			19,007		(24	)		18,983
	U.S. Government agency securities		8,011		—			8,011		(3	)		8,008
	Commercial paper		3,492		—			3,492		(1	)		3,491
	Total	$	28,075	$	15,805		$	43,880	$	(55	)	$	43,825
Schedule of Unrealized Losses and Related Fair Value of Investments with Unrealized Losses	'
	The aggregate amounts of unrealized losses and related fair value of investments with unrealized losses as of December 31, 2013 was as follows:
		Less Than 12 Months to					12 Months or More to					Total
		Maturity					Maturity
		Aggregate		Unrealized			Aggregate		Unrealized			Aggregate		Unrealized
		Fair Value		Losses			Fair Value		Losses			Fair Value		Losses
	Certificates of deposit	$	10,507	$	(18	)	$	2,836	$	(9	)	$	13,343	$	(27	)
	Corporate notes		6,039		(8	)		12,944		(16	)		18,983		(24	)
	U.S. Government agency securities		8,008		(3	)		—		—			8,008		(3	)
	Commercial paper		3,491		(1	)		—		—			3,491		(1	)
	Total	$	28,045	$	(30	)	$	15,780	$	(25	)	$	43,825	$	(55	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2013
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 December 31, 2013 and 2012 (in thousands):
		Fair Value Measurements at December 31, 2013
		Quoted Price in		Significant Other		Significant		Total
		Active Markets		Observable Inputs		Unobservable
		for Identical Assets		(Level 2)		Inputs
		(Level 1)				(Level 3)
	Assets:
	Cash equivalents:
	Money market funds	$	38,506	$	—	$	—	$	38,506
	Certificates of deposit		—		480		—		480
	Total cash equivalents	$	38,506	$	480	$	—	$	38,986
	Available-for-sale securities:
	Short-term:
	Certificates of deposit	$	—	$	10,507	$	—	$	10,507
	Commercial paper		—		3,491		—		3,491
	Corporate notes		—		6,039		—		6,039
	U.S. Government agency securities		—		8,008		—		8,008
	Total short-term investments		—		28,045		—		28,045
	Long-term:
	Certificates of deposit		—		2,836		—		2,836
	Corporate notes		—		12,944		—		12,944
	Total long-term investments		—		15,780		—		15,780
	Total available-for-sale securities	$	—	$	43,825	$	—	$	43,825
		December 31, 2012
		Quoted prices in		Significant Other		Significant
		Active Markets		Observable		Unobservable
		for Identical		Inputs (Level 2)		Inputs
		Items (Level 1)				(Level 3)
	Assets:
	Cash and cash equivalents:
	Money market funds	$	45,003	$	—	$	—
		$	45,003	$	—	$	—
Carrying Value and Estimated Fair Value of Company's Notes Payable	'
	The following table presents the carrying value and estimated fair value of the Company’s notes payable as of December 31, 2013 (in thousands):
		December 31, 2013
		Carrying		Estimated
		Value		Fair Value
	April and September 2012 Notes	$	8,273	$	8,860

Inventories_Tables

Inventories (Tables)	12 Months Ended
	Dec. 31, 2013
Inventory Disclosure [Abstract]	'
Components of Inventories	'
	The following table represents the components of inventories (in thousands):
		December 31,		December 31,
		2013		2012
	Raw Materials	$	697	$	—
	Finished goods		2,816		—
	Total	$	3,513	$	—

Intangible_Asset_Tables

Intangible Asset (Tables)	12 Months Ended
	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Schedule of Expected Amortization Expense	'
	Estimated aggregate amortization expense for each of the five succeeding years ending December 31 is as follows (in thousands):
		2014		2015		2016		2017		2018
	Amortization expense	$	4,053	$	3,294	$	1,157	$	1,048	$	1,012

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Components of Property and Equipment	'
	The following table represents the components of property and equipment (in thousands):
		December 31,			December 31,
		2013			2012
	Computers and Software	$	563		$	95
	Furniture and Fixtures		320			—
	Office Equipment		53			21
	Leasehold Improvements		—			247
	Capital work in progress		264			—
			1,200			363
	Less: Accumulated depreciation		(264	)		(314	)
	Total property and equipment, net	$	936		$	49

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2013
Payables And Accruals [Abstract]	'
Components of Accrued Liabilities	'
	The following table represents the components of accrued liabilities (in thousands):
		December 31,
		2013		2012
	Preclinical and clinical trial expenses	$	246	$	583
	Payroll and related expenses		4,278		1,457
	Gross to net sales accruals		5,235		—
	Royalty payable		1,154		—
	State taxes payable		326		—
	Interest payable		61		93
	Other		887		407
		$	12,187	$	2,540

Notes_Payable_Tables

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Future Minimum Payments Under April Twenty Twelve and September Twenty Twelve Notes	'
	Future minimum payments under the April 2012 and September 2012 Notes as of December 31, 2013 are as follows (in thousands):
	Years Ending December 31,
	2014	$	6,152
	2015		3,376
	Total future minimum payments	$	9,528
	Less: amount representing unamortized interest		(563	)
	Less: amount representing debt discount		(692	)
	Total minimum payments	$	8,273
	Less: current portion		(5,652	)
	Non-current portion	$	2,621

Warrants_Tables

Warrants (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Summary of Outstanding Warrants and Corresponding Exercise Price	'
	The following table summarizes the outstanding warrants and the corresponding exercise price as of December 31, 2013 and 2012:
		Number of Shares				Per Share
		Outstanding				Exercise Price
		December 31,
		2013		2012
	October 2007 common stock warrants		274		274	$	1,913.05
	April 2012 common stock warrants		—		75,974		4.08
	September 2012 common stock warrants		—		8,408		5.05
	Total		274		84,656

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Future Minimum Lease Payments	'
	Aggregate total future minimum lease payments under operating facility and equipment leases as of December 31, 2013 were as follows (in thousands):
	Years Ending December 31,
	2014	$	518
	2015		797
	2016		820
	2017		821
	2018		845
	Thereafter		766
	Total	$	4,567

Common_Stock_Tables

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Common Stock Reserved for Future Issuances	'
	At December 31, 2013, the Company had reserved common stock for future issuances as follows:
	Issuance of options under 2012 stock plan	576,760
	Issuance upon exercise of options under the 2006 and 2012 stock plan	2,790,629
	Issuance upon vesting of restricted stock awards under the 2012 stock plan	18,000
	Issuance upon exercise of common stock warrants	274
	Total	3,385,663

Stock_Option_Plan_Tables

Stock Option Plan (Tables)	12 Months Ended
	Dec. 31, 2013
Aggregate Options Outstanding and Vested and Exercisable by Exercise Price	'
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2013 for the 2006 plan are as follows (dollars in thousands except per share values):
	Options Outstanding										Options Vested and Exercisable
	Exercise	Number			Aggregate			Weighted			Number			Aggregate		Exercise
	Price	Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
					Value			Remaining						Value
								Life (in Years)
	$    1.28		821,322		$	15,556			5.9			820,056		$	15,532	$	1.28
	$    4.08		305,873			4,937			7.3			209,603			3,383	$	4.08
	$    7.31		410,061			5,294			8.3			228,207			2,946	$	7.31
	$    327.95		940			—			4			940			—	$	327.95
			1,538,196		$	25,787			6.8			1,258,806		$	21,861
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2012 are as follows (dollars in thousands except per share values):
	Options Outstanding										Options Vested and Exercisable
	Exercise	Number			Aggregate			Weighted			Number			Aggregate		Exercise
	Price	Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
					Value			Remaining						Value
								Life (in Years)
	$1.28		836,292		$	8,363			6.9			814,675		$	8,147	$	1.28
	$4.08		373,037			2,686			8.3			153,564			1,106	$	4.08
	$7.31		451,253			1,791			9.3			75,201			299		7.31
	$327.95		940			—			5			940			—	$	327.95
			1,661,522		$	12,840			7.9			1,044,380		$	9,552
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2013 for the 2012 plan are as follows (dollars in thousands except per share values):
		Options Outstanding									Options Vested and Exercisable
	Exercise Price	Number			Aggregate			Weighted			Number			Aggregate		Exercise
		Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
					Value			Remaining						Value
								Life (in Years)
	$10.32- 11.28		225,768		$	2,183			8.8			86,531		$	837	$	10.32 - 11.28
	$18.24- 19.39		188,000			257			9.1			—			—		18.24 - 19.39
	$20.07- 21.45		121,625			4			9.5			—			—		20.07 - 21.45
	$22.00- 22.06		86,200			—			9.5			—			—		22.00 - 22.06
	$24.38- 24.94		536,140			—			9.3			—			—		24.38 - 24.94
	$25.05- 26.50		94,700			—			9.5			—			—		25.05 - 26.50
			1,252,433		$	2,444			9.2			86,531		$	837
	Aggregate options outstanding and vested and exercisable by exercise price at December 31, 2012 for the 2012 plan are as follows (dollars in thousands except per share values):
		Options Outstanding									Options Vested and Exercisable
	Exercise Price	Number			Aggregate			Weighted			Number			Aggregate		Exercise
		Outstanding			Intrinsic			Average			Outstanding			Intrinsic		Price
					Value			Remaining						Value
								Life (in Years)
	$10.32		20,000		$	19			9.7			1,666		$	2	$	10.32
	$10.33		117,732			112			9.6			—			—		—
	$10.61		69,500			47			10			—			—		—
	$10.95		15,000			5			9.8			625			0.2	$	10.95
	$11.28		45,000			—			10			—			—		—
			267,232		$	183			9.8			2,291		$	2.2
Weighted-Average Assumptions for Fair Value of Stock Options	'
	The fair value of the employee stock options was estimated using the following weighted-average assumptions:
		Year Ended December 31,
		2013			2012			2011
	Expected volatility		58	%		65	%		62	%
	Risk-free interest rate		1.14	%		1.05	%		2.48	%
	Dividend yield		0	%		0	%		0	%
	Expected term (in years)		5.96			6			6.01
Allocation of Stock-Based Compensation Expense	'
	Total stock-based compensation expense related to options and awards granted was allocated as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Cost of sales	$	27		$	—		$	—
	Research and development		585			374			137
	Selling general and administrative		3,709			619			208
	Total	$	4,321		$	993		$	345
2006 Plan	'
Schedule of Option Activity	'
	Activity under the 2006 Plan is as follows:
					Outstanding Options
		Number of Shares			Number of Shares			Weighted-Average
		Available for			Underlying			Exercise Price  Per
		Grant			Outstanding			Share
					Options
	Balances at December 31, 2012		—			1,661,522			3.73
	Options exercised		—			(100,280	)		4.62
	Options cancelled		23,046			(23,046	)		5.68
	Options re-allocated to 2012 Plan		(23,046	)		—			—
	Balances at December 31, 2013		—			1,538,196		$	3.64
2012 Plan	'
Schedule of Option Activity	'
	Activity under the 2012 Plan is as follows:
					Outstanding Options						Restricted Stock Units
											Outstanding
		Number of Shares			Number of Shares			Weighted-Average			Number of Shares			Grant
		Available for			Underlying			Exercise Price  Per			Underlying			Date
		Grant			Outstanding			Share			Outstanding			Fair Value
					Options						RSU’s
	Balances at December 31, 2012		907,908			267,232			10.6			—			—
	Additional shares authorized		665,850			—			—			—			—
	Options and awards granted		(1,088,315	)		1,067,315			22.9			21,000			19.39
	Options exercised		—			(16,843	)		10.33			—			—
	Options re-allocated to 2012 Plan		23,046			—			—			—			—
	Options and awards cancelled		68,271			(65,271	)		17.01			(3,000	)		—
	Balance at December 31, 2013		576,760			1,252,433		$	20.75			18,000		$	19.39

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Components of Income Tax Expense	'
	The components of the income tax expense are as follows (in thousands):
		Years ended
		December 31,
		2013			2012			2011
	Current income tax expense:
	State	$	326		$	—		$	—
			326			—			—
	Deferred income tax benefit:
	State		(277	)		—			—
			(277	)		—			—
	Total income tax expense	$	49		$	—		$	—
Reconciliation of Income Tax Expense	'
	The reconciliation of income tax expense computed at the statutory federal income tax rate of 35% to amounts included in the consolidated statements of operations is as follows:
		Year Ended December 31,
		2013			2012			2011
	Statutory rate		35	%		34	%		34	%
	State tax		5.5	%		5.4	%		5.4	%
	Tax credits		(5.0	)%		0.7	%		24.8	%
	Stock options		0.2	%		(0.7	)%		(0.3	)%
	Valuation allowance		(29.6	)%		(37.1	)%		(60.1	)%
	Change in federal tax rate		(6.0	)%		—			—
	Other		0.2	%		(2.3	)%		(3.8	)%
			0.3	%		0	%		0	%
Components of Deferred Income Tax Assets	'
	Significant components of the Company’s deferred income tax assets are as follows (in thousands):
		Year Ended December 31,
		2013			2012
	Deferred income tax assets
	Fixed assets, capitalized intangibles and other assets	$	5,294		$	5,335
	Net operating loss		31,842			39,616
	Tax credits		18,480			16,907
	Stock-based compensation expense		1,133			178
	Other		1,527			869
	Total		58,276			62,905
	Valuation allowance		(58,000	)		(62,905	)
	Net deferred income tax assets	$	276		$	—
Reconciliation of Beginning and Ending Balances of Unrecognized Income Tax Benefits	'
	A reconciliation of the beginning and ending balances of the unrecognized income tax benefits during the years ended December 31, 2013, 2012 and 2011 is as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Balance at the beginning of the year	$	5,723		$	5,357		$	625
	Changes based on prior period tax positions		—			(228	)		2,839
	Changes based on current period tax positions		546			594			1,893
	Balance at the end of the year	$	6,269		$	5,723		$	5,357

Net_Income_Loss_per_Share_of_C1

Net Income (Loss) per Share of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Net Income (Loss) Per Share of Common Stock	'
	The following table sets forth the computation of basic and diluted net income (loss) per share of common stock for the periods indicated (in thousands, except share and per share amounts):
		Year Ended December 31,
		2013		2012			2011
	Net income (loss) per share
	Numerator:
	Net income (loss) attributable to common stockholders	$	16,627	$	(32,263	)	$	(29,416	)
	Denominator:
	Weighted-average number of common shares outstanding — basic		19,415,822		7,256,537			469,319
	Dilutive effect of stock-options and awards		1,315,091		—			—
	Weighted average common shares outstanding — dilutive		20,730,913		7,256,537			469,319
	Net income (loss) per share:
	Basic	$	0.86	$	(4.45	)	$	(62.68	)
	Diluted	$	0.8	$	(4.45	)	$	(62.68	)
Antidilutive Securities Excluded from Computation of Earnings Per Share	'
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income (loss) per share, as the effect of including them would have been antidilutive:
		Year Ended December 31,
		2013		2012			2011
	Convertible preferred stock		—		—			6,575,637
	Stock options		1,027,605		1,928,754			1,279,240
	Common and preferred stock warrants		274		84,656			331,776
	Total		1,027,879		2,013,410			8,186,653

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Selected Unaudited Quarterly Financial Information	'
	The following table presents selected unaudited quarterly financial information for the years ended December 31, 2013 and 2012. The results for any quarter are not necessarily indicative of future quarterly results and, accordingly, period to period comparisons should not be relied upon as an indication of future performance.
		For The Quarters Ended
	(in thousands, except share and per share amounts)	December 31,			September 30,			June 30,			March 31,
	Year Ended December 31, 2013
	Product revenue, net	$	18,627		$	15,489		$	7,305		$	783
	Costs and expenses	$	17,747		$	15,037		$	12,986		$	9,851
	Net income (loss) attributable to common stockholders	$	468		$	112		$	25,022		$	(8,975	)
	Net income (loss) per share attributable to common stockholders — basic	$	0.02		$	0.01		$	1.25		$	(0.52	)
	Net income (loss) per share attributable to common stockholders — diluted	$	0.02		$	0.01		$	1.17		$	(0.52	)
		December 31,			September 30,			June 30,			March 31,
	Year Ended December 31, 2012
	Costs and expenses	$	7,795		$	4,758		$	4,755		$	11,225
	Net loss attributable to common stockholders	$	(8,285	)	$	(4,930	)	$	(7,162	)	$	(11,886	)
	Net loss per share attributable to common stockholders — basic and diluted	$	(0.50	)	$	(0.44	)	$	(15.26	)	$	(25.33	)

Formation_and_Business_of_Comp

Formation and Business of Company - Additional Information (Detail) (USD $)

0 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

Jul. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Aug. 14, 2013

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2011

Jul. 31, 2012

Jun. 30, 2009

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Mar. 13, 2013

April 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

Series C-1 Convertible Preferred Stock

Series C-2 Convertible Preferred Stock

Series C-2 Convertible Preferred Stock

April 2011 Common Stock Warrants Liability

October 2011 Preferred Stock Warrants Liability

Initial Public Offering

Follow-on offering

Nature Of Operations [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, shares issued

5,000,000

'

'

'

'

'

'

'

'

2,331,116

'

'

'

'

2,875,000

Offering price per share

$10

'

'

'

'

'

'

'

'

'

'

'

'

'

$20.75

Additional shares issued for over-allotment

750,000

'

'

'

'

'

'

'

'

'

'

'

'

'

431,250

Net proceeds from initial public offering

'

'

$53,475,000

'

'

'

'

'

'

'

'

'

'

$51,300,000

'

Underwriting discounts and commissions

'

4,116,000

4,025,000

'

'

'

'

'

'

'

'

'

'

4,025,000

4,116,000

Other offering expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

2,200,000

800,000

Preferred stock converted into common stock

'

'

'

'

'

'

'

'

1,912,598

'

4,663,039

'

'

'

'

Principal and accrued interest converted upon closing of IPO

'

'

'

'

'

18,900,000

15,600,000

15,600,000

'

'

'

'

'

'

'

Number of shares issued upon conversion of notes

'

'

'

'

'

1,888,054

1,556,816

1,556,816

'

'

'

'

'

'

'

Carrying value and accrued interest

'

'

'

'

'

18,400,000

14,900,000

14,900,000

'

'

'

'

'

'

'

Shares issued for conversion of warrants upon closing of IPO

'

'

'

'

'

'

'

'

'

'

'

322,599

17,762

'

'

Net proceeds from public offering

'

64,488,000

'

'

'

'

'

'

'

'

'

'

'

'

63,700,000

Aggregate offering price

'

'

'

'

150,000,000

'

'

'

'

'

'

'

'

'

'

Common stock shares sold by selling stockholders

'

'

'

'

8,727,000

'

'

'

'

'

'

'

'

'

'

Aggregate offering price under sales agreement

'

'

'

'

50,000,000

'

'

'

'

'

'

'

'

'

'

Income (loss) from operations

'

-13,417,000

-28,533,000

-26,159,000

'

'

'

'

'

'

'

'

'

'

'

Cash used in operations

'

-1,212,000

-28,531,000

-24,531,000

'

'

'

'

'

'

'

'

'

'

'

Accumulated deficit

'

($122,370,000)

($138,997,000)

'

'

'

'

'

'

'

'

'

'

'

'

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)

0 Months Ended

3 Months Ended

12 Months Ended

7 Months Ended

12 Months Ended

12 Months Ended

Jul. 12, 2012

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

31-May-13

Dec. 31, 2013

Store

Segment

United States

Canada and Europe

BUPHENYL

BUPHENYL

BUPHENYL

RAVICTI

Store

Summary Of Significant Accounting Policies [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Impact of reclassification of expenses on net loss

'

'

'

'

'

$0

'

'

'

'

'

'

Number of operating segments

'

'

'

'

'

1

'

'

'

'

'

'

Net product revenue

'

18,627,000

15,489,000

7,305,000

783,000

42,204,000

37,000,000

5,200,000

11,500,000

11,500,000

'

31,200,000

Net sales offset by co-payment assistance

'

'

'

'

'

'

'

'

'

500,000

'

'

Allowances for doubtful accounts

'

'

'

'

'

0

'

'

'

'

'

'

Acquisition of inventory

'

'

'

'

'

'

'

'

'

'

3,900,000

'

Reverse stock split

'1-for-6.09

'

'

'

'

'

'

'

'

'

'

'

Reverse stock split ratio

6.09

'

'

'

'

'

'

'

'

'

'

'

Credit losses on accounts receivable

'

0

'

'

'

0

'

'

'

'

'

'

Percentage of domestic accounts receivable

'

64.00%

'

'

'

64.00%

'

'

'

'

'

'

Percentage of accounts receivable by international distributor

'

17.00%

'

'

'

17.00%

'

'

'

'

'

'

Adjustments to accrued preclinical trail expenses

'

'

'

'

'

$0

'

'

'

'

'

'

Number of specialty pharmacies distributions made

'

2

'

'

'

2

'

'

'

'

'

'

Percentage of Medicare Part D insurance coverage gap to eligible patients

'

'

'

'

'

50.00%

'

'

'

'

'

'

Schedule_of_Property_and_Equip

Schedule of Property and Equipment Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2013
Software	'
Property Plant And Equipment Estimated Useful Lifes [Line Items]	'
Estimated useful lives	'3 years
Furniture and Fixtures	'
Property Plant And Equipment Estimated Useful Lifes [Line Items]	'
Estimated useful lives	'3 years
Minimum | Computer and Office Equipment	'
Property Plant And Equipment Estimated Useful Lifes [Line Items]	'
Estimated useful lives	'3 years
Maximum | Computer and Office Equipment	'
Property Plant And Equipment Estimated Useful Lifes [Line Items]	'
Estimated useful lives	'5 years

Collaboration_Agreement_with_U1

Collaboration Agreement with Ucyclyd Pharma, Inc. - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Option to purchase rights to BUPHENYL and AMMONUL	'	'	'	$283,000
Purchase option exercise period	'90 days	'	'	'
Purchase price for AMMONUL and BUPHENYL	22,000,000	'	'	'
Monthly payments	'	500,000	'	'
Purchase price to retain product rights	'	'	32,000,000	'
Net payment to be received for purchase transaction	'	'	11,000,000	'
Cash paid to Ucyclyd for BUPHENYL product rights	'	'	19,000,000	'
Cash due to Ucyclyd for inventory	'	'	2,038,000	'
Purchase agreement with Ucyclyd	'	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Payment under purchase agreement	6,000,000	'	'	'
Purchase agreement with Ucyclyd | RAVICTI	'	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Payment under purchase agreement	5,700,000	'	'	'
Purchase agreement with Ucyclyd | RAVICTI | Scenario One	'	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Maximum amount of regulatory milestones, product approval	15,800,000	'	'	'
Regulatory milestones, product approval, description	'	'	'Regulatory milestones related to approval of GPB in HE	'
Purchase agreement with Ucyclyd | RAVICTI | Scenario Two	'	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Regulatory milestones, product approval, description	'	'	'Regulatory milestones approval of GPB in indications other than UCD or HE	'
Maximum amount of regulatory milestones, approval in other indications	7,300,000	'	'	'
Purchase agreement with Ucyclyd | RAVICTI | Scenario Three	'	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Regulatory milestones, product approval, description	'	'	'Net sales milestones if GPB is approved for use in indications other than UCD (such as HE) and all annual sales targets are reached	'
Maximum amount of regulatory milestones, approval in other indications	38,800,000	'	'	'
Purchase agreement with Ucyclyd | BUPHENYL and AMMONUL	'	'	'	'
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'
Option to purchase rights to BUPHENYL and AMMONUL	'	'	'	$283,000

Acquisition_of_BUPHENYL_from_U2

Acquisition of BUPHENYL from Ucyclyd Pharma, Inc. - Additional Information (Detail) (USD $)	3 Months Ended				12 Months Ended	0 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2013	31-May-13	Dec. 31, 2013	Dec. 31, 2013
						BUPHENYL	BUPHENYL	BUPHENYL
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'
Business acquisition period results included in combined entity	$18,627,000	$15,489,000	$7,305,000	$783,000	$42,204,000	'	$11,500,000	$11,500,000
Acquisition date	'	'	'	'	31-May-13	'	'	'
Net cash received from Ucyclyd	'	'	'	'	'	11,000,000	'	'
Cash paid to Ucyclyd for BUPHENYL product rights	'	'	'	'	19,000,000	19,000,000	'	'
Cash due to Ucyclyd for inventory	'	'	'	'	2,038,000	2,038,000	'	'
Ucyclyd's retention option amount	'	'	'	'	'	32,000,000	'	'
Expected useful life of acquired product rights	'	'	'	'	'	'10 years	'	'
Gain from settlement of retention option	'	'	'	'	31,079,000	31,079,000	'	'
Fair value of BUPHENYL	'	'	'	'	'	20,400,000	'	'
Net payment received from Ucyclyd	'	'	'	'	10,962,000	10,962,000	'	'
Option to purchase rights to BUPHENYL and AMMONUL	'	'	'	'	283,000	283,000	'	'
Business combination acquisition related costs	'	'	'	'	'	'	'	$600,000

Schedule_of_Purchase_Price_All

Schedule of Purchase Price Allocation (Detail) (BUPHENYL, USD $)	31-May-13
In Thousands, unless otherwise specified
BUPHENYL	'
Business Acquisition [Line Items]	'
Inventories	$3,900
Intangible Asset - BUPHENYL Product rights	16,500
Purchase Price and Fair Values of Assets Acquired, Total	$20,400

Total_Gain_from_BUPHENYL_Acqui

Total Gain from BUPHENYL Acquisition (Detail) (USD $)	12 Months Ended	0 Months Ended
	Dec. 31, 2013	31-May-13
		BUPHENYL
Business Acquisition [Line Items]	'	'
Ucyclyd's retention option amount	'	$32,000,000
Amount due to Ucyclyd for BUPHENYL product rights	-19,000,000	-19,000,000
Amount due to Ucyclyd for inventory	-2,038,000	-2,038,000
Net payment received from Ucyclyd	10,962,000	10,962,000
Option to purchase rights to BUPHENYL and AMMONUL	-283,000	-283,000
Fair value of BUPHENYL	'	20,400,000
Gain from settlement of retention option	$31,079,000	$31,079,000

Consolidated_Pro_Forma_Informa

Consolidated Pro Forma Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Business Combinations [Abstract]	'	'
Net revenues	$52,900	$21,501
Net income (loss)	$24,266	($28,976)

Schedule_of_Investments_by_Con

Schedule of Investments by Contractual Maturity (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity for the Year, 2014	$28,075,000	'
Contractual Maturity for the Year, 2015	15,805,000	'
Contractual Maturity, Total Book Value	43,880,000	'
Unrealized Gain (Loss)	-55,000	'
Aggregate Fair Value	43,825,000	0
Certificates of deposit	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity for the Year, 2014	10,525,000	'
Contractual Maturity for the Year, 2015	2,845,000	'
Contractual Maturity, Total Book Value	13,370,000	'
Unrealized Gain (Loss)	-27,000	'
Aggregate Fair Value	13,343,000	'
Corporate notes	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity for the Year, 2014	6,047,000	'
Contractual Maturity for the Year, 2015	12,960,000	'
Contractual Maturity, Total Book Value	19,007,000	'
Unrealized Gain (Loss)	-24,000	'
Aggregate Fair Value	18,983,000	'
U.S. Government agency securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity for the Year, 2014	8,011,000	'
Contractual Maturity for the Year, 2015	'	'
Contractual Maturity, Total Book Value	8,011,000	'
Unrealized Gain (Loss)	-3,000	'
Aggregate Fair Value	8,008,000	'
Commercial paper	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Contractual Maturity for the Year, 2014	3,492,000	'
Contractual Maturity for the Year, 2015	'	'
Contractual Maturity, Total Book Value	3,492,000	'
Unrealized Gain (Loss)	-1,000	'
Aggregate Fair Value	$3,491,000	'

Investments_Additional_Informa

Investments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Investments Debt And Equity Securities [Abstract]	'	'
Aggregate fair value of investments	$43,825,000	$0
Other-than-temporary impairments	$0	'

Schedule_of_Unrealized_Losses_

Schedule of Unrealized Losses and Related Fair Value of Investments with Unrealized Losses (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'
Less Than 12 Months to Maturity, Aggregate Fair Value	$28,045
Less Than 12 Months to Maturity, Unrealized Losses	-30
12 Months or More to Maturity, Aggregate Fair Value	15,780
12 Months or More to Maturity, Unrealized Losses	-25
Aggregate Fair Value, Total	43,825
Unrealized Losses, Total	-55
Certificates of deposit	'
Schedule of Available-for-sale Securities [Line Items]	'
Less Than 12 Months to Maturity, Aggregate Fair Value	10,507
Less Than 12 Months to Maturity, Unrealized Losses	-18
12 Months or More to Maturity, Aggregate Fair Value	2,836
12 Months or More to Maturity, Unrealized Losses	-9
Aggregate Fair Value, Total	13,343
Unrealized Losses, Total	-27
Corporate notes	'
Schedule of Available-for-sale Securities [Line Items]	'
Less Than 12 Months to Maturity, Aggregate Fair Value	6,039
Less Than 12 Months to Maturity, Unrealized Losses	-8
12 Months or More to Maturity, Aggregate Fair Value	12,944
12 Months or More to Maturity, Unrealized Losses	-16
Aggregate Fair Value, Total	18,983
Unrealized Losses, Total	-24
U.S. Government agency securities	'
Schedule of Available-for-sale Securities [Line Items]	'
Less Than 12 Months to Maturity, Aggregate Fair Value	8,008
Less Than 12 Months to Maturity, Unrealized Losses	-3
12 Months or More to Maturity, Aggregate Fair Value	'
12 Months or More to Maturity, Unrealized Losses	'
Aggregate Fair Value, Total	8,008
Unrealized Losses, Total	-3
Commercial paper	'
Schedule of Available-for-sale Securities [Line Items]	'
Less Than 12 Months to Maturity, Aggregate Fair Value	3,491
Less Than 12 Months to Maturity, Unrealized Losses	-1
12 Months or More to Maturity, Aggregate Fair Value	'
12 Months or More to Maturity, Unrealized Losses	'
Aggregate Fair Value, Total	3,491
Unrealized Losses, Total	($1)

Hierarchy_for_Assets_and_Liabi

Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	$38,986,000	'
Fair value of available-for-sale securities	43,825,000	0
Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	480,000	'
Fair value of available-for-sale securities	13,343,000	'
Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	3,491,000	'
Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	18,983,000	'
U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	8,008,000	'
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	28,045,000	'
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	10,507,000	'
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	3,491,000	'
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	6,039,000	'
Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	8,008,000	'
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	15,780,000	'
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	2,836,000	'
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	12,944,000	'
Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	38,506,000	'
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 and cash equivalents	38,506,000	45,003,000
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Long-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Long-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Available-for-sale securities, Long-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Quoted Prices in Active Markets for Identical Items (Level 1) | Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	38,506,000	45,003,000
Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	480,000	'
Fair value of available-for-sale securities	43,825,000	'
Significant Other Observable Inputs (Level 2) | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	480,000	'
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	28,045,000	'
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	10,507,000	'
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	3,491,000	'
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	6,039,000	'
Significant Other Observable Inputs (Level 2) | Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	8,008,000	'
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	15,780,000	'
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	2,836,000	'
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	12,944,000	'
Significant Other Observable Inputs (Level 2) | Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	'	'
Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | Commercial paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Short-term | U.S. Government agency securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Long-term	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Long-term | Certificates of deposit	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Available-for-sale securities, Long-term | Corporate notes	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of available-for-sale securities	'	'
Significant Unobservable Inputs (Level 3) | Money market funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash and cash equivalents	'	'

Carrying_Value_and_Estimated_F

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

Components_of_Inventories_Deta

Components of Inventories (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw Materials	$697	'
Finished goods	2,816	'
Total	$3,513	'

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (BUPHENYL, USD $)	Dec. 31, 2013	31-May-13
BUPHENYL	'	'
Inventory [Line Items]	'	'
Remaining inventory at balance sheet date	'	$3,900,000
Acquisition of inventory	$400,000	'

Intangible_Asset_Additional_In

Intangible Asset - Additional Information (Detail) (USD $)	12 Months Ended	1 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2013	31-May-13
		BUPHENYL	BUPHENYL
Finite-Lived Intangible Assets [Line Items]	'	'	'
Intangible asset-BUPHENYL product rights	'	'	$16,500
Estimated useful life of intangible assets	'	'10 years	'
Amortization of intangible asset	$3,058	'	'

Schedule_of_Expected_Amortizat

Schedule of Expected Amortization Expense (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]	'
2014	$4,053
2015	3,294
2016	1,157
2017	1,048
2018	$1,012

Components_of_Property_and_Equ

Components of Property and Equipment (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$1,200	$363
Less: Accumulated depreciation	-264	-314
Total property and equipment, net	936	49
Computers and Software	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	563	95
Furniture and Fixtures	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	320	'
Office Equipment	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	53	21
Leasehold Improvements	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	'	247
Capital work in progress	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$264	'

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property Plant And Equipment [Abstract]	'	'	'
Depreciation expense	$200,000	$15,000	$100,000

Components_of_Accrued_Liabilit

Components of Accrued Liabilities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Payables And Accruals [Abstract]	'	'
Preclinical and clinical trial expenses	$246	$583
Payroll and related expenses	4,278	1,457
Gross to net sales accruals	5,235	'
Royalty payable	1,154	'
State taxes payable	326	'
Interest payable	61	93
Other	887	407
Accrued liabilities	$12,187	$2,540

Notes_Payable_Additional_Infor

Notes Payable - Additional Information (Detail) (USD $)	12 Months Ended	0 Months Ended	1 Months Ended	12 Months Ended			1 Months Ended		12 Months Ended
	Dec. 31, 2011	Jul. 31, 2012	Oct. 31, 2011	Dec. 31, 2012	31-May-11	Apr. 30, 2011	Oct. 31, 2011	Apr. 30, 2011	Dec. 31, 2011	Dec. 31, 2013
		April 2011 Convertible Notes Payable	April 2011 Convertible Notes Payable	April 2011 Convertible Notes Payable	April 2011 Convertible Notes Payable	April 2011 Convertible Notes Payable	April 2011 Call Option Liability	April 2011 Call Option Liability	April 2011 Call Option Liability	April 2011 Call Option Liability
Debt Instrument [Line Items]	'	'	'	'	'	'	'	'	'	'
Aggregate principal amount of notes issued	'	'	'	'	$8,285	$17,500,000	'	'	'	'
Aggregate principal amount that may be issued, maximum	'	'	'	35,000,000	'	'	'	'	'	'
Stated interest rate on notes	'	'	'	6.00%	'	'	'	'	'	'
Portion of principal amount outstanding for holders having early maturity date	'	'	'	66.00%	'	'	'	'	'	'
Minimum amount of proceeds from preferred stock	'	'	'	30,000,000	'	'	'	'	'	'
Principal and accrued interest converted upon closing of IPO	'	18,900,000	'	'	'	'	'	'	'	'
Number of shares issued upon conversion of notes	'	1,888,054	'	'	'	'	'	'	'	'
Carrying value and accrued interest	'	18,400,000	'	'	'	'	'	'	'	'
Aggregate principal amount in event that none of subsequent closing notes issued	'	'	'	'	'	'	'	'	'	7,500,000
Aggregate principal amount in event that all or portion of subsequent closing notes issued	'	'	'	'	'	'	'	'	'	10,500,000
Fair value of call option	'	'	'	'	'	'	'	900,000	'	'
Fair value of call option, Expected term	'	'	'	'	'	'	'	'7 months	'	'
Fair value of call option, Risk free interest rate	'	'	'	'	'	'	'	0.27%	'	'
Fair value of call option, Dividend yield	'	'	'	'	'	'	'	0.00%	'	'
Fair value of call option, Expected volatility	'	'	'	'	'	'	'	50.00%	'	'
Other Income (Expense)	'	'	'	'	'	'	'	'	300,000	'
Gain on extinguishment of debt	$1,143,000	'	$1,100,000	'	'	'	$600,000	'	'	'

Notes_Payable_Additional_Infor1

Notes Payable - Additional Information 1 (Detail) (USD $)

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

12 Months Ended

Jul. 31, 2012

Jul. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Feb. 29, 2012

Nov. 30, 2011

Oct. 31, 2011

Feb. 29, 2012

Oct. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Jul. 31, 2012

Dec. 31, 2012

31-May-11

Apr. 30, 2011

Dec. 31, 2011

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Call Option Liability

October 2011 Call Option Liability

October 2011 Call Option Liability

October 2011 Call Option Liability

April 2011 Convertible Notes Payable

April 2011 Convertible Notes Payable

April 2011 Convertible Notes Payable

April 2011 Convertible Notes Payable

April 2011 And October 2011 Notes Payable

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate principal amount of notes issued

'

'

'

'

$7,500,000

$3,551

$7,500,000

'

'

'

'

'

'

$8,285

$17,500,000

'

Aggregate principal amount that may be issued, maximum

'

'

15,000,000

'

'

'

'

'

'

'

'

'

35,000,000

'

'

'

Stated interest rate on notes

'

'

6.00%

'

'

'

'

'

'

'

'

'

6.00%

'

'

'

Portion of principal amount outstanding for holders having early maturity date

'

'

66.00%

'

'

'

'

'

'

'

'

'

66.00%

'

'

'

Minimum amount of proceeds from preferred stock

'

'

40,000,000

'

'

'

'

'

'

'

'

'

30,000,000

'

'

'

Principal and accrued interest converted upon closing of IPO

15,600,000

15,600,000

'

'

'

'

'

'

'

'

'

18,900,000

'

'

'

'

Number of shares issued upon conversion of notes

1,556,816

1,556,816

'

'

'

'

'

'

'

'

'

1,888,054

'

'

'

'

Carrying value and accrued interest

14,900,000

14,900,000

'

'

'

'

'

'

'

'

'

18,400,000

'

'

'

'

Aggregate principal amount in event that none of subsequent closing notes issued

'

'

'

'

'

'

'

'

'

'

7,500,000

'

'

'

'

'

Aggregate principal amount in event that all or portion of subsequent closing notes issued

'

'

'

'

'

'

'

'

'

'

7,500,000

'

'

'

'

'

Fair value of call option

'

'

'

'

'

'

'

'

800,000

700,000

'

'

'

'

'

'

Fair value of call option, Expected term

'

'

'

'

'

'

'

'

'8 months

'6 months

'

'

'

'

'

'

Fair value of call option, Risk free interest rate

'

'

'

'

'

'

'

'

0.12%

0.12%

'

'

'

'

'

'

Fair value of call option, Dividend yield

'

'

'

'

'

'

'

'

0.00%

0.00%

'

'

'

'

'

'

Fair value of call option, Expected volatility

'

'

'

'

'

'

'

'

50.00%

50.00%

'

'

'

'

'

'

Other Income (Expense)

'

'

'

'

'

'

'

700,000

'

100,000

'

'

'

'

'

'

Carrying value of notes

'

'

'

0

'

'

'

'

'

'

'

'

0

'

'

'

Amortization of debt discount

'

'

'

900,000

'

'

'

'

'

'

'

'

'

'

'

1,600,000

Beneficial conversion features

'

'

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

Notes_Payable_Additional_Infor2

Notes Payable - Additional Information 2 (Detail) (USD $)	12 Months Ended		1 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2013	Apr. 30, 2012	Sep. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
	April 2012 Notes Payable	April 2012 Notes Payable	September 2012 Notes Payable	September 2012 Notes Payable	September 2012 Notes Payable	April 2012 and September 2012 Notes Payable	April 2012 and September 2012 Notes Payable
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Aggregate principal amount of notes issued	'	$10,000,000	'	'	'	'	'
Stated interest rate on notes	8.88%	'	'	8.88%	'	'	'
Interest only payment period	'9 months	'	'	'9 months	'	'	'
Payment of loan principal and interest	'27 months	'	'	'27 months	'	'	'
Period for monthly financials and compliance certificate	'30 days	'	'	'	'	'	'
Period for annual audited financial report	'180 days	'	'	'	'	'	'
Number of warrants issued	'	75,974	'	'	8,408	'	'
Exercise price of warrants	'	4.08	'	'	5.05	'	'
Final payment due as a percentage of principal loan amount	6.50%	'	'	6.50%	'	'	'
Sale of equity securities or debt, minimum amount for term loan	30,000,000	'	'	'	'	'	'
Bank Term Loan	2,500,000	'	'	'	'	'	'
Additional borrowing	'	'	2,500,000	'	'	'	'
Percentage in addition to Treasury rate, term loan	'	'	'	8.50%	'	'	'
Amortization of debt discount	'	'	'	'	'	$500,000	$400,000

Future_Minimum_Payments_Under_

Future Minimum Payments Under April Twenty Twelve and September Twenty Twelve Notes (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
In Thousands, unless otherwise specified			April 2012 and September 2012 Notes Payable
Debt Instrument [Line Items]	'	'	'
2014	'	'	$6,152
2015	'	'	3,376
Total future minimum payments	'	'	9,528
Less: amount representing unamortized interest	'	'	-563
Less: amount representing debt discount	'	'	-692
Total minimum payments	'	'	8,273
Less: current portion	-5,652	-4,348	-5,652
Non-current portion	$2,621	$7,750	$2,621

Warrants_Additional_Informatio

Warrants - Additional Information (Detail) (USD $)

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

Sep. 30, 2012

Dec. 31, 2013

Dec. 31, 2013

Oct. 31, 2007

Apr. 30, 2008

Dec. 31, 2013

Apr. 30, 2011

Dec. 31, 2013

Jul. 31, 2012

31-May-11

Feb. 29, 2012

Oct. 31, 2011

Dec. 31, 2013

Jul. 31, 2012

Apr. 30, 2012

Dec. 31, 2013

September 2012 Common Stock Warrants

September 2012 Common Stock Warrants

October 2007 Common Stock Warrants

October 2007 Common Stock Warrants

April 2008 Common Stock Warrants

April 2008 Common Stock Warrants

April 2011 Common Stock Warrants Liability

April 2011 Common Stock Warrants Liability

April 2011 Common Stock Warrants Liability

April 2011 Common Stock Warrants Liability

October 2011 Preferred Stock Warrants

October 2011 Preferred Stock Warrants

October 2011 Preferred Stock Warrants

October 2011 Preferred Stock Warrants

April 2012 Common Stock Warrants

April 2012 Common Stock Warrants

Class of Warrant or Right [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of warrants issued

8,408

'

'

274

22

'

'

'

'

'

'

'

'

'

75,974

'

Exercise price of warrants

5.05

5.05

1,913.05

'

327.95

'

4.08

'

'

4.08

'

'

9.62

'

4.08

4.08

Expiration date of warrants

'

'September 2022

'October 2017

'

'

'December 31, 2012

'

'

'

'

'

'

'

'

'

'April 2022

Fair value of warrants

$75,000

'

'

'

$4,500

'

$1,100,000

'

'

'

$500,000

$400,000

'

'

$700,000

'

Fair value of warrants, Expected volatility

65.00%

'

'

'

71.00%

'

70.00%

'

'

'

70.00%

70.00%

'

'

70.00%

'

Fair value of warrants, Risk free interest rate

1.65%

'

'

'

2.84%

'

0.80%

'

'

'

0.20%

0.12%

'

'

1.98%

'

Fair value of warrants, Exercise price

'

'

'

'

$327.95

'

'

'

'

'

'

'

'

'

'

'

Fair value of warrants, Expected term

'10 years

'

'

'

'5 years

'

'2 years

'

'

'

'1 year

'1 year 6 months

'

'

'10 years

'

Percentage of principal amount to determine shares under warrants

'

'

'

'

'

'

'

30.00%

'

'

'

'

30.00%

'

'

'

Price used to determine shares under warrants

'

'

'

'

'

'

'

$9.62

'

'

'

'

$9.62

'

'

'

Shares issued for conversion of warrants upon closing of IPO

'

'

'

'

'

'

'

'

322,599

'

'

'

'

17,762

'

'

Warrants_Additional_Informatio1

Warrants - Additional Information 1 (Detail) (USD $)	1 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended	1 Months Ended			12 Months Ended
	Apr. 30, 2011	Dec. 31, 2012	Feb. 29, 2012	Oct. 31, 2011	Dec. 31, 2012	Feb. 29, 2012	Apr. 30, 2012	Sep. 30, 2012	Dec. 31, 2013	Jul. 31, 2012
	April 2011 Common Stock Warrants Liability	April 2011 Common Stock Warrants Liability	October 2011 Preferred Stock Warrants	October 2011 Preferred Stock Warrants	October 2011 Preferred Stock Warrants	Second closing - October 2011 preferred stock warrants	April 2012 Common Stock Warrants	September 2012 Common Stock Warrants	April 2011 common stock warrants and October 2011 preferred stock warrants	April 2011 common stock warrants and October 2011 preferred stock warrants
Class of Warrant or Right [Line Items]	'	'	'	'	'	'	'	'	'	'
Fair value of warrants, Expected term	'2 years	'	'1 year	'1 year 6 months	'	'1 year	'10 years	'10 years	'	'
Fair value of warrants, Expected volatility	70.00%	'	70.00%	70.00%	'	70.00%	70.00%	65.00%	'	'
Fair value of warrants, Risk free interest rate	0.80%	'	0.20%	0.12%	'	0.20%	1.98%	1.65%	'	'
Fair value of warrants	$1,100,000	'	$500,000	$400,000	'	$500,000	$700,000	$75,000	'	$3,900,000
Other income (expense), net	'	($1,500,000)	'	'	$700,000	'	'	'	($800,000)	'

Summary_of_Outstanding_Warrant

Summary of Outstanding Warrants and Corresponding Exercise Price (Detail)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2012
			October 2007 Common Stock Warrants	October 2007 Common Stock Warrants	April 2012 Common Stock Warrants	April 2012 Common Stock Warrants	April 2012 Common Stock Warrants	September 2012 Common Stock Warrants	September 2012 Common Stock Warrants	September 2012 Common Stock Warrants
Class of Warrant or Right [Line Items]	'	'	'	'	'	'	'	'	'	'
Number of Shares Outstanding	274	84,656	274	274	'	75,974	'	'	8,408	'
Per Share Exercise Price	'	'	1,913.05	'	4.08	'	4.08	5.05	'	5.05

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Oct. 14, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 12, 2013
	sqft				sqft
Commitments And Contingencies Disclosure [Abstract]	'	'	'	'	'
Leased space	20,116	'	'	'	352
Initial lease term	'	'6 years	'	'	'
Total base rent	$4.50	'	'	'	'
Lease commencement date	'	19-Nov-13	'	'	'
Total monthly base rent	'	0.1	'	'	'
Lease expiration date	'	'2016-12	'	'	'
Rent expense including maintenance fees	'	$0.40	$0.30	$0.40	'

Future_Minimum_Lease_Payments_

Future Minimum Lease Payments (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]	'
2014	$518
2015	797
2016	820
2017	821
2018	845
Thereafter	766
Total	$4,567

Preferred_Stock_Additional_Inf

Preferred Stock - Additional Information (Detail) (USD $)	0 Months Ended			1 Months Ended
In Millions, except Share data, unless otherwise specified	Jul. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2010	Dec. 31, 2009	Jun. 30, 2009	Jul. 31, 2012	Jul. 31, 2012
				Series C-2 Convertible Preferred Stock	Series C-2 Convertible Preferred Stock	Series C-2 Convertible Preferred Stock	Series C-2 Convertible Preferred Stock	Series C-1 Convertible Preferred Stock
Temporary Equity [Line Items]	'	'	'	'	'	'	'	'
Total value of preferred stock converted	$58.30	'	'	'	'	'	'	'
Issuance of common stock for converted preferred stock	'	'	'	'	'	'	4,663,039	1,912,598
Preferred stock, authorized	10,000,000	10,000,000	10,000,000	'	'	'	'	'
Preferred stock, par value	$0.00	$0.00	$0.00	'	'	'	'	'
Preferred stock, outstanding	'	'	'	'	'	'	'	'
Issuance of stock	5,000,000	'	'	'	'	2,331,116	'	'
Issuance of stock, per share	'	'	'	'	'	$9.62	'	'
Freestanding instrument liability	'	'	'	'	'	1.4	'	'
Fair value of preferred stock, Expected term	'	'	'	'3 months	'6 months	'1 year	'	'
Fair value of preferred stock, Risk free interest rate	'	'	'	0.16%	0.20%	0.56%	'	'
Fair value of preferred stock, Expected volatility	'	'	'	45.00%	45.00%	45.00%	'	'
Freestanding instrument liability fair value	'	'	'	0.4	0.7	'	'	'
Change in fair value recorded in other expense (income), net	'	'	'	$1.10	$0.60	'	'	'

Common_Stock_Additional_Inform

Common Stock - Additional Information (Detail) (USD $)

0 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

Jul. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Aug. 14, 2013

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2011

Jul. 31, 2012

Jun. 30, 2009

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Mar. 13, 2013

Vote

April 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

October 2011 Convertible Notes Payable

Series C-1 Convertible Preferred Stock

Series C-2 Convertible Preferred Stock

Series C-2 Convertible Preferred Stock

April 2011 Common Stock Warrants Liability

October 2011 Preferred Stock Warrants Liability

April 2011 common stock warrants and October 2011 preferred stock warrants

Initial Public Offering

Follow-on offering

Common Stock [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, shares issued

5,000,000

'

'

'

'

'

'

'

2,331,116

'

'

'

'

'

2,875,000

Offering price per share

$10

'

'

'

'

'

'

'

'

'

'

'

'

'

$20.75

Additional shares issued for over-allotment

750,000

'

'

'

'

'

'

'

'

'

'

'

'

'

431,250

Net proceeds from initial public offering

'

'

$53,475,000

'

'

'

'

'

'

'

'

'

'

$51,300,000

'

Underwriting discounts and commissions

'

4,116,000

4,025,000

'

'

'

'

'

'

'

'

'

'

4,025,000

4,116,000

Other offering expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

2,200,000

800,000

Total value of preferred stock converted

58,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Issuance of common stock for converted preferred stock

'

'

'

'

'

'

'

1,912,598

'

4,663,039

'

'

'

'

'

Principal and accrued interest converted upon closing of IPO

'

'

'

'

18,900,000

15,600,000

15,600,000

'

'

'

'

'

'

'

'

Number of shares issued upon conversion of notes

'

'

'

'

1,888,054

1,556,816

1,556,816

'

'

'

'

'

'

'

'

Carrying value and accrued interest

'

'

'

'

18,400,000

14,900,000

14,900,000

'

'

'

'

'

'

'

'

Shares issued for conversion of warrants upon closing of IPO

'

'

'

'

'

'

'

'

'

'

322,599

17,762

'

'

'

Fair value of warrants

'

'

'

'

'

'

'

'

'

'

'

'

3,900,000

'

'

Common stock, authorized

100,000,000

100,000,000

100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, par value

$0.00

$0.00

$0.00

'

'

'

'

'

'

'

'

'

'

'

'

Votes per common stock

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net proceeds from public offering

'

64,488,000

'

'

'

'

'

'

'

'

'

'

'

'

63,700,000

Aggregate offering price

'

'

'

150,000,000

'

'

'

'

'

'

'

'

'

'

'

Common stock shares sold by selling stockholders

'

'

'

8,727,000

'

'

'

'

'

'

'

'

'

'

'

Aggregate offering price under sales agreement

'

'

'

$50,000,000

'

'

'

'

'

'

'

'

'

'

'

Common_Stock_Reserved_for_Futu

Common Stock Reserved for Future Issuances (Detail)	Dec. 31, 2013
Common Stock [Line Items]	'
Common stock reserved for future issuance	3,385,663
Stock options | 2012 Plan	'
Common Stock [Line Items]	'
Common stock reserved for future issuance	576,760
Stock Option Exercises | 2006 and 2012 Plan	'
Common Stock [Line Items]	'
Common stock reserved for future issuance	2,790,629
Restricted Stock Awards Vesting | 2012 Plan	'
Common Stock [Line Items]	'
Common stock reserved for future issuance	18,000
Conversion of Common Stock Warrants	'
Common Stock [Line Items]	'
Common stock reserved for future issuance	274

Stock_Option_Plan_Additional_I

Stock Option Plan - Additional Information (Detail) (USD $)

0 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2006

Dec. 31, 2006

Dec. 31, 2006

Dec. 31, 2006

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Inventory

2006 Plan

2006 Plan

2006 Plan

2006 Plan

2006 Plan

2012 Plan

2012 Plan

2012 Plan

2012 Plan

2012 Plan

2012 Plan

Minimum

Persons Possessing 10% or More of Combined Voting Power

Persons Possessing 10% or More of Combined Voting Power

Restricted Stock

Restricted Stock

Restricted Stock

Minimum

Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares reserved for issuance

'

'

'

'

'

'

'

457

'

'

'

576,760

907,908

'

'

'

'

Minimum exercise price as a percentage of fair market value

'

'

'

'

'

'

'

'

100.00%

'

110.00%

'

'

'

'

'

'

Percentage of voting rights held by individual causing change in exercise price

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

Term of option

'

'

'

'

'

'

'

'10 years

'

'5 years

'

'

'

'

'

'

'

Minimum vesting percentage per year

'

'

'

'

'

'

'

'

20.00%

'

'

'

'

'

'

'

'

Vesting term

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

'

'

'

'

Aggregate intrinsic value of options exercised

'

'

'

'

'

'

$1,700,000

'

'

'

'

$200,000

'

'

'

'

'

Closing price of common stock

$20.22

$11.28

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of options vested and expected to vest

'

'

'

'

'

'

1,528,777

'

'

'

'

1,209,345

'

'

'

'

'

Options vested and expected to vest, intrinsic value

'

'

'

'

'

'

25,700,000

'

'

'

'

2,400,000

'

'

'

'

'

Options vested and expected to vest, weighted average exercise price

'

'

'

'

'

'

$3.63

'

'

'

'

$20.72

'

'

'

'

'

Options vested and expected to vest, weighted average remaining life

'

'

'

'

'

'

'6 years 9 months 18 days

'

'

'

'

'8 years 8 months 12 days

'

'

'

'

'

Stock options granted

'

'

'

'

'

'

'

'

'

'

'

1,067,315

720,580

407,946

'

'

'

Weighted-average grant date fair value of options granted

'

'

$22.90

$6.76

$2.37

'

'

'

'

'

'

'

'

'

'

'

'

Stock-based compensation

'

'

4,321,000

993,000

345,000

'

'

'

'

'

'

'

'

'

'

'

'

Unrecognized compensation cost

12,700,000

'

12,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Period of recognition for unrecognized compensation cost

'

'

'2 years 8 months 5 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted stock units, Granted

'

'

'

'

'

'

'

'

'

'

'

'

'

'

21,000

0

0

Stock-based compensation capitalized to inventory

'

'

'

'

'

$82,000

'

'

'

'

'

'

'

'

'

'

'

Schedule_of_Option_Activity_De

Schedule of Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
2006 Plan	'	'	'
Number of Shares Available for Grant	'	'	'
Beginning Balance	'	'	'
Options re-allocated	23,046	'	'
Options and awards cancelled	23,046	'	'
Ending Balance	'	'	'
Number of Shares Underlying Outstanding Options	'	'	'
Beginning Balance	1,661,522	'	'
Options exercised	-100,280	'	'
Options and awards cancelled	-23,046	'	'
Ending Balance	1,538,196	'	'
Weighted-Average Exercise Price Per Share	'	'	'
Beginning Balance	$3.73	'	'
Options exercised	$4.62	'	'
Options and awards cancelled	$5.68	'	'
Ending Balance	$3.64	'	'
2012 Plan	'	'	'
Number of Shares Available for Grant	'	'	'
Beginning Balance	907,908	'	'
Additional shares authorized	665,850	'	'
Options and awards granted	-1,088,315	'	'
Options re-allocated	23,046	'	'
Options and awards cancelled	68,271	'	'
Ending Balance	576,760	907,908	'
Number of Shares Underlying Outstanding Options	'	'	'
Beginning Balance	267,232	'	'
Options and awards granted	1,067,315	720,580	407,946
Options exercised	-16,843	'	'
Options and awards cancelled	-65,271	'	'
Ending Balance	1,252,433	267,232	'
Weighted-Average Exercise Price Per Share	'	'	'
Beginning Balance	$10.60	'	'
Options and awards granted	$22.90	'	'
Options exercised	$10.33	'	'
Options and awards cancelled	$17.01	'	'
Ending Balance	$20.75	$10.60	'
2012 Plan | Restricted Stock	'	'	'
Number of Shares Available for Grant	'	'	'
Beginning Balance	'	'	'
Options and awards granted	21,000	0	0
Options and awards cancelled	-3,000	'	'
Ending Balance	18,000	'	'
Options Vested and Exercisable	'	'	'
Options and awards granted	$19.39	'	'
Ending Balance	$19.39	'	'

Aggregate_Options_Outstanding_

Aggregate Options Outstanding and Vested and Exercisable by Exercise Price (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
2006 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Number Outstanding	1,538,196	1,661,522
Options Outstanding, Aggregate Intrinsic Value	$25,787,000	$12,840,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'6 years 9 months 18 days	'7 years 10 months 24 days
Options Vested and Exercisable, Options Number Outstanding	1,258,806	1,044,380
Options Vested and Exercisable, Aggregate Intrinsic Value	21,861,000	9,552,000
2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Number Outstanding	1,252,433	267,232
Options Outstanding, Aggregate Intrinsic Value	2,444,000	183,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'9 years 2 months 12 days	'9 years 9 months 18 days
Options Vested and Exercisable, Options Number Outstanding	86,531	2,291
Options Vested and Exercisable, Aggregate Intrinsic Value	837,000	2,200
Exercise Price 1 | 2006 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$1.28	$1.28
Options Outstanding, Number Outstanding	821,322	836,292
Options Outstanding, Aggregate Intrinsic Value	15,556,000	8,363,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'5 years 10 months 24 days	'6 years 10 months 24 days
Options Vested and Exercisable, Options Number Outstanding	820,056	814,675
Options Vested and Exercisable, Aggregate Intrinsic Value	15,532,000	8,147,000
Options Vested and Exercisable, Exercise Price	$1.28	$1.28
Exercise Price 1 | 2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	'	$10.32
Options Outstanding, Number Outstanding	225,768	20,000
Options Outstanding, Aggregate Intrinsic Value	2,183,000	19,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'8 years 9 months 18 days	'9 years 8 months 12 days
Options Vested and Exercisable, Options Number Outstanding	86,531	1,666
Options Vested and Exercisable, Aggregate Intrinsic Value	837,000	2,000
Options Vested and Exercisable, Exercise Price	'	$10.32
Exercise Price 1 | 2012 Plan | Minimum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$10.32	'
Options Vested and Exercisable, Exercise Price	$10.32	'
Exercise Price 1 | 2012 Plan | Maximum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$11.28	'
Options Vested and Exercisable, Exercise Price	$11.28	'
Exercise Price 2 | 2006 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$4.08	$4.08
Options Outstanding, Number Outstanding	305,873	373,037
Options Outstanding, Aggregate Intrinsic Value	4,937,000	2,686,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'7 years 3 months 18 days	'8 years 3 months 18 days
Options Vested and Exercisable, Options Number Outstanding	209,603	153,564
Options Vested and Exercisable, Aggregate Intrinsic Value	3,383,000	1,106,000
Options Vested and Exercisable, Exercise Price	$4.08	$4.08
Exercise Price 2 | 2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	'	$10.33
Options Outstanding, Number Outstanding	188,000	117,732
Options Outstanding, Aggregate Intrinsic Value	257,000	112,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'9 years 1 month 6 days	'9 years 7 months 6 days
Exercise Price 2 | 2012 Plan | Minimum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$18.24	'
Options Vested and Exercisable, Exercise Price	$18.24	'
Exercise Price 2 | 2012 Plan | Maximum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$19.39	'
Options Vested and Exercisable, Exercise Price	$19.39	'
Exercise Price 3 | 2006 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$7.31	$7.31
Options Outstanding, Number Outstanding	410,061	451,253
Options Outstanding, Aggregate Intrinsic Value	5,294,000	1,791,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'8 years 3 months 18 days	'9 years 3 months 18 days
Options Vested and Exercisable, Options Number Outstanding	228,207	75,201
Options Vested and Exercisable, Aggregate Intrinsic Value	2,946,000	299,000
Options Vested and Exercisable, Exercise Price	$7.31	$7.31
Exercise Price 3 | 2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	'	$10.61
Options Outstanding, Number Outstanding	121,625	69,500
Options Outstanding, Aggregate Intrinsic Value	4,000	47,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'9 years 6 months	'10 years
Exercise Price 3 | 2012 Plan | Minimum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$20.07	'
Options Vested and Exercisable, Exercise Price	$20.07	'
Exercise Price 3 | 2012 Plan | Maximum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$21.45	'
Options Vested and Exercisable, Exercise Price	$21.45	'
Exercise Price 4 | 2006 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$327.95	$327.95
Options Outstanding, Number Outstanding	940	940
Options Outstanding, Weighted Average Remaining Life (in Years)	'4 years	'5 years
Options Vested and Exercisable, Options Number Outstanding	940	940
Options Vested and Exercisable, Exercise Price	$327.95	$327.95
Exercise Price 4 | 2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	'	$10.95
Options Outstanding, Number Outstanding	86,200	15,000
Options Outstanding, Aggregate Intrinsic Value	'	5,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'9 years 6 months	'9 years 9 months 18 days
Options Vested and Exercisable, Options Number Outstanding	'	625
Options Vested and Exercisable, Aggregate Intrinsic Value	'	$200
Options Vested and Exercisable, Exercise Price	'	$10.95
Exercise Price 4 | 2012 Plan | Minimum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$22	'
Options Vested and Exercisable, Exercise Price	$22	'
Exercise Price 4 | 2012 Plan | Maximum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$22.06	'
Options Vested and Exercisable, Exercise Price	$22.06	'
Exercise Price 5 | 2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	'	$11.28
Options Outstanding, Number Outstanding	536,140	45,000
Options Outstanding, Weighted Average Remaining Life (in Years)	'9 years 3 months 18 days	'10 years
Exercise Price 5 | 2012 Plan | Minimum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$24.38	'
Options Vested and Exercisable, Exercise Price	$24.38	'
Exercise Price 5 | 2012 Plan | Maximum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$24.94	'
Options Vested and Exercisable, Exercise Price	$24.94	'
Exercise Price 6 | 2012 Plan	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Number Outstanding	94,700	'
Options Outstanding, Weighted Average Remaining Life (in Years)	'9 years 6 months	'
Exercise Price 6 | 2012 Plan | Minimum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$25.05	'
Options Vested and Exercisable, Exercise Price	$25.05	'
Exercise Price 6 | 2012 Plan | Maximum	'	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]	'	'
Options Outstanding, Exercise Price	$26.50	'
Options Vested and Exercisable, Exercise Price	$26.50	'

WeightedAverage_Assumptions_fo

Weighted-Average Assumptions for Fair Value of Stock Options (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'
Expected volatility	58.00%	65.00%	62.00%
Risk-free interest rate	1.14%	1.05%	2.48%
Dividend yield	0.00%	0.00%	0.00%
Expected term (in years)	'5 years 11 months 16 days	'6 years	'6 years 4 days

Allocation_of_StockBased_Compe

Allocation of Stock-Based Compensation Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expenses related to employees	$4,321	$993	$345
Cost of sales	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expenses related to employees	27	'	'
Research and development	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expenses related to employees	585	374	137
Selling general and administrative	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expenses related to employees	$3,709	$619	$208

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Tax Credit Carryforward [Line Items]	'	'	'
Income (loss) before income taxes	$16,676,000	($32,263,000)	($29,416,000)
Statutory federal income tax rate	35.00%	34.00%	34.00%
Increase (decrease) in deferred tax asset valuation allowance	-4,900,000	12,000,000	17,700,000
Deferred tax asset valuation allowance, excess tax deductions from stock-based compensation expense	1,133,000	178,000	'
Minimum percentage of stock for change of ownership	50.00%	'	'
Term of acquisition/sales for change of ownership	'3 years	'	'
Percentage of total equity value of acquiree or seller for change in ownership	5.00%	'	'
Prepaid expenses and other current assets	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Current deferred income tax asset	100,000	'	'
Other non-current assets	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Non-current deferred income tax asset	200,000	'	'
United States	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Net operating loss carryforwards	72,500,000	'	'
Operating loss expirations	'Begin to expire in 2026	'	'
United States | Research And Development Tax Credit Carryforward	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Tax credit carryforward	18,000,000	'	'
California	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Net operating loss carryforwards	112,500,000	'	'
Operating loss expirations	'Begin to expire in 2016	'	'
California | Research And Development Tax Credit Carryforward	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Tax credit carryforward	800,000	'	'
Minimum	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Statutory federal income tax rate	34.00%	'	'
Minimum | United States | Research And Development Tax Credit Carryforward	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Tax credit carryforward expiration	'2027	'	'
Maximum	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Statutory federal income tax rate	35.00%	'	'
Federal Orphan Drug Credit | United States | Research And Development Tax Credit Carryforward	'	'	'
Tax Credit Carryforward [Line Items]	'	'	'
Tax credit carryforward	$17,400,000	'	'

Components_of_Income_Tax_Expen

Components of Income Tax Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current income tax expense:	'	'	'
State	$326	'	'
Total current income tax expense	326	'	'
Deferred income tax benefit:	'	'	'
State	-277	'	'
Total deferred income tax benefit	-277	'	'
Total income tax expense	$49	'	'

Reconciliation_of_Income_Tax_E

Reconciliation of Income Tax Expense (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Statutory rate	35.00%	34.00%	34.00%
State tax	5.50%	5.40%	5.40%
Tax credits	-5.00%	0.70%	24.80%
Stock options	0.20%	-0.70%	-0.30%
Valuation allowance	-29.60%	-37.10%	-60.10%
Change in federal tax rate	-6.00%	'	'
Other	0.20%	-2.30%	-3.80%
Effective Income Tax Rate, Continuing Operations, Total	0.30%	0.00%	0.00%

Components_of_Deferred_Income_

Components of Deferred Income Tax Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred income tax assets	'	'
Fixed assets, capitalized intangibles and other assets	$5,294	$5,335
Net operating loss	31,842	39,616
Tax credits	18,480	16,907
Stock-based compensation expense	1,133	178
Other	1,527	869
Total	58,276	62,905
Valuation allowance	-58,000	-62,905
Net deferred income tax assets	$276	'

Reconciliation_of_Beginning_an

Reconciliation of Beginning and Ending Balances of Unrecognized Income Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Balance at the beginning of the year	$5,723	$5,357	$625
Changes based on prior period tax positions	'	-228	2,839
Changes based on current period tax positions	546	594	1,893
Balance at the end of the year	$6,269	$5,723	$5,357

Defined_Contribution_Plan_Addi

Defined Contribution Plan - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]	'
Amount of contribution to Plan	$0.20

Recovered_Sheet1

Net Income (Loss) Per Share of Common Stock (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income (loss) per share Numerator:	'	'	'	'	'	'	'	'	'	'	'
Net income (loss) attributable to common stockholders	$468	$112	$25,022	($8,975)	($8,285)	($4,930)	($7,162)	($11,886)	$16,627	($32,263)	($29,416)
Denominator:	'	'	'	'	'	'	'	'	'	'	'
Basic	'	'	'	'	'	'	'	'	19,415,822	7,256,537	469,319
Dilutive effect of stock-options and awards	'	'	'	'	'	'	'	'	1,315,091	'	'
Diluted	'	'	'	'	'	'	'	'	20,730,913	7,256,537	469,319
Net income (loss) per share:	'	'	'	'	'	'	'	'	'	'	'
Basic	$0.02	$0.01	$1.25	($0.52)	'	'	'	'	$0.86	($4.45)	($62.68)
Diluted	$0.02	$0.01	$1.17	($0.52)	'	'	'	'	$0.80	($4.45)	($62.68)

Antidilutive_Securities_Exclud

Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'
Potentially dilutive securities excluded from the computation of diluted net loss per share	1,027,879	2,013,410	8,186,653
Convertible preferred stock	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'
Potentially dilutive securities excluded from the computation of diluted net loss per share	'	'	6,575,637
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	1,027,605	1,928,754	1,279,240
Common and preferred 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	84,656	331,776

Related_Party_Transaction_Addi

Related Party Transaction - Additional Information (Detail) (Swedish Orphan Biovitrum AB, USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Swedish Orphan Biovitrum AB	'
Related Party Transaction [Line Items]	'
Sales recognized	$2.20
Accounts receivable from SOBI	$0.70

Selected_Unaudited_Quarterly_F

Selected Unaudited Quarterly Financial Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Product revenue, net	$18,627	$15,489	$7,305	$783	'	'	'	'	$42,204	'	'
Costs and expenses	17,747	15,037	12,986	9,851	7,795	4,758	4,755	11,225	55,621	28,533	26,159
Net income (loss) attributable to common stockholders	$468	$112	$25,022	($8,975)	($8,285)	($4,930)	($7,162)	($11,886)	$16,627	($32,263)	($29,416)
Net income (loss) per share attributable to common stockholders - basic	$0.02	$0.01	$1.25	($0.52)	'	'	'	'	$0.86	($4.45)	($62.68)
Net loss per share attributable to common stockholders - basic and diluted	'	'	'	'	($0.50)	($0.44)	($15.26)	($25.33)	'	'	'
Net income (loss) per share attributable to common stockholders - diluted	$0.02	$0.01	$1.17	($0.52)	'	'	'	'	$0.80	($4.45)	($62.68)