XenoPort (XNPT) Inactive 10-K27 Feb 152014 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2014	Feb. 13, 2015	Jun. 30, 2014
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	XNPT
Entity Registrant Name	XENOPORT INC
Entity Central Index Key	1130591
Current Fiscal Year End Date	-19
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		62,756,809
Entity Public Float			$250,400,000

BALANCE_SHEETS

BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$11,958	$20,584
Short-term investments	90,098	38,074
Accounts receivable	2,895	939
Inventories	1,458	1,262
Prepaids, restricted investments and other current assets	3,185	2,826
Total current assets	109,594	63,685
Property and equipment, net	2,422	2,552
Long-term inventories	9,098	10,185
Restricted investments and other assets	1,947	2,119
Total assets	123,061	78,541
Current liabilities:
Accounts payable	2,835	1,432
Accrued compensation	7,148	2,741
Accrued preclinical and clinical costs	1,554	824
Other accrued liabilities	5,117	3,938
Deferred revenue	1,134	1,134
Total current liabilities	17,788	10,069
Deferred revenue	10,864	11,997
Other noncurrent liability	3,269	2,782
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 100,000 shares authorized; 62,475 and 47,800 shares issued and outstanding, at December 31, 2014 and 2013, respectively	62	48
Additional paid-in capital	677,924	591,128
Accumulated other comprehensive loss	-30
Accumulated deficit	-586,816	-537,483
Total stockholders' equity	91,140	53,693
Total liabilities and stockholders' equity	$123,061	$78,541

BALANCE_SHEETS_Parenthetical

BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	62,475,000	47,800,000
Common stock, shares outstanding	62,474,892	47,800,366

STATEMENTS_OF_COMPREHENSIVE_IN

STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Product sales, net	$20,173	$6,414
Collaboration revenue	26,134	1,137	11,515
Royalty revenue	561	400	109
Net revenue from unconsolidated joint operating activities			10,000
Total revenues	46,868	7,951	21,624
Operating expenses:
Cost of product sales	2,094	1,170
Research and development	23,679	33,325	42,947
Selling, general and administrative	70,194	59,084	30,244
Gain on litigation settlement			-20,499
Total operating expenses	95,967	93,579	52,692
Income (loss) from operations	-49,099	-85,628	-31,068
Interest income	253	213	254
Interest expense	-487	-468
Net income (loss)	-49,333	-85,883	-30,814
Other comprehensive loss:
Unrealized gains (losses) on available-for-sale securities	-30	-22	38
Comprehensive income (loss)	($49,363)	($85,905)	($30,776)
Basic and diluted net income (loss) per share	($0.81)	($1.81)	($0.78)
Shares used to compute basic and diluted net loss per share	60,856	47,545	39,434

STATEMENTS_OF_STOCKHOLDERS_EQU

STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)	Total	Glaxo Group Limited	Common Stock	Common Stock	Additional Paid-In Capital	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
In Thousands, except Share data	Total	Glaxo Group Limited	Common Stock	Glaxo Group Limited	Additional Paid-In Capital	Glaxo Group Limited	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2011	$75,135		$35		$495,902		($16)	($420,786)
Beginning Balance (in shares) at Dec. 31, 2011			35,514,636
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)			259,650
Issuance of common stock upon exercise of options and vesting of restricted stock units	-480		1		-481
Issuance of common stock in connection with Employee Stock Purchase Plan (in shares)	185,249		185,249
Issuance of common stock in connection with Employee Stock Purchase Plan	763				763
Employee stock-based compensation expense	12,281				12,281
Issuance of common stock (in shares)			7,076,922	4,031,212
Issuance of common stock	43,019	30,268	7	4	43,012	30,264
Change in unrealized gains (losses) on investments	38						38
Net loss	-30,814							-30,814
Ending Balance at Dec. 31, 2012	130,210		47		581,741		22	-451,600
Ending Balance (in shares) at Dec. 31, 2012			47,067,669
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)			590,242
Issuance of common stock upon exercise of options and vesting of restricted stock units	-1,875		1		-1,876
Issuance of common stock in connection with Employee Stock Purchase Plan (in shares)	142,455		142,455
Issuance of common stock in connection with Employee Stock Purchase Plan	719				719
Employee stock-based compensation expense	10,544				10,544
Change in unrealized gains (losses) on investments	-22						-22
Net loss	-85,883							-85,883
Ending Balance at Dec. 31, 2013	53,693		48		591,128			-537,483
Ending Balance (in shares) at Dec. 31, 2013	47,800,366		47,800,366
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)			646,806
Issuance of common stock upon exercise of options and vesting of restricted stock units	-395				-395
Issuance of common stock in connection with Employee Stock Purchase Plan (in shares)	227,720		227,720
Issuance of common stock in connection with Employee Stock Purchase Plan	714				714
Employee stock-based compensation expense	9,041				9,041
Issuance of common stock (in shares)			13,800,000
Issuance of common stock	77,450		14		77,436
Change in unrealized gains (losses) on investments	-30						-30
Net loss	-49,333							-49,333
Ending Balance at Dec. 31, 2014	$91,140		$62		$677,924		($30)	($586,816)
Ending Balance (in shares) at Dec. 31, 2014	62,474,892		62,474,892

STATEMENTS_OF_CASH_FLOWS

STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	($49,333)	($85,883)	($30,814)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	623	1,199	2,516
Accretion of investment discounts and amortization of investment premiums, net	1,151	1,007	1,295
Stock-based compensation expense	9,041	10,544	12,281
Gain on litigation settlement, net of stock premium in connection with the stock purchase agreement with GSK			-11,243
Changes in assets and liabilities:
Accounts receivable	-1,956	-939
Prepaids and other current and noncurrent assets	-186	16	712
Inventories	891	286
Accounts payable	1,403	865	-465
Accrued compensation	4,407	-2,134	699
Accrued restructuring charges		-993	-1,737
Accrued preclinical and clinical costs	730	-3,573	-36
Other accrued liabilities, current and noncurrent	1,666	2,839	677
Deferred revenue, current and noncurrent	-1,133	-1,137	-1,515
Net cash used in operating activities	-32,696	-77,903	-27,630
Investing activities
Purchases of investments	-155,885	-91,000	-147,645
Proceeds from maturities of investments	102,679	154,765	112,576
Purchases of property and equipment	-493	-256	-123
Net cash provided by (used in) investing activities	-53,699	63,509	-35,192
Financing activities
Net cash proceeds provided by (used in) issuance of common stock and exercise of stock options	77,769	-1,156	43,302
Proceeds from issuance of common stock to GSK in connection with the stock purchase agreement			30,268
Net cash provided by (used in) financing activities	77,769	-1,156	73,570
Net increase (decrease) in cash and cash equivalents	-8,626	-15,550	10,748
Cash and cash equivalents at beginning of period	20,584	36,134	25,386
Cash and cash equivalents at end of period	11,958	20,584	36,134
Non-cash investing activity
Right to the HORIZANT business			13,557
Inventories		11,733
Manufacturing property and equipment		$1,967

Organization_and_Summary_of_Si

Organization and Summary of Significant Accounting Policies	12 Months Ended
Organization and Summary of Significant Accounting Policies	Dec. 31, 2014
Organization and Summary of Significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies
	Nature of Operations
	XenoPort, Inc., or the Company, was incorporated in the state of Delaware on May 19, 1999. The Company is a biopharmaceutical company focused on developing and commercializing a portfolio of internally discovered product candidates for the potential treatment of neurological and other disorders. The Company is currently commercializing HORIZANT^® (gabapentin enacarbil) Extended-Release Tablets in the United States and developing its novel fumaric acid ester product candidate, XP23829, as a potential treatment for psoriasis and potentially for relapsing forms of multiple sclerosis, or MS. The Company’s other product candidates are: XP21279 and arbaclofen placarbil, or AP, which is licensed to Indivior PLC (formerly Reckitt Benckiser Pharmaceuticals, Inc.) Effective June 2014, the Company granted to Indivior exclusive, world-wide rights to develop and commercialize pharmaceutical products containing AP and other prodrugs of baclofen or R-baclofen, or collectively, the AP Products, for all indications, subject to the Company’s right of first negotiation with Indivior to collaborate to develop and commercialize AP Products for non-addiction indications (See Note 2 for more information). XP21279 is a potential treatment for patients with advanced idiopathic Parkinson’s disease. The Company may develop it further, to the extent that its resources permit, or it may enter into collaboration, partnership, licensing and other similar forms of revenue-generating transactions with third-party business partners for such development. HORIZANT and the Company’s product candidates are prodrugs that are typically created by modifying the chemical structure of currently marketed drugs, referred to as parent drugs, and are designed to correct limitations in the oral absorption, distribution and/or metabolism of the parent drug. HORIZANT and each of the Company’s product candidates are orally-available, patented molecules that address potential markets with clear unmet medical needs. The Company’s facilities are located in Santa Clara, California.
	On November 8, 2012, the Company reached an agreement with Glaxo Group Limited, or GSK, to terminate the Amended and Restated Development and Commercialization Agreement dated November 7, 2010, between the Company and GSK regarding HORIZANT and resolved all ongoing litigation between the parties. Under the terms of the November 2012 termination and transition agreement, during a transition period that ended on April 30, 2013, GSK continued to exclusively commercialize, promote, manufacture and distribute HORIZANT in the United States. The Company was not eligible to receive any milestone payments from GSK and did not receive any revenue or incur any losses from GSK’s sales of HORIZANT during the transition period. GSK continued to fully fund the costs associated with the management and conduct of required post-marketing clinical studies initiated by GSK prior to the date of the termination and transition agreement. In addition, GSK provided to the Company inventory of gabapentin enacarbil in GSK’s possession that was not required for use by GSK in the manufacture of HORIZANT and related manufacturing property and equipment. In exchange for such inventory, the Company will make annual payments to GSK of $1,000,000 for six years beginning in 2016, which was recorded at its present value as “Other noncurrent liability” on the Company’s balance sheet for the periods ended December 31, 2014 and 2013 and is being accreted at an effective interest rate of 17.5% to its contractual value over the payment period. On May 1, 2013, the Company completed the acquisition of the HORIZANT business in accordance with the termination and transition agreement and assumed all responsibilities and associated rights for the further development, manufacturing and commercialization of HORIZANT in the United States on that date. GSK was responsible for the commercial manufacture and supply of HORIZANT during the transition period. The Company did not assume any liabilities of GSK’s HORIZANT business as of the acquisition date.
	Basis of Preparation
	The Company’s financial statements are prepared in accordance with the Financial Accounting Standards Board, or FASB, Accounting Standards Codification, or the Codification, which is the single source of authoritative U.S. generally accepted accounting principles, or GAAP.

	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from these estimates.
	Fair Value of Financial Instruments
	The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents and short-term investments, restricted investments, accounts receivables and accounts payables, approximate their fair value due to their short-term maturities. The Company accounts for the fair value of its financial instruments in accordance with the provisions of the Fair Value Measurement topic of the Codification.
	Fair value is the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The Company applies the market approach valuation technique for fair value measurements on a recurring basis and attempts to maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. All of the Company’s cash equivalents and short-term investments are measured using inputs classified at Level 1 or Level 2 within the fair value hierarchy. Level 1 inputs are quoted prices in active markets for identical assets. Level 2 inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Level 3 inputs are unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes and market reference data.
	Cash Equivalents and Short-Term Investments
	The Company considers all highly liquid investments with original maturities of 90 days or less at the time of purchase to be cash equivalents, which primarily consist of money market funds, U.S. government-sponsored agencies and corporate debt securities.
	Management determines the appropriate classification of securities at the time of purchase. All investments have been designated as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company has classified all investments as short-term, even though the stated maturity may be one year or more beyond the current balance sheet date. Available-for-sale securities are carried at estimated fair value with unrealized gains and losses reported as a component of other comprehensive loss in the statements of comprehensive loss.
	The cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities, if any, are recorded in interest income and expense. The cost of securities sold is based on the specific-identification method. Interest and dividends are included in interest income.
	Restricted Investments
	Under a facilities operating lease agreement, the Company is required to secure a letter of credit with cash or securities. At December 31, 2014 and 2013, the Company recorded $1,500,000 of restricted investments related to the letter of credit (see Note 7 for more information). The $1,500,000 was classified as restricted investments in the accompanying balance sheets at both December 31, 2014 and 2013.

	In connection with the Company’s license to use radioactive materials in its research facilities, it must maintain a $225,000 letter of credit with the Radiological Health Branch of the State of California. This requirement has been fulfilled through certificates of deposit with a financial institution. The fair value of the secured amount of $225,000 was classified as restricted investments in the accompanying balance sheets at both December 31, 2014 and 2013.
	Segment Information
	The Company operates in one operating segment, which is the development and commercialization of product candidates for the potential treatment of neurological and other disorders, and has operations solely in the United States. To date, all of the Company’s revenues from product sales are related to sales of HORIZANT in the United States. The Company also has recognized upfront and milestone payments and royalty revenue from its partnership with Astellas Pharma Inc. and recognized upfront and additional payments from its partnership with Indivior (see Note 2 for more information on these arrangements).
	Concentrations of Risk
	The Company invests cash that is not being used for operational purposes. This exposes the Company to credit risk in the event of default by the institutions holding the cash and cash equivalents and available-for-sale securities to the extent of the amounts on its balance sheets. The credit risk is mitigated by the Company’s investment policy, which allows for the purchase of low risk debt securities issued by the U.S. government, U.S. government-sponsored agencies and highly rated banks and corporations, subject to certain concentration limits. The maturities of these securities are maintained at no longer than 16 months. The Company believes its established guidelines for investment of its excess cash enhances safety and liquidity through its policies on diversification and investment maturity.
	Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and available-for-sale investment securities in high-credit quality debt securities issued by the U.S. government, U.S. government-sponsored enterprises and highly rated banks and corporations. The carrying amounts of cash equivalents and available-for-sale investment securities are stated at fair value.
	The Company is subject to credit risk from its accounts receivable related to product sales. The Company’s trade accounts receivable arises from product sales in the United States. Three wholesale distributors represented 41%, 28% and 26%, respectively, of product sales for the year ended December 31, 2014. These three customers individually comprised 48%, 26% and 22%, respectively, of accounts receivable as of December 31, 2014. Three wholesale distributors represented 47%, 33% and 16%, respectively, of product sales for the year ended December 31, 2013. These three customers individually comprised 45%, 29% and 22%, respectively, of product sales related to accounts receivable as of December 31, 2013. To date, the Company has not experienced any losses with respect to the collection of its accounts receivable and believes that its accounts receivable are collectible.
	The Company relies on a single third-party contract manufacturer organization to manufacture HORIZANT.
	Property and Equipment
	Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the respective assets, which is generally five to ten years for the Company’s laboratory equipment, furniture and fixtures and manufacturing property and equipment and generally three years for the Company’s computer equipment and software. Leasehold improvements are amortized over their estimated useful lives or the remaining lease term, whichever is shorter.

	Revenue Recognition
	Product Sales
	The Company began selling HORIZANT to wholesalers in May 2013 following the return of the Company’s commercial rights from GSK. The Company recognizes revenue from HORIZANT product sales when there is persuasive evidence that an arrangement exists, delivery to the customer has occurred, the price is fixed or determinable and collectability is reasonably assured. Revenue from product sales is recorded net of estimated allowances for customer incentives such as cash discounts for prompt payment, distributor fees, expected returns, as appropriate (which are based on an analysis of historical return rates and deductions of HORIZANT, since its commercial launch by GSK in the second quarter of 2011), government rebates such as Medicaid reimbursements and patient assistance programs. Calculating certain of these items involves estimates and judgments based on contractual terms, historical utilization rates data for HORIZANT and new information regarding changes in these programs’ regulations and guidelines that would impact the amount of the actual rebates, the Company’s expectations regarding future utilization rates for these programs and channel inventory data. If future actual results vary from the Company’s estimates, the Company may need to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustment.
	Items Deducted from Gross Product Sales
	Prompt Pay Discount
	The Company offers cash discounts to its customers, generally 2% of the sales price, as an incentive for prompt payment. Based on the Company’s and GSK’s commercialization experience, the Company expects customers to continue to comply with the prompt payment terms to earn the cash discount as the Company is selling HORIZANT to the same customers under similar prompt payment terms and conditions. The Company estimates cash discounts for prompt payment based on contractual terms, GSK’s historical customer utilization rates and the Company’s historical customer utilization rates. The Company accounts for cash discounts by reducing accounts receivable by the full amount and recognizing the discount as a reduction of revenue in the same period the related revenue is recognized.
	Distributor Fees
	Under the Company’s inventory management agreements with significant wholesalers, the Company pays the wholesalers a fee primarily for distribution services as well as the maintenance of inventory levels. These distributor fees are based on a contractually determined fixed percentage of sales. The Company accrues the contractual amount and recognizes the discount as a reduction of revenue in the same period the related revenue is recognized.
	Product Returns
	The Company does not provide its customers with a general right of product return, but permits returns if the product is damaged or defective when received by the customer, or if the product has or is nearly expired. HORIZANT tablets currently have a shelf-life of 36 months from the date of manufacture. The Company will accept returns for products that will expire within six months or that have expired up to one year after their expiration dates. The Company obtained actual return history classified by the reasons for returns from GSK since GSK’s product launch in 2011, which provides a basis to reasonably estimate the Company’s future product returns. The Company estimates returns taking into consideration Company-specific adjustments to GSK’s returns history, the Company’s returns history, the shelf life of product, shipment and prescription trends and estimated distribution channel inventory levels.
	Government Rebates and Chargebacks
	The Company participates in a number of government rebate programs, such as the Medicaid Drug Rebate Program that provides assistance to eligible low-income patients based on each individual state’s guidelines regarding eligibility and services, Public Health Services or 340b programs, and the Medicare Part D Coverage Gap Discount Program, which provides rebates on prescriptions that fall within the “donut hole” coverage gap; and the Department of Veterans Affairs that offers discounts to authorized users of HORIZANT. HORIZANT is also listed on the Federal Supply Schedule, or FSS, of the General Services Administration which provides a discount to the Department of Defense, Department of Veterans Affairs, and TriCare. The Company estimates reductions to the Company’s revenues for government rebate programs based on product pricing, current rebates, GSK’s historical utilization rates, the Company’s actual utilization rates, new information regarding changes in these programs’ regulations and guidelines that would impact the amount of the actual rebates, the Company’s expectations regarding future rebates for these programs and estimated levels of inventory in the distribution channel.
	Patient Assistance
	The Company offers a co-pay card program to assist commercially insured patients with the cost of their HORIZANT related co-payments. Participating retail pharmacies get reimbursed by the Company for the amount of the co-pay assistance provided to eligible patients. The Company estimates and accrues the cost of the co-pay program based on historical redemption activity for this program. The Company reimburses the participating pharmacies approximately one month after the prescriptions subject to co-pay assistance are filled.
	Multiple-Element Arrangements
	Revenue arrangements are accounted for in accordance with the provisions of the Revenue Recognition-Multiple-Element Arrangements topic of the Codification.
	In evaluating arrangements with multiple elements, the Company considers whether components of the arrangement represent separate units of accounting based upon whether certain criteria are met, including whether the delivered element has stand-alone value to the customer and whether there is objective and reliable evidence of the fair value of the undelivered items. This evaluation requires subjective determinations and requires management to make judgments about the fair value of individual elements and whether such elements are separable from other aspects of the contractual relationship. The consideration received in such arrangements is allocated among the separate units of accounting based on the relative selling price method under which the selling price for each deliverable is determined using vendor-specific objective evidence of selling price, if it exists; otherwise, third-party evidence of selling price. If vendor-specific objective evidence and third-party evidence of selling price are not available for a deliverable, the Company will use its best estimate of the selling price for that deliverable when applying the relative selling price method. The applicable revenue recognition criteria are applied to each of the separate units.
	Revenues from multiple deliverables combined as a single unit of accounting are deferred and recognized over the period during which the Company remains obligated to perform services. The specific methodology for the recognition of the revenue (e.g., straight-line or according to specific performance criteria) is determined on a case-by-case basis according to the facts and circumstances applicable to a given agreement.
	Payments received in excess of revenues recognized are recorded as deferred revenue until such time as the revenue recognition criteria have been met.
	Collaboration revenue consisted of the recognition of revenues from upfront and milestone payments from the Company’s partnership with Astellas Pharma Inc. and from upfront and additional payments from its license agreement with Indivior. Net revenue from unconsolidated joint operating activities included all revenue that resulted solely from the Company’s terminated collaboration agreement with GSK. The Company accounts for the revenue-related activities of these collaboration agreements as follows:

		•		Up-front, licensing-type payments. Up-front, licensing-type payments are assessed to determine whether or not the licensee is able to obtain any stand-alone value from the license. Where this is not the case, the Company does not consider the license deliverable to be a separate unit of accounting, and the revenue is deferred with revenue recognition for the license fee being assessed in conjunction with the other deliverables that constitute the combined unit of accounting.

		•		Milestones. Revenue recognition will occur only if the consideration earned from the achievement of a milestone meets all the criteria for the milestone to be considered substantive at the inception of the arrangement, such that it: (i) is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the item delivered as a result of a specific outcome resulting from the Company’s performance to achieve the milestone; (ii) relates solely to past performance; and (iii) is reasonably relative to all deliverables and payment terms in the arrangement.
	The Company will assess the nature of contingent payments, and appropriate accounting for, these payments on a case-by-case basis in accordance with the provisions of the Revenue Recognition topic of the Codification.

		•		Profit and loss sharing. This represented the Company’s share of the profits and losses from the co-promotion of HORIZANT with GSK under the terminated collaboration with GSK. Amounts were recognized in the period in which the related activities occurred, and their financial statement classification was based on the Company’s assessment that these activities constituted part of the Company’s ongoing central operations.

		•		Product royalties. The Company is entitled to receive royalties on net sales of gabapentin enacarbil (known as REGNITE) in Japan. Astellas initiated sales of REGNITE in Japan in July 2012, and the Company recognizes the associated product royalties when they can be reliably measured and collectability is reasonably assured (generally upon receipt of the royalty payment).
	Cost of Product Sales
	Cost of product sales includes direct and indirect costs to manufacture product sold, including tableting, packaging, storage, shipping and handling costs and inventory write-downs, if any.
	Accounts Receivable
	Trade accounts receivable are recorded net of allowances for cash discounts for prompt payment, wholesaler discounts and chargebacks. The need for bad debt allowance is evaluated each reporting period based on the Company’s assessment of the credit worthiness of its customers.
	Inventories
Inventories are stated at the lower of cost or market. Cost is determined on a first-in, first-out, or FIFO, basis. Inventories include active pharmaceutical ingredient, or API, and contract manufacturing costs. The Company regularly evaluates the Company’s inventories for excess quantities and obsolescence (expiration), taking into account such factors as historical and anticipated future sales compared to quantities on hand and the remaining shelf life of HORIZANT. Write-downs of inventories are considered to be permanent reductions in the cost basis of inventories.
Inventories that are not expected to be consumed within 12 months following the balance sheet date are classified as long-term inventories.
Inventories as of December 31, 2014 and 2013 were summarized as follows (in thousands):


		Year Ended December 31,
		2014			2013
Raw materials		$	9,273		$	10,258
Work in progress			517			76
Finished goods			766			1,113

Total inventory			10,556			11,447
Less: Long-term inventories			9,098			10,185

Total inventory classified as current		$	1,458		$	1,262


Long-term inventories consisted of gabapentin enacarbil API used for production of HORIZANT. The Company evaluates demand for HORIZANT and expected consumption of the API based on long-term projected sales of HORIZANT.
Research and Development
All research and development costs, including those funded by third parties, are expensed as incurred. Research and development costs consisted of salaries, employee benefits, laboratory supplies, costs associated with clinical trials, including amounts paid to clinical research organizations, other professional services and facility costs.
Clinical Trials
The Company accrues and expenses the costs for clinical trial activities performed by third parties based upon estimates of the percentage of work completed over the life of the individual study in accordance with agreements established with contract research organizations and clinical trial sites. The Company determines the estimates through discussions with internal clinical personnel and external service providers as to progress or stage of completion of trials or services and the agreed upon fee to be paid for such services. Costs of setting up clinical trial sites for participation in the trials are expensed immediately as research and development expenses. Clinical trial site costs related to patient visits are accrued as patients’ progress through the trial and are reduced by any payments made to the clinical trial site. Non-refundable advance payments for research and development goods or services are recognized as expense as the related goods are delivered or the related services are provided in accordance with the provisions of the Research and Development Arrangements topic of the Codification.
Nonretirement Postemployment Benefits
On May 31, 2012, the Company adopted the XenoPort Amended and Restated 2012 Severance Plan, or the 2012 Severance Plan, for the benefit of the Company’s non-executive employees. Under the terms of the 2012 Severance Plan, a non-executive employee terminated by the Company because of elimination of his or her position is eligible to receive continuation of medical insurance under COBRA and specified severance payments based on the employee’s level and years of service with the Company. The Company accounts for employee termination benefits in accordance with the provisions of the Compensation-Nonretirement Postemployment Benefits topic of the Codification and records employee termination liabilities once they are both probable and estimable for severance provided under the Company’s existing severance program.
On June 14, 2013, the Company implemented a reduction in force that included the elimination of certain non-executive positions as the Company completed certain work projects on its AP development program. As a result, the Company recorded severance benefits charges of $703,000 in 2013, which were included in the “Research and development” line of the “Operating expenses” section of the Company’s statements of comprehensive loss. As of December 31, 2014 and 2013, there were no associated liability balances.
Stock-Based Compensation
The Compensation — Stock Compensation topic of the Codification establishes accounting for stock-based awards exchanged for employee services. In accordance with this topic, for stock options, awards and stock purchase rights under the Company’s employee stock purchase plan, or ESPP, stock-based compensation cost is measured at grant date, based on the fair value of the award, and is recognized as expense over the requisite employee service period.

The effect of recording stock-based compensation under the Compensation — Stock Compensation topic was as follows:


		Year Ended December 31,
		2014			2013			2012
		(In thousands, except
		per share amounts)
Stock-based compensation by type of award:
Employee stock options and awards		$	8,531		$	10,083		$	11,956
ESPP			510			461			325

Total stock-based compensation		$	9,041		$	10,544		$	12,281

Effect on basic and diluted net loss per share		$	(0.15	)	$	(0.22	)	$	(0.31	)

The Company’s employee non-cash stock-based compensation was reported as follows:


		Year Ended December 31,
		2014			2013			2012
		(In thousands)
Research and development		$	2,062		$	3,059		$	4,364
Selling, general and administrative			6,979			7,485			7,917

		$	9,041		$	10,544		$	12,281

Valuation Assumptions
The Company estimates the fair value of all of its stock options and stock purchase rights on the date of grant using a Black-Scholes valuation model that requires the input of highly subjective assumptions, including the option’s expected life and the price volatility of the underlying stock. The Company derived the expected life assumptions using data obtained from similar entities, taking into consideration factors such as industry, stage of life cycle, size and financial leverage. The Company has determined that its historical volatility can be used to derive the expected stock price volatility assumption. The Company expenses the resulting charge using the straight-line attribution method over the vesting period. Restricted stock units are measured at the fair value of the Company’s common stock on the date of grant and expensed over the period of vesting using the straight-line attribution approach. The calculation of the Black-Scholes valuations used the following weighted-average assumptions:


		Year Ended December 31,
		2014			2013			2012
Dividend yield			0	%		0	%		0	%
Volatility for options			0.81			0.82			0.81
Volatility for ESPP			0.55			0.59			0.65
Weighted-average expected life of options (years)			5.25			5.25			5.09
Weighted-average expected life of ESPP rights (years)			0.75			0.75			0.75
Risk-free interest rate for options			1.52-1.77	%		0.70-1.60	%		0.62-1.02	%
Risk-free interest rate for ESPP rights			0.05-0.17	%		0.07-0.17	%		0.07-0.27	%
Income Taxes
Income taxes are accounted for in accordance with the Income Taxes topic of the Codification using the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities as measured by the enacted tax rates that will be in effect when these differences reverse. The Company provides a valuation allowance against net deferred tax assets if, based upon the available evidence, it is more-likely-than-not that the deferred tax assets will not be realized.

The recognition, derecognition and measurement of a tax position is based on management’s best judgment given the facts, circumstances and information available at the reporting date.
As of December 31, 2014, the Company had unrecognized tax benefits and expects no significant changes in unrecognized tax benefits in the next 12 months (see Note 10 for more information).
The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense. To date, there have been no interest or penalties charged to the Company in relation to the underpayment of income taxes.
Comprehensive Loss
The Company presents all non-owner changes in stockholders’ equity in a single continuous statement of comprehensive loss and shows: (i) each component of net loss along with total net loss; (ii) each component of other comprehensive loss along with a total for other comprehensive loss; and (iii) a total amount for comprehensive loss. The Company’s other comprehensive loss is comprised of unrealized gains (losses) on available-for-sale securities.
Advertising Costs
Advertising costs, included in selling, general and administrative expenses, are charged to expense as incurred. Advertising expenses for the year ended December 31, 2014 and 2013, was $9,568,000 and $8,244,000, respectively. The Company did not have advertising costs for the year ended December 31, 2012.
Net Loss Per Share
Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period without consideration for potential common shares. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period plus any dilutive potential common shares for the period determined using the treasury-stock method. For purposes of this calculation, restricted stock units, options to purchase stock and warrants are considered to be potential common shares and are only included in the calculation of diluted net loss per share when their effect is dilutive.


		Year Ended December 31,
		2014			2013			2012
		(In thousands, except
		per share amounts)
Numerator:
Net loss		$	(49,333	)	$	(85,883	)	$	(30,814	)

Denominator:
Weighted-average common shares outstanding			60,856			47,545			39,434

Basic and diluted net loss per share		$	(0.81	)	$	(1.81	)	$	(0.78	)

Outstanding securities at period end not included in the computation of diluted net loss per share as they had an anti-dilutive effect:
Restricted stock units and options to purchase common stock			7,650			6,824			6,339
Warrants outstanding			—			283			283

			7,650			7,107			6,622

On January 29, 2014, the Company completed an underwritten public offering of 12,000,000 shares of its common stock at a price to the public of $6.00 per share. On February 21, 2014, the underwriters exercised in full their option to purchase 1,800,000 additional shares.

On February 3, 2015, the Company completed a private placement of $115,000,000 aggregate principal amount of 2.50% Convertible Senior Notes due 2022, or the 2022 Notes, to the investment bank acting as the initial purchaser who subsequently resold the 2022 Notes to qualified institutional buyers. The 2022 Notes are convertible at an initial conversion rate of 93.2945 shares of the Company’s common stock per $1,000 principal amount of the 2022 Notes, which is equal to an initial conversion price of approximately $10.72 per share of common stock (see Note 12 for more information).
Recent Accounting Pronouncements
In May 2014, the FASB issued Accounting Standards Update, or ASU, No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09), which creates a single source of revenue guidance under GAAP for all companies in all industries. The core principle of ASU 2014-09 is that revenue should be recognized in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 defines a five-step process in order to achieve this core principle, which may require the use of judgment and estimates. ASU 2014-09 also requires expanded qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and estimates used. ASU 2014-09 will be effective for the Company in the first quarter of fiscal 2017, and early adoption is not permitted. The Company may adopt ASU 2014-09 either by way of a full retrospective approach for all periods presented in the period of adoption or a modified retrospective approach. The Company is currently evaluating the impact that ASU 2014-09 will have on its financial statements and has not yet determined which transition method it will apply.
In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014-15). This update is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 requires management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. Specifically, the amendments: (1) provide a definition of the term substantial doubt; (2) require an evaluation every reporting period including interim periods; (3) provide principles for considering the mitigating effect of management’s plans; (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans; (5) require an express statement and other disclosures when substantial doubt is not alleviated; and (6) require an assessment for a period of one year after the date that the financial statements are issued (or available to be issued). ASU 2014-15 will be effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016, with early adoption permitted. ASU 2014-15 will be effective for the Company beginning with its annual report for fiscal 2016 and interim periods thereafter. The Company is currently evaluating the impact that ASU 2014-15 will have on its financial statements.

License_and_Collaboration_Agre

License and Collaboration Agreements	12 Months Ended
License and Collaboration Agreements	Dec. 31, 2014
License and Collaboration Agreements	2. License and Collaboration Agreements
	Indivior PLC
	In May 2014, the Company entered into an exclusive license agreement with Indivior, which became effective on June 19, 2014. Under the terms of this agreement, the Company granted to Indivior exclusive, world-wide rights to develop and commercialize AP Products for all indications, subject to its right of first negotiation with Indivior to collaborate to develop and commercialize AP Products for non-addiction indications. In exchange for these rights, the Company received an upfront, non-refundable cash payment of $20,000,000 in June 2014 and also received an additional $5,000,000 in July 2014 after delivery of specified materials to Indivior. The Company is also eligible to receive aggregate cash payments of up to $120,000,000 upon the achievement by Indivior of certain contingent event-based payments, of which $70,000,000 are regulatory and development-based and $50,000,000 are commercialization-based. In addition, the Company is entitled to receive tiered double-digit royalty payments of up to the mid-teens on a percentage basis on potential future net sales of the products in the United States, and high single-digit royalty payments on potential future net sales of the products outside the United States. The Company also agreed to transfer its existing AP Investigational New Drug applications, or INDs, know-how, and to provide supply transition assistance to facilitate the establishment of Indivior’s AP Product manufacturing capabilities pursuant to a mutually agreed supply transition plan.
	The Company assessed its transfer and assistance obligations under the Indivior agreement using the multiple-element arrangements revenue recognition guidance since those obligations involved more than one deliverable to Indivior. This analysis involved identification of the deliverables, determining if they qualify as separate units of accounting, arriving at fair value estimates for each separate unit of accounting, and allocating total consideration to each unit of accounting. The Company identified the following non-contingent deliverables under the license agreement: (1) grant of exclusive rights, or the license; (2) transfer of know-how necessary for the manufacture and development of AP Products; (3) transfer of INDs; (4) transfer of specified materials; and (5) supply of transition assistance to facilitate the establishment of Indivior’s AP Product manufacturing capabilities pursuant to a mutually agreed upon supply transition plan. The license, know-how, INDs and supply of transition assistance deliverables were combined into one unit of accounting since each of these deliverables was dependent on, and not separate from each other, and accordingly did not have stand-alone value. The materials represented the other unit of accounting. The total of the upfront cash payment of $20,000,000 and the additional cash payment of $5,000,000 were allocated into two units of accounting using the relative estimated selling price method. The Company developed its best estimate of selling prices for each deliverable in order to allocate the non-contingent arrangement consideration to the two units of accounting. For the license, know-how, INDs and supply of transition assistance, the Company used the discounted cash flow method to estimate the price at which it could sell them on a stand-alone basis. Embedded in the estimate were significant assumptions including: (1) probabilities of success during the development process; (2) potential customer market for the drug; (3) selling price for the drug; (4) costs to develop, maintain and manufacture the developed drug; and (5) discount rate. For the materials, the Company estimated the selling price based on the cost to purchase such materials from third party suppliers. Both the initial upfront cash payment of $20,000,000 and the additional cash payment of $5,000,000 were recognized as collaboration revenue upon the transfer of the deliverables to Indivior, which occurred in the third quarter of 2014.
	Astellas Pharma Inc.
	In December 2005, the Company entered into an agreement pursuant to which it licensed to Astellas Pharma Inc., exclusive rights to develop and commercialize gabapentin enacarbil in Japan, Korea, the Philippines, Indonesia, Thailand and Taiwan. Astellas commenced commercialization of gabapentin enacarbil in Japan, and began selling gabapentin enacarbil in July 2012 under the trade name of REGNITE^® (gabapentin enacarbil) Extended-Release Tablets. In May 2013, Astellas notified the Company that it did not have plans for the commercialization of gabapentin enacarbil in the five other Asian countries in its territory. As a result, in May 2013, the rights to gabapentin enacarbil in Korea, the Philippines, Indonesia, Thailand and Taiwan reverted to the Company. In the years ended December 31, 2014, 2013 and 2012, the Company recognized collaboration revenue of $1,134,000, $1,137,000 and $1,515,000, respectively, representing amortization of the up-front license payment under this agreement. In the year ended December 31, 2012, the Company also recognized a $10,000,000 milestone payment in connection with the approval of REGNITE in Japan. For the years ended December 31, 2014, 2013 and 2012, the Company recognized $561,000, $400,000 and $109,000, respectively, in royalty revenue. As of December 31, 2014, the Company had recognized an aggregate of $54,073,000 of revenue pursuant to this agreement. At December 31, 2014, $11,998,000 of revenue was deferred under this agreement and was being recognized on a straight-line basis over a period that the Company expects to remain obligated to provide services, of which $1,134,000 was classified within current liabilities and the remaining $10,864,000 was recorded as a noncurrent liability.
	Glaxo Group Limited
	Prior to the November 2012 termination and transition agreement (see Note 1 for more information), in January 2012, the Company provided notice to GSK of the Company’s belief that, among other matters, GSK had materially breached its contractual obligation. In February 2012, the Company and GSK commenced litigation. The November 2012 termination and transition agreement provided for a mutual release of claims and resolved all ongoing litigation between the parties (see Note 3 for more information).
	In February 2007, the Company entered into an exclusive collaboration agreement with GSK to develop and commercialize gabapentin enacarbil in all countries of the world excluding the Astellas territory. In November 2010, the Company amended and restated its collaboration agreement with GSK, pursuant to which the Company reacquired all rights to gabapentin enacarbil outside of the United States previously granted to GSK (which excludes the Astellas territory) and obtained the right, but not the obligation, to pursue development of HORIZANT for: (i) the potential treatment of diabetic peripheral neuropathy; (ii) the potential treatment of postherpetic neuralgia, or PHN, to the extent that a product label would reflect a superiority claim over a currently approved drug; and (iii) any additional indications in the United States. In April 2011, the FDA approved HORIZANT for the treatment of RLS in adults. Shipments of HORIZANT to wholesalers commenced in June 2011, and HORIZANT was commercially launched in July 2011. In June 2012, the FDA approved HORIZANT for the management of PHN in adults. Under the collaboration agreement, GSK remained responsible for further development and regulatory matters with respect to HORIZANT and manufacturing and commercialization of HORIZANT in the United States for all indications.
	In March 2007, GSK made an up-front, non-refundable license payment of $75,000,000. Under the terms of the amended and restated collaboration agreement, the Company received $130,000,000 in aggregate clinical and regulatory event-based payments that have been fully recognized through December 31, 2012, including $10,000,000 received and fully recognized in June 2012 in connection with the first commercial sale of HORIZANT for the management of PHN in adults. The Company concluded that the up-front license payment did not have value to GSK on a stand-alone basis without the benefit of the specified development activities that the Company performed in connection with HORIZANT and that $85,000,000 of milestones paid for clinical trial and pre-clinical activities were either not sufficiently substantive or not sufficiently at risk to be accounted for using the “when-earned” model. Accordingly, these milestones and the up-front payment were combined into one unit of accounting that was recognized over the development period to commercialization of the product, during which time delivery of substantially all of the efforts required for the completion of the Company’s contractual responsibilities under the GSK agreement occurred, and the Company determined that no additional performance obligations resulted from the amended agreement. As of December 31, 2012, the Company had recognized an aggregate of $205,000,000 of up-front license, milestone and contingent event-based payments pursuant to this agreement and no revenue was deferred under this agreement.
	The Company’s net revenue from unconsolidated joint operating activities from the GSK collaboration agreement was $0, $0 and $10,000,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	The following table presents the Company’s total revenues that have been recognized during the year indicated pursuant to its current license agreement with Astellas and Indivior and its terminated collaboration agreement with GSK (in thousands):


		Year Ended December 31,
		2014		2013		2012
	Astellas	$	1,695	$	1,537	$	11,624
	GSK		—		—		10,000
	Indivior		25,000		—		—

		$	26,695	$	1,537	$	21,624

Acquisitions_and_AcquisitionRe

Acquisitions and Acquisition-Related Items	12 Months Ended
Acquisitions and Acquisition-Related Items	Dec. 31, 2014
Acquisitions and Acquisition-Related Items	3. Acquisitions and Acquisition-Related Items
	On November 8, 2012, the Company reached an agreement with GSK to terminate the collaboration agreement dated November 7, 2010 between the Company and GSK (see Note 1 for more information on the termination and transition agreement and see Note 2 for more information on the terminated collaboration agreement).
	Pursuant to a separate stock purchase agreement entered into between the parties on November 8, 2012, GSK purchased $20,000,000 of common stock of the Company, or an aggregate of 1,841,112 shares at $10.863 per share, which per share price represented a 12.5 percent premium to the average of the closing prices of the Company’s common stock for the ten trading days prior to October 31, 2012. In addition, the Company was granted a Put Option that was exercisable for six months from November 9, 2012 to require GSK to purchase up to an additional $20,000,000 of common stock of the Company at a 12.5 percent premium to the average of the closing prices of the Company’s common stock for the ten trading days prior to the day the Company exercises this option. On November 9, 2012, the Company exercised the Put Option in full. The value of the Put Option was the difference between the price paid by GSK for the shares put, $20,000,000, and the value of the shares based on the Company’s closing stock price on the day of exercise. On November 9, 2012, pursuant to the exercise of the Put Option, GSK purchased an additional 2,190,100 shares at $9.132 per share.
	The Company accounted for the termination and transition agreement and the stock purchase agreement with GSK in accordance with the provisions of the Business Combinations topic of the Codification. Under the provisions of the Business Combinations topic, the acquisition date for a business is the date on which the Company obtains control of the acquiree. The Company obtained control of the HORIZANT business at the end of the transition period, or May 1, 2013. Accordingly, on November 8, 2012, the transaction did not meet the definition of a business combination, and the Company accounted for the transaction as a multiple-element arrangement consisting of the settlement of a pre-existing relationship in exchange for the right to acquire the HORIZANT business at the end of a defined transition period, the sale of common stock at a premium and the obligation by the Company to make certain cash payments to GSK in the future. The value of the HORIZANT business was based on an estimated discounted cash flow analysis attributable to the HORIZANT business.
	The following table summarizes the fair value of consideration exchanged as part of the termination and transition agreement (in thousands):


	Cash payable to GSK (recorded as “Other noncurrent liability” on the Company’s Balance Sheet for the year ended December 31, 2012)		$	2,314
	Issuance of common shares to GSK			30,268
	Cash received for common shares issued to GSK			(40,000	)
	Settlement of litigation with GSK			20,499
	Transaction costs			476

			$	13,557

	The components of the consideration transferred are described below:

		•		The cash payable to GSK represents the net present value of the annual payments to GSK of $1,000,000 for six years beginning in 2016.

		•		The Company recorded the issuance of common shares to GSK based on the Company’s closing stock prices on the respective stock issuance dates. The Company issued 1,841,112 and 2,190,100 common shares to GSK on November 8, 2012 and November 9, 2012, respectively.

		•		The termination and transition agreement provided for a mutual release of claims and resolved all ongoing litigation between the Company and GSK and effectively settled a preexisting relationship (see Note 1 for more information). As a result, the Company recorded a gain on the settlement of litigation, which represented foregone potential future monetary damages. This amount was valued based on a probability weighted scenario analysis that took into consideration the probability of each potential future alternative outcomes of the litigation between the parties.

		•		The transaction costs represent direct external costs incurred by the Company in connection with the November 2012 transaction.
	The consideration exchanged was recorded in the Company’s financial statements for the year ended December 31, 2012.
	On May 1, 2013, the Company obtained control of, and thus completed the acquisition of, the HORIZANT business. The acquisition constituted a business acquisition as defined under the provisions of the Business Combinations topic. Accordingly, the acquisition reflected the removal of the right to the HORIZANT business (which was recorded at fair value, as determined by a discounted cash flow analysis, that remained unchanged as of May 1, 2013), and the recording of the acquisition date fair values of the acquired inventory and manufacturing property and equipment assets. Assets acquired as a result of this transaction were as follows (in thousands):


	Inventories		$	11,733
	Manufacturing property and equipment			1,967

	Total assets acquired		$	13,700

	Inventories were comprised of acquired raw materials, specifically gabapentin enacarbil, and were valued using the cost approach. The cost approach provides a framework for estimating value based on the principle of substitution. The estimated fair value was calculated based on the costs to replace or reproduce the asset, including the cost of recrystallization of the raw material received, while considering any impact on the value of any obsolescence.
	Manufacturing property and equipment acquired included certain equipment and a dedicated manufacturing suite for use in the manufacture of HORIZANT and was recorded at fair value using the replacement cost method. The replacement cost method uses an estimate of the cost of replacing or reproducing an asset to measure value. This amount is then reduced to reflect the amount of depreciation that has accrued given the asset’s age. Other factors and adjustments were considered in concluding on the fair value, including obsolescence of the acquired assets. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the respective assets, which is ten years.
	In 2013, the Company incurred $476,000 in transaction costs related to the HORIZANT business acquisition, which primarily consisted of legal, accounting and valuation-related expenses. These expenses were recorded in the “Selling, general and administrative” line of the “Operating expenses” section of the Company’s statement of comprehensive loss.
	The following unaudited supplemental pro forma information summarizes the combined results of operations of the Company and the HORIZANT business as though the acquisition had occurred on January 1, 2012 (in thousands):


			Year Ended
			December 31,
			2013			2012
	Revenues		$	9,128		$	28,119
	Net loss		$	92,791		$	84,695
	These amounts have been calculated after applying the Company’s accounting policies and adjusting the results of the HORIZANT business to reflect the following adjustments:

		•		An amendment to depreciation expense included in costs of goods sold to reflect the depreciation of the fair value of the acquired manufacturing property and equipment over the estimated remaining useful lives of the respective assets.

		•		The difference between the cost of API that GSK incurred and the Company’s recorded fair value of the API.

		•		The difference in selling expense between GSK direct selling expenses and the Company’s third party contractual costs.
	The pro forma information presented above is for informational purposes only and is not indicative of the results of operations that would have been achieved if the acquisition had taken place at the beginning of January 2012, nor is it indicative of any future results.

Cash_and_Cash_Equivalents_Shor

Cash and Cash Equivalents, Short-Term Investments and Restricted Investments	12 Months Ended
	Dec. 31, 2014
Cash and Cash Equivalents, Short-Term Investments and Restricted Investments	4. Cash and Cash Equivalents, Short-Term Investments and Restricted Investments
	The following are summaries of cash and cash equivalents, short-term investments and restricted investments (in thousands):


			Cost			Gross			Gross				Estimated
						Unrealized			Unrealized				Fair Value
						Gains			Losses
	As of December 31, 2014:
	Cash		$	3,383		$	—		$	—			$	3,383
	Money market funds			8,576			—			—				8,576
	U.S. government-sponsored agencies			2,000			—			(2	)			1,998
	Corporate debt securities			88,127			12			(40	)			88,099
	Certificates of deposit			1,725			—			—				1,725

			$	103,811		$	12		$	(42	)		$	103,781

	Reported as:
	Cash and cash equivalents												$	11,958
	Short-term investments													90,098
	Restricted investments													1,725

													$	103,781

			Cost			Gross			Gross				Estimated
						Unrealized			Unrealized				Fair Value
						Gains			Losses
	As of December 31, 2013:
	Cash		$	2,281		$	—		$	—			$	2,281
	Money market funds			10,046			—			—				10,046
	U.S. government-sponsored agencies			2,500			—			—				2,500
	Corporate debt securities			43,831			6			(6	)			43,831
	Certificates of deposit			1,725			—			—				1,725

			$	60,383		$	6		$	(6	)		$	60,383

	Reported as:
	Cash and cash equivalents												$	20,584
	Short-term investments													38,074
	Restricted investments													1,725

													$	60,383

	At December 31, 2014 and 2013, the contractual maturities of all investments held were less than 16 months and one year, respectively. All investments have been designated as available-for-sale, and changes to unrealized gains and losses are reflected as the only component of accumulated other comprehensive loss. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company has classified all investments as short-term, even though the stated maturity may be one year or more beyond the current balance sheet date.
	No gross realized gains or losses were recognized in 2014, 2013 and 2012, and accordingly, there were no amounts reclassified out of accumulated other comprehensive loss to earnings in 2014, 2013 or 2012.

	The Company’s available-for-sale investments, which include cash equivalents and short-term investments, are measured at fair value on a recurring basis and are classified at the following fair value hierarchy (see Note 1 for the Company’s accounting policy on measuring fair value of financial instruments) (in thousands):


			Total As of			Fair Value Measurements at Reporting Date Using
			December 31,			Fair Value Measurements at Reporting Date Using
	Description		2014			Quoted Prices			Significant				Significant
						in Active			Other				Unobservable
						Markets			Observable				Inputs
						for Identical			Inputs				(Level 3)
						Assets			(Level 2)
						(Level 1)
	Money market funds		$	8,576		$	8,576		$	—			$	—
	U.S. government-sponsored agencies			1,998			—			1,998				—
	Corporate debt securities			88,099			—			88,099				—
	Certificates of deposit			1,725			—			1,725				—

	Total		$	100,398		$	8,576		$	91,822			$	—



		Total As of			Fair Value Measurements at Reporting Date Using
		December 31,			Fair Value Measurements at Reporting Date Using
Description		2013			Quoted Prices			Significant				Significant
					in Active			Other				Unobservable
					Markets			Observable				Inputs
					for Identical			Inputs				(Level 3)
					Assets			(Level 2)
					(Level 1)
Money market funds		$	10,046		$	10,046		$	—			$	—
U.S. government-sponsored agencies			2,500			—			2,500				—
Corporate debt securities			43,831			—			43,831				—
Certificates of deposit			1,725			—			1,725				—

Total		$	58,102		$	10,046		$	48,056			$	—

Property_and_Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Dec. 31, 2014
Property and Equipment	5. Property and Equipment, net
	Property and equipment at December 31, 2014 and 2013 consisted of the following (in thousands):


		December 31,
		2014			2013
	Laboratory equipment	$	10,561		$	10,701
	Manufacturing property and equipment		1,975			1,967
	Furniture and fixtures		1,076			1,107
	Computer equipment and software		5,656			5,475
	Leasehold improvements		3,405			3,344

			22,673			22,594
	Less: Accumulated depreciation and amortization		(20,251	)		(20,042	)

	Property and equipment, net	$	2,422		$	2,552

Other_Accrued_Liabilities

Other Accrued Liabilities	12 Months Ended
Other Accrued Liabilities	Dec. 31, 2014
Other Accrued Liabilities	6. Other Accrued Liabilities
	Other accrued liabilities at December 31, 2014 and 2013 were as follows (in thousands):


		December 31,
		2014		2013
	Accrued product costs	$	2,009	$	1,903
	Accrued selling and marketing expenses		1,210		883
	Accrued general and administrative expenses		466		632
	Accrued rebates, allowances and returns		986		315
	Other liabilities		446		205

	Total other accrued liabilities	$	5,117	$	3,938

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies	7. Commitments and Contingencies

	Operating Leases

	In February 2008, the Company entered into a lease for approximately 59,000 square feet of office space at 3400 Central Expressway, Santa Clara, California, the 3400 Lease. The term of the 3400 Lease extended to August 2013, which was 60 months from the date the premises were considered ready for occupation by the Company.

	Also in February 2008, the Company amended its lease with respect to the Company’s current office space at 3410 Central Expressway, Santa Clara, California, or, as amended, the 3410 Lease, that commenced in December 2001. This amendment extended the term of the 3410 Lease for approximately two years from the original expiration date of December 10, 2011, so that the 3410 Lease would expire in August 2013, on the same date as the 3400 Lease.

	In October 2012, the Company further amended the 3410 Lease to extend the term for an additional two years, so that the 3410 Lease would expire on August 27, 2015. In November 2014, the Company further amended the 3410 Lease to extend the term for an additional nine months, so that the 3410 Lease will expire on May 31, 2016.

	In connection with the 3410 Lease, the Company entered into a letter of credit agreement of $1,500,000 in December 2006. The fair value of the certificate of deposit is presented as restricted investments on the balance sheet at $1,500,000 as of December 31, 2014 and 2013. This letter of credit is required until the termination of the lease.

	The Company recognized rent expense on a straight-line basis over the applicable lease terms. Rent expense was $2,615,000, $2,626,000 and $3,185,000 for the years ended December 31, 2014, 2013 and 2012, respectively. Deferred rent asset of $180,000 and $477,000 at December 31, 2014 and 2013, respectively, represented the difference between rent expense recognized and actual cash payments related to the Company’s operating leases. At December 31, 2014, deferred rent was comprised of a current deferred rent asset of $127,000 and a noncurrent deferred rent asset of $53,000. At December 31, 2013, deferred rent was comprised of a current deferred rent asset of $308,000 and a noncurrent deferred rent asset of $169,000.

	At December 31, 2014, future minimum payments under the Company’s non-cancelable operating lease were as follows (in thousands):



	Year ending December 31:
	2015	$	2,368
	2016		986

	Total minimum lease payments	$	3,354




	Guarantees and Indemnifications

	The Company, as permitted under Delaware law and in accordance with its bylaws, indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity. The term of the indemnification period is for the officer’s or director’s lifetime. The Company may terminate the indemnification agreements with its officers and directors upon 90 days’ written notice, but termination will not affect claims for indemnification relating to events occurring prior to the effective date of termination. The maximum amount of potential future indemnification is unlimited; however, the Company has a director and officer insurance policy that limits its exposure and may enable it to recover a portion of any future amounts paid. The Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company had not recorded any liabilities for these agreements as of December 31, 2014.

Stockholders_Equity

Stockholders' Equity

12 Months Ended

Dec. 31, 2014

Stockholders' Equity

8. Stockholders’ Equity

Common Stock

At December 31, 2014 and 2013, the Company was authorized to issue 100,000,000 shares of common stock. On January 29, 2014, the Company completed an underwritten public offering of 12,000,000 shares of its common stock at a price to the public of $6.00 per share. Net cash proceeds from the public offering were $67,300,000, after deducting the underwriting discounts and commissions and offering expenses payable by the Company. On February 21, 2014, the underwriters exercised in full their option to purchase 1,800,000 additional shares resulting in additional net cash proceeds of $10,100,000, after deducting the underwriting discounts and commissions and offering expenses payable by the Company.

Stockholders’ Rights Plan

On December 16, 2005, the Company adopted a preferred stock rights plan pursuant to which each share of the Company’s common stock outstanding has attached to it a preferred stock purchase right, or a right, that confers the right to purchase one one-hundredth of a share of Series A junior participating preferred stock at an exercise price of $140.00 per right, subject to adjustment, and will be exercisable only if a person or group acquires beneficial ownership of 15% or more of the Company’s common stock or announces a tender offer for 15% or more of the Company’s common stock. If such a person acquires 15% or more of the Company’s common stock, all rights holders, except such person, will be entitled to acquire the Company’s common stock at a discount through the exercise of the right. The rights plan has been designed to discourage acquisitions of more than 15% of the Company’s common stock without negotiations with the board of directors. The rights expire on January 13, 2016. The rights trade with the Company’s common stock, unless and until they are separated upon the occurrence of certain future events. The board of directors may terminate the rights plan at any time or redeem the rights prior to the time the rights are triggered.

Equity Incentive Plans

On June 11, 2014, the Company’s stockholders approved the 2014 Equity Incentive Plan, or the 2014 Plan. The 2014 Plan is intended to be the successor to the 2005 Equity Incentive Plan, the 2005 Non-Employee Directors’ Stock Option Plan and the 2010 Inducement Award Plan, collectively referred to as the Prior Plans. All outstanding stock awards granted under the Prior Plans will continue to be subject to the terms and conditions as set forth in the agreements evidencing such stock awards.

1999 Stock Plan

Under the terms of the 1999 Stock Plan, or the 1999 Plan, options or stock purchase rights were granted by the board of directors to employees, directors and consultants. Options granted were either incentive stock options or non-statutory stock options. Incentive stock options were granted to employees with exercise prices of no less than the fair value, and non-statutory options were granted to employees, directors or consultants at exercise prices of no less than 85% of the fair value of the common stock on the grant date as determined by the board of directors. Options vested as determined by the board of directors, generally at the rate of 25% at the end of the first year, with the remaining balance vesting ratably over the next three years for initial employee grants and ratably over four years for subsequent grants. Options granted under the 1999 Plan expire no more than ten years after the date of grant. All options granted under the 1999 Plan have vested.

2005 Equity Incentive Plan

In January 2005, the Company’s board of directors adopted the 2005 Equity Incentive Plan, or the 2005 Plan. Under the terms of the 2005 Plan, options vest as determined by the board of directors, generally at the rate of 25% at the end of the first year, with the remaining balance vesting ratably over the next three years for initial employee grants and ratably over four years for subsequent grants. Options granted under the 2005 Plan expire no more than ten years after the date of grant.

In January 2007, the Company’s board of directors approved the use of grants of restricted stock units to employees, directors or consultants under the 2005 Plan as part of the Company’s long-term incentive compensation program. Restricted stock units have no exercise price, are valued using the closing market price on the date of grant and vest as determined by the board of directors, typically either: (i) in annual tranches over a four-year period at the rate of 25% at the end of each year; (ii) in annual tranches over a three-year period at the rate of 25%, 25% and 50%, respectively, at the end of each year; (iii) in annual tranches over a three-year period at 50% on the second anniversary and 50% on the third year anniversary; or (iv) in one tranche on the one-year anniversary of the grant date. Employees can elect to have the Company withhold a portion of shares to pay for their payroll taxes in connection with the vesting of restricted stock units, where the Company would then make a cash payment for the associated payroll taxes on behalf of the employees, or employees can elect to make the cash payment for the associated payroll taxes.

In May 2010, the Company granted performance stock unit awards to two executive employees under the 2005 Plan. Each performance stock unit award was scheduled to vest three years from the grant date, with the actual number of shares of common stock of the Company subject to issuance to be between 0% and 200% of the target amount, based on the performance of the Company’s total shareholder return as compared to the total shareholder returns of a group of pre-selected pharmaceutical companies over a performance period ending on the third anniversary of the grant date. The target amount of shares of common stock of the Company that were subject to issuance under the performance stock unit awards was 140,000, and the grant date fair value using a lattice valuation model of these performance stock unit awards was $2,675,000. In 2010, a performance stock unit award representing a target amount of 40,000 shares was cancelled due to the departure of one of the two executive employees. In 2013, 97,300 shares were cancelled based on the performance of the Company’s total shareholder return as compared to the total shareholder returns of a group of pre-selected pharmaceutical companies over the three year performance period. At December 31, 2014 and 2013, there were no shares subject to these performance stock unit awards, and the associated expense recognized in the year ended December 31, 2014, 2013 and 2012 was $0, $232,000 and $638,000, respectively.

In February 2014, the Company granted performance stock options to its executive officers under the 2005 Plan. Each performance stock option is subject to two, equally weighted, performance conditions. One performance condition relates to the achievement of a pre-determined development criteria and the other relates to achievement of a pre-determined revenue criteria. Each performance stock option vests, if at all, upon achievement of the respective performance condition during a performance period ending on December 31, 2015. Shares associated with each performance condition vest 50% upon achievement of the performance condition, with the remaining 50% to vest on the one-year anniversary date of the initial vest date. The target amount of shares of common stock that are subject to issuance under these performance stock options was 316,000, and the grant date fair value using a Black-Scholes valuation model of these performance stock options was $1,334,000. During the year ended December 31, 2014, the Company recognized $445,000 in expense associated with these performance stock options.

Under the terms of the 2005 Plan, the maximum number of shares that may be issued shall not exceed the total of 2,000,000, plus any shares issuable from options previously granted from the 1999 Plan at the date of the Company’s initial public offering, plus an annual increase equal to the lesser of (i) 2.5% of the total number of common shares outstanding at the end of the preceding calendar year and (ii) 2,000,000 common shares. During the year ended December 31, 2014, the annual increase to the 2005 Plan reserve was 1,195,009 shares. In June 2014, in connection with the Company’s adoption of the 2014 Equity Incentive Plan, or the 2014 Plan, described below, no further awards may be granted under the 2005 Plan. Although the 2005 Plan has terminated, all outstanding options under the 2005 Plan will continue to be governed by their existing terms.

2005 Non-Employee Directors’ Stock Option Plan

In January 2005, the Company’s board of directors adopted the 2005 Non-Employee Directors’ Stock Option Plan, or the 2005 Directors’ Plan, under which non-statutory options are automatically granted to non-employee directors.

Before May 1, 2012, any individual who first became a non-employee director automatically received an option to purchase 25,000 shares subject to vesting in four equal successive annual installments. From May 1, 2012 to June 10, 2014, any individual who first became a non-employee director automatically received an option to purchase 30,000 shares subject to vesting in 24 successive equal monthly installments. Prior to May 1, 2012, non-employee directors serving on the date of each annual meeting of stockholders received an option to purchase 10,000 shares subject to vesting in 12 successive equal monthly installments measured from the grant date. From May 1, 2012 to June 10, 2014, non-employee directors serving on the date of each annual meeting of stockholders received an option to purchase 15,000 shares subject to vesting in 12 successive equal monthly installments measured from the grant date. Stock options were granted at exercise prices no less than the fair value on the grant date and expired no more than ten years after the date of grant. In addition, from May 1, 2012 to June 10, 2014, any individual who served as a non-employee director on the date of each annual meeting received a restricted stock unit award of 5,000 shares. These restricted stock unit awards vest in full on the one-year anniversary of the grant date.

Under the terms of the 2005 Directors’ Plan, the maximum number of shares that may be issued shall not exceed the total of 150,000, plus an annual increase equal to the excess of (i) the number of shares subject to options granted in the preceding calendar year, over (ii) the number of shares added back to the share reserve from cancellations, provided that such increase shall not exceed 150,000 shares. During the year ended December 31, 2014, the annual increase to the 2005 Directors’ Plan reserve was 120,000 shares. In June 2014, in connection with the Company’s adoption of the 2014 Plan described below, no further awards may be granted under the 2005 Directors’ Plan. Although the 2005 Directors’ Plan has terminated, all outstanding options under the 2005 Directors’ Plan will continue to be governed by their existing terms.

New Employee Inducement Stock Awards

In May 2008, the Company’s then Senior Vice President and Chief Commercialization Officer was granted a new employee inducement stock award outside of the Company’s stockholder-approved equity plans consisting of nonqualified stock options to purchase 140,612 shares of the Company’s common stock. The stock options have a per share exercise price of $42.59, the closing trading price of the Company’s common stock on the NASDAQ Global Market on the May 1, 2008 grant date. The stock options have a ten-year term and vested over four years, with 25% cliff vesting on the first anniversary of the May 1, 2008 grant date, and 1/48th of the shares subject to the options vesting monthly thereafter. The Company also granted to the Company’s Senior Vice President and Chief Commercialization Officer a new employee inducement stock award outside of the Company’s stockholder-approved equity plans consisting of restricted stock units for 10,000 shares of the Company’s common stock. The restricted stock units vested in four equal annual installments on each anniversary of the May 1, 2008 grant date.

2010 Inducement Award Plan

In May 2010, the Company’s board of directors adopted the 2010 Inducement Award Plan, or the 2010 Inducement Plan. Under the terms of the 2010 Inducement Plan, options vest as determined by the board of directors or the compensation committee of the board of directors, generally at the rate of 25% at the end of the first year, with the remaining balance vesting ratably over the next three years. Options granted under the 2010 Inducement Plan expire no more than ten years after the date of grant. Restricted stock units have no exercise price, are valued using the closing market price on the date of grant and vest as determined by the board of directors or the compensation committee of the board of directors, typically in annual tranches over a four-year period at the rate of 25% at the end of each year.

A total of 350,000 shares of common stock were initially authorized for issuance under the 2010 Inducement Plan, and an additional 625,000 shares were authorized for issuance in 2011. Under the terms of the 2010 Inducement Plan, the maximum number of shares that may be issued shall not exceed the total of 975,000. In June 2014, in connection with the Company’s adoption of the 2014 Plan described below, no further awards may be granted under the 2010 Inducement Plan. Although the 2010 Inducement Plan has terminated, all outstanding options under the 2010 Inducement Plan will continue to be governed by their existing terms.

2014 Equity Incentive Plan

The terms of the 2014 Plan provide for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, other stock awards and performance awards that may be settled in cash, stock or other property, that may be granted by the board of directors or the independent compensation committee of the board of directors. Options granted may be either incentive stock options or non-statutory stock options. Incentive stock options may be granted to employees with exercise prices of no less than the fair value, and non-statutory options may be granted to employees, directors or consultants at exercise prices of no less than fair value, of the common stock on the grant date. Options vest as determined by the board of directors or the compensation committee of the board of directors, generally at the rate of 25% at the end of the first year, with the remaining balance vesting ratably over the next three years. Options granted under the 2014 Plan expire no more than ten years after the date of grant. The terms of the 2014 Plan also provides for the grant of restricted awards, which have no exercise price, are valued using the closing market price on the date of grant and vest as determined by the board of directors or the compensation committee of the board of directors, typically in annual tranches over a four-year period at the rate of 25% at the end of each year. The 2014 Plan also provides for the grant of performance stock or cash awards that may vest or become payable upon the attainment of pre-determined performance goals during a performance period.

Under the terms of the 2014 Plan, any individual who first becomes a non-employee director automatically receives an option to purchase 30,000 shares subject to vesting in 24 successive equal monthly installments. Non-employee directors serving on the date of each annual meeting of stockholders receives an option to purchase 15,000 shares subject to vesting in 12 successive equal monthly installments measured from the grant date. Stock options are granted at exercise prices no less than the fair value on the grant date and expire no more than ten years after the date of grant. In addition, any individual who serves as a non-employee director on the date of each annual meeting receives a restricted stock unit award of 5,000 shares. These restricted stock unit awards vest in full on the earlier of: (1) the one-year anniversary of the grant date or (2) the date of the next annual meeting following the grant date.

The total number of shares of the Company’s common stock available for issuance under the 2014 Plan is initially 4,471,059 shares plus up to an additional 7,847,852 Returning Shares (as defined below) as such shares become available from time to time. “Returning Shares” means the shares subject to outstanding awards granted under the Prior Plans and the 1999 Stock Plan that, from and after the effective date of the 2014 Plan: (a) expire or terminate for any reason prior to exercise or settlement; (b) are forfeited, cancelled or otherwise returned to the Company because of the failure to meet a contingency or condition required for the vesting of such shares; or (c) other than with respect to outstanding stock options and stock appreciation rights granted under the Prior Plans or the 1999 Stock Plan with an exercise or strike price of at least 100% of the fair market value of the underlying Company common stock on the date of grant, are reacquired or withheld (or not issued) by the Company to satisfy a tax withholding obligation in connection with a stock award. Eligible participants under the 2014 Plan include the Company’s employees and directors, including the Company’s executive officers and consultants. At December 31, 2014, there were 4,479,789 shares remaining and available for future grant under the 2014 Plan.

A summary of option activity as of and for the year ended December 31, 2014 is presented below:

Weighted-

Aggregrate

Average

Intrinsic Value

Exercise

Remaining

Price

Contractual

Term

(In Thousands)

Outstanding at January 1, 2014

5,368,964

16.81

Options granted

1,986,620

6.12

Options cancelled

(437,453

)

11.6

Options exercised

(289,519

)

4.49

Outstanding at December 31, 2014

6,628,612

14.49

5.86

(8,283

)

Exercisable at December 31, 2014

4,504,585

18.26

4.45

(3,427

)

A summary of restricted stock unit activity for the year ended December 31, 2014 is presented below:

Weighted-

Average

Grant Date

Fair Value

Outstanding at January 1, 2014

1,455,190

7.15

Awards granted

394,790

6.07

Awards cancelled

(188,500

)

6.87

Awards vested

(640,136

)

7.27

Outstanding at December 31, 2014

1,021,344

6.7

The weighted-average grant date fair values of options granted in the years ended December 31, 2014, 2013 and 2012 were $4.05, $5.22 and $3.12 per share, respectively. The weighted-average grant date fair values of restricted stock units granted in the years ended December 31, 2014, 2013 and 2012 were $6.07, $8.13 and $5.22 per share, respectively.

The aggregate intrinsic value of all options outstanding and exercisable at December 31, 2014 was based on a closing stock price of $8.77.

The total intrinsic value of options exercised in the years ended December 31, 2014, 2013 and 2012 was $758,000, $304,000 and $137,000, respectively. The total fair value of options that vested in the years ended December 31, 2014, 2013 and 2012 was $4,572,000, $4,786,000 and $8,107,000, respectively. The total fair value of restricted stock units that vested in the years ended December 31, 2014, 2013 and 2012 was $4,656,700, $6,202,000 and $4,372,000, respectively.

As of December 31, 2014, the total compensation cost related to 2,124,027 unvested options and unvested awards covering 1,021,344 shares not yet recognized was $11,616,000. This amount will be recognized over an estimated weighted-average amortization period of 2.41 years.

Employee Stock Purchase Plan

As of December 31, 2014, the Company had reserved a total of 1,445,555 shares of common stock for issuance under the ESPP. In addition, the board of directors may increase the share reserve as of each January 1 through January 1, 2015, by an amount not to exceed the lesser of (i) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year or (ii) 250,000 shares. The ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. The price at which the stock is purchased is equal to the lower of 85% of the fair market value of the common stock at the beginning of an offering period or after a purchase period ends. During the years ended December 31, 2014, 2013 and 2012, 227,720, 142,455 shares and 185,249 shares, respectively, were purchased under the ESPP. During the year ended December 31, 2014, the annual increase to the ESPP was 250,000 shares. At December 31, 2014 and 2013, there were 277,882 and 255,602 shares, respectively, remaining and available for future grant under the ESPP.

Warrants

At December 31, 2014 and 2013, 0 and 283,420 warrants were outstanding and exercisable for shares of common stock at $25.40 per share, respectively.

Preferred_Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2014
Preferred Stock	9. Preferred Stock
	At December 31, 2014 and 2013, the Company was authorized to issue 5,000,000 shares of preferred stock, of which 1,000,000 shares were authorized for issuance as Series A junior participating preferred stock.

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2014
Income Taxes	10. Income Taxes

	Deferred income taxes reflect the net tax effects of net operating loss, or NOL, and tax credit carryovers and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s net deferred tax assets were as follows (in thousands):



		December 31,
		2014			2013
	Net operating loss carryforwards	$	182,791		$	161,663
	Research credit carryforwards		31,249			30,111
	Capitalized research and development		3,760			5,579
	Deferred revenue		4,824			4,700
	Stock awards		16,901			14,672
	Other		3,043			1,605

	Total net deferred tax assets		242,568			218,330
	Valuation allowance		(242,568	)		(218,330	)

	Net deferred tax assets	$	—		$	—


	Realization of net deferred tax assets is dependent upon the Company generating future taxable income, the timing and amount of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $24,238,000, $27,210,000 and $6,259,000 during 2014, 2013 and 2012, respectively.

	As of December 31, 2014, the Company had NOL carryforwards for federal income tax purposes of $463,798,000, which expire in the years 2022 through 2034, and federal research and development tax credits of $24,022,000, which expire in the years 2021 through 2034.

	As of December 31, 2014, the Company had NOL carryforwards for state income tax purposes of $367,492,000, which expire in the years 2015 through 2034, and state research and development tax credits of $12,507,000, which do not expire.

	Approximately $529,000 of the valuation allowance for net deferred tax assets relates to benefits of stock option deductions that, when recognized, will be allocated directly to additional paid-in capital.

	The Company files income tax returns in the U.S. federal jurisdiction and various state jurisdictions. To date, the Company has not been audited by the Internal Revenue Service or any state income tax jurisdiction. Tax years 2000 to 2014 remain subject to examination by the U.S. federal jurisdiction and various state jurisdictions.

	Utilization of the Company’s NOL and credit carryforwards may be subject to substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Such annual limitation could result in the expiration of the NOL and credit carryforwards before utilization. As of December 31, 2014, based on the analyses performed on annual limitation as a result of ownership changes that may have occurred from inception through December 2014, the Company expects to be able to use all of its NOL and tax credit carryforwards.



	The Company’s unrecognized tax benefits relate to state research and development tax credits claimed on the Company’s state tax returns. The state research and development tax credits have not been utilized, are fully offset by a valuation allowance and currently have no tax impact.

	A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is as follows (in thousands):



	January 1, 2013	$	—
	Increases related to prior year tax positions		1,340

	December 31, 2013		1,340
	Increases related to currrent year tax positions		50

	December 31, 2014	$	1,390

Quarterly_Financial_Data_Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
Quarterly Financial Data (Unaudited)	Dec. 31, 2014
Quarterly Financial Data (Unaudited)	11. Quarterly Financial Data (Unaudited)

	The following table summarizes the unaudited quarterly financial data for the last two fiscal years (in thousands, except per share data):



			Quarter Ended
			Dec. 31,			Sept. 30,		June 30,			March 31,			Dec. 31,			Sept. 30,			June 30,			March 31,
			2014			2014(1)		2014			2014			2013			2013			2013			2013
	Selected Quarterly Data:
	Total revenues		$	7,091		$	31,068	$	5,334		$	3,375		$	2,879		$	2,527		$	2,086		$	459

	Gross profit(2)		$	6,143		$	5,088	$	4,321		$	2,527		$	2,121		$	1,732		$	1,391		$	—

	Net income (loss)		$	(17,657	)	$	8,259	$	(19,387	)	$	(20,548	)	$	(19,138	)	$	(18,816	)	$	(24,381	)	$	(23,548	)

	Basic and diluted net income (loss) per share		$	(0.28	)	$	0.13	$	(0.31	)	$	(0.36	)	$	(0.40	)	$	(0.39	)	$	(0.51	)	$	(0.50	)



	-1	Total revenues and net income was primarily from the recognition of $25,000,000 in collaboration revenue resulting from the Indivior licensing agreement (see Note 2 for more information).


	-2	Gross profit relates solely to HORIZANT product sales.

Subsequent_Events

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2014
Subsequent Events	12. Subsequent Events

	In February 2015, the Company completed a private placement of $115,000,000 principal amount of 2022 Notes. Interest on the 2022 Notes will be payable semi-annually in cash in arrears on February 1 and August 1 of each year, beginning on August 1, 2015, at a rate of 2.50% per year. The 2022 Notes mature on February 1, 2022, unless earlier converted or repurchased. The 2022 Notes are not redeemable prior to the maturity date. The 2022 Notes are convertible at an initial conversion rate of 93.2945 shares of our common stock per $1,000 principal amount of the 2022 Notes, subject to adjustment, which is equal to an initial conversion price of approximately $10.72 per share of common stock. Upon conversion, the 2022 Notes may be settled in shares of the Company’s common stock, together with a cash payment in lieu of delivering any fractional share. The conversion rate will be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, the Company will increase the conversion rate for a holder who elects to convert its 2022 Notes in connection with such a corporate event in certain circumstances. If the Company undergoes a fundamental change, which would include specified change of control transactions, or liquidation or dissolution or its common stock ceasing to be listed or quoted on specified national securities exchanges, and the fundamental change occurs prior to the maturity date of the 2022 Notes, holders of the 2022 Notes may require the Company to repurchase all or part of their 2022 Notes at a repurchase price equal to 100% of the principal amount of the 2022 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.



	On January 29, 2015, the Company entered into Amendment No. 1 to Rights Agreement, originally entered into on December 15, 2005, with Computershare Inc., successor rights agent to Computershare Shareowner Services LLC (f/k/a Mellon Investor Services LLC), as rights agent. This Amendment is entered in connection with the 2022 Notes offering described above and accommodates the structure of a “blocker” in the 2022 Notes such that no holder of the 2022 Notes will be entitled to receive shares of the Company’s common stock deliverable upon conversion of the 2022 Notes to the extent that such receipt would cause the holder to become, directly or indirectly, the “beneficial owner” (as defined in the 2022 Notes) of more than 14.99% of the shares of the Company’s common stock outstanding at such time.

Organization_and_Summary_of_Si1

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Basis of Preparation	Basis of Preparation
Basis of Preparation	The Company’s financial statements are prepared in accordance with the Financial Accounting Standards Board, or FASB, Accounting Standards Codification, or the Codification, which is the single source of authoritative U.S. generally accepted accounting principles, or GAAP.
Use of Estimates	Use of Estimates
Use of Estimates	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from these estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents and short-term investments, restricted investments, accounts receivables and accounts payables, approximate their fair value due to their short-term maturities. The Company accounts for the fair value of its financial instruments in accordance with the provisions of the Fair Value Measurement topic of the Codification.
	Fair value is the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The Company applies the market approach valuation technique for fair value measurements on a recurring basis and attempts to maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. All of the Company’s cash equivalents and short-term investments are measured using inputs classified at Level 1 or Level 2 within the fair value hierarchy. Level 1 inputs are quoted prices in active markets for identical assets. Level 2 inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Level 3 inputs are unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes and market reference data.
Cash Equivalents and Short-Term Investments	Cash Equivalents and Short-Term Investments
	The Company considers all highly liquid investments with original maturities of 90 days or less at the time of purchase to be cash equivalents, which primarily consist of money market funds, U.S. government-sponsored agencies and corporate debt securities.
	Management determines the appropriate classification of securities at the time of purchase. All investments have been designated as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company has classified all investments as short-term, even though the stated maturity may be one year or more beyond the current balance sheet date. Available-for-sale securities are carried at estimated fair value with unrealized gains and losses reported as a component of other comprehensive loss in the statements of comprehensive loss.
	The cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities, if any, are recorded in interest income and expense. The cost of securities sold is based on the specific-identification method. Interest and dividends are included in interest income.
Restricted Investments	Restricted Investments
	Under a facilities operating lease agreement, the Company is required to secure a letter of credit with cash or securities. At December 31, 2014 and 2013, the Company recorded $1,500,000 of restricted investments related to the letter of credit (see Note 7 for more information). The $1,500,000 was classified as restricted investments in the accompanying balance sheets at both December 31, 2014 and 2013.

	In connection with the Company’s license to use radioactive materials in its research facilities, it must maintain a $225,000 letter of credit with the Radiological Health Branch of the State of California. This requirement has been fulfilled through certificates of deposit with a financial institution. The fair value of the secured amount of $225,000 was classified as restricted investments in the accompanying balance sheets at both December 31, 2014 and 2013.
Segment Information	Segment Information
Segment Information	The Company operates in one operating segment, which is the development and commercialization of product candidates for the potential treatment of neurological and other disorders, and has operations solely in the United States. To date, all of the Company’s revenues from product sales are related to sales of HORIZANT in the United States. The Company also has recognized upfront and milestone payments and royalty revenue from its partnership with Astellas Pharma Inc. and recognized upfront and additional payments from its partnership with Indivior (see Note 2 for more information on these arrangements).
Concentrations of Risk	Concentrations of Risk
	The Company invests cash that is not being used for operational purposes. This exposes the Company to credit risk in the event of default by the institutions holding the cash and cash equivalents and available-for-sale securities to the extent of the amounts on its balance sheets. The credit risk is mitigated by the Company’s investment policy, which allows for the purchase of low risk debt securities issued by the U.S. government, U.S. government-sponsored agencies and highly rated banks and corporations, subject to certain concentration limits. The maturities of these securities are maintained at no longer than 16 months. The Company believes its established guidelines for investment of its excess cash enhances safety and liquidity through its policies on diversification and investment maturity.
	Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and available-for-sale investment securities in high-credit quality debt securities issued by the U.S. government, U.S. government-sponsored enterprises and highly rated banks and corporations. The carrying amounts of cash equivalents and available-for-sale investment securities are stated at fair value.
	The Company is subject to credit risk from its accounts receivable related to product sales. The Company’s trade accounts receivable arises from product sales in the United States. Three wholesale distributors represented 41%, 28% and 26%, respectively, of product sales for the year ended December 31, 2014. These three customers individually comprised 48%, 26% and 22%, respectively, of accounts receivable as of December 31, 2014. Three wholesale distributors represented 47%, 33% and 16%, respectively, of product sales for the year ended December 31, 2013. These three customers individually comprised 45%, 29% and 22%, respectively, of product sales related to accounts receivable as of December 31, 2013. To date, the Company has not experienced any losses with respect to the collection of its accounts receivable and believes that its accounts receivable are collectible.
	The Company relies on a single third-party contract manufacturer organization to manufacture HORIZANT.
Property and Equipment	Property and Equipment
Property and Equipment	Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the respective assets, which is generally five to ten years for the Company’s laboratory equipment, furniture and fixtures and manufacturing property and equipment and generally three years for the Company’s computer equipment and software. Leasehold improvements are amortized over their estimated useful lives or the remaining lease term, whichever is shorter.
Revenue Recognition	Revenue Recognition
	Product Sales
	The Company began selling HORIZANT to wholesalers in May 2013 following the return of the Company’s commercial rights from GSK. The Company recognizes revenue from HORIZANT product sales when there is persuasive evidence that an arrangement exists, delivery to the customer has occurred, the price is fixed or determinable and collectability is reasonably assured. Revenue from product sales is recorded net of estimated allowances for customer incentives such as cash discounts for prompt payment, distributor fees, expected returns, as appropriate (which are based on an analysis of historical return rates and deductions of HORIZANT, since its commercial launch by GSK in the second quarter of 2011), government rebates such as Medicaid reimbursements and patient assistance programs. Calculating certain of these items involves estimates and judgments based on contractual terms, historical utilization rates data for HORIZANT and new information regarding changes in these programs’ regulations and guidelines that would impact the amount of the actual rebates, the Company’s expectations regarding future utilization rates for these programs and channel inventory data. If future actual results vary from the Company’s estimates, the Company may need to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustment.
	Items Deducted from Gross Product Sales
	Prompt Pay Discount
	The Company offers cash discounts to its customers, generally 2% of the sales price, as an incentive for prompt payment. Based on the Company’s and GSK’s commercialization experience, the Company expects customers to continue to comply with the prompt payment terms to earn the cash discount as the Company is selling HORIZANT to the same customers under similar prompt payment terms and conditions. The Company estimates cash discounts for prompt payment based on contractual terms, GSK’s historical customer utilization rates and the Company’s historical customer utilization rates. The Company accounts for cash discounts by reducing accounts receivable by the full amount and recognizing the discount as a reduction of revenue in the same period the related revenue is recognized.
	Distributor Fees
	Under the Company’s inventory management agreements with significant wholesalers, the Company pays the wholesalers a fee primarily for distribution services as well as the maintenance of inventory levels. These distributor fees are based on a contractually determined fixed percentage of sales. The Company accrues the contractual amount and recognizes the discount as a reduction of revenue in the same period the related revenue is recognized.
	Product Returns
	The Company does not provide its customers with a general right of product return, but permits returns if the product is damaged or defective when received by the customer, or if the product has or is nearly expired. HORIZANT tablets currently have a shelf-life of 36 months from the date of manufacture. The Company will accept returns for products that will expire within six months or that have expired up to one year after their expiration dates. The Company obtained actual return history classified by the reasons for returns from GSK since GSK’s product launch in 2011, which provides a basis to reasonably estimate the Company’s future product returns. The Company estimates returns taking into consideration Company-specific adjustments to GSK’s returns history, the Company’s returns history, the shelf life of product, shipment and prescription trends and estimated distribution channel inventory levels.
	Government Rebates and Chargebacks
	The Company participates in a number of government rebate programs, such as the Medicaid Drug Rebate Program that provides assistance to eligible low-income patients based on each individual state’s guidelines regarding eligibility and services, Public Health Services or 340b programs, and the Medicare Part D Coverage Gap Discount Program, which provides rebates on prescriptions that fall within the “donut hole” coverage gap; and the Department of Veterans Affairs that offers discounts to authorized users of HORIZANT. HORIZANT is also listed on the Federal Supply Schedule, or FSS, of the General Services Administration which provides a discount to the Department of Defense, Department of Veterans Affairs, and TriCare. The Company estimates reductions to the Company’s revenues for government rebate programs based on product pricing, current rebates, GSK’s historical utilization rates, the Company’s actual utilization rates, new information regarding changes in these programs’ regulations and guidelines that would impact the amount of the actual rebates, the Company’s expectations regarding future rebates for these programs and estimated levels of inventory in the distribution channel.
	Patient Assistance
	The Company offers a co-pay card program to assist commercially insured patients with the cost of their HORIZANT related co-payments. Participating retail pharmacies get reimbursed by the Company for the amount of the co-pay assistance provided to eligible patients. The Company estimates and accrues the cost of the co-pay program based on historical redemption activity for this program. The Company reimburses the participating pharmacies approximately one month after the prescriptions subject to co-pay assistance are filled.
	Multiple-Element Arrangements
	Revenue arrangements are accounted for in accordance with the provisions of the Revenue Recognition-Multiple-Element Arrangements topic of the Codification.
	In evaluating arrangements with multiple elements, the Company considers whether components of the arrangement represent separate units of accounting based upon whether certain criteria are met, including whether the delivered element has stand-alone value to the customer and whether there is objective and reliable evidence of the fair value of the undelivered items. This evaluation requires subjective determinations and requires management to make judgments about the fair value of individual elements and whether such elements are separable from other aspects of the contractual relationship. The consideration received in such arrangements is allocated among the separate units of accounting based on the relative selling price method under which the selling price for each deliverable is determined using vendor-specific objective evidence of selling price, if it exists; otherwise, third-party evidence of selling price. If vendor-specific objective evidence and third-party evidence of selling price are not available for a deliverable, the Company will use its best estimate of the selling price for that deliverable when applying the relative selling price method. The applicable revenue recognition criteria are applied to each of the separate units.
	Revenues from multiple deliverables combined as a single unit of accounting are deferred and recognized over the period during which the Company remains obligated to perform services. The specific methodology for the recognition of the revenue (e.g., straight-line or according to specific performance criteria) is determined on a case-by-case basis according to the facts and circumstances applicable to a given agreement.
	Payments received in excess of revenues recognized are recorded as deferred revenue until such time as the revenue recognition criteria have been met.
	Collaboration revenue consisted of the recognition of revenues from upfront and milestone payments from the Company’s partnership with Astellas Pharma Inc. and from upfront and additional payments from its license agreement with Indivior. Net revenue from unconsolidated joint operating activities included all revenue that resulted solely from the Company’s terminated collaboration agreement with GSK. The Company accounts for the revenue-related activities of these collaboration agreements as follows:

		•		Up-front, licensing-type payments. Up-front, licensing-type payments are assessed to determine whether or not the licensee is able to obtain any stand-alone value from the license. Where this is not the case, the Company does not consider the license deliverable to be a separate unit of accounting, and the revenue is deferred with revenue recognition for the license fee being assessed in conjunction with the other deliverables that constitute the combined unit of accounting.

		•		Milestones. Revenue recognition will occur only if the consideration earned from the achievement of a milestone meets all the criteria for the milestone to be considered substantive at the inception of the arrangement, such that it: (i) is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the item delivered as a result of a specific outcome resulting from the Company’s performance to achieve the milestone; (ii) relates solely to past performance; and (iii) is reasonably relative to all deliverables and payment terms in the arrangement.
	The Company will assess the nature of contingent payments, and appropriate accounting for, these payments on a case-by-case basis in accordance with the provisions of the Revenue Recognition topic of the Codification.

		•		Profit and loss sharing. This represented the Company’s share of the profits and losses from the co-promotion of HORIZANT with GSK under the terminated collaboration with GSK. Amounts were recognized in the period in which the related activities occurred, and their financial statement classification was based on the Company’s assessment that these activities constituted part of the Company’s ongoing central operations.

		•		Product royalties. The Company is entitled to receive royalties on net sales of gabapentin enacarbil (known as REGNITE) in Japan. Astellas initiated sales of REGNITE in Japan in July 2012, and the Company recognizes the associated product royalties when they can be reliably measured and collectability is reasonably assured (generally upon receipt of the royalty payment).
Cost of Product Sales	Cost of Product Sales
Cost of Product Sales	Cost of product sales includes direct and indirect costs to manufacture product sold, including tableting, packaging, storage, shipping and handling costs and inventory write-downs, if any.
Accounts Receivable	Accounts Receivable
Accounts Receivable	Trade accounts receivable are recorded net of allowances for cash discounts for prompt payment, wholesaler discounts and chargebacks. The need for bad debt allowance is evaluated each reporting period based on the Company’s assessment of the credit worthiness of its customers.
Inventories	Inventories
	Inventories are stated at the lower of cost or market. Cost is determined on a first-in, first-out, or FIFO, basis. Inventories include active pharmaceutical ingredient, or API, and contract manufacturing costs. The Company regularly evaluates the Company’s inventories for excess quantities and obsolescence (expiration), taking into account such factors as historical and anticipated future sales compared to quantities on hand and the remaining shelf life of HORIZANT. Write-downs of inventories are considered to be permanent reductions in the cost basis of inventories.
	Inventories that are not expected to be consumed within 12 months following the balance sheet date are classified as long-term inventories.
	Inventories as of December 31, 2014 and 2013 were summarized as follows (in thousands):


			Year Ended December 31,
			2014			2013
	Raw materials		$	9,273		$	10,258
	Work in progress			517			76
	Finished goods			766			1,113

	Total inventory			10,556			11,447
	Less: Long-term inventories			9,098			10,185

	Total inventory classified as current		$	1,458		$	1,262


	Long-term inventories consisted of gabapentin enacarbil API used for production of HORIZANT. The Company evaluates demand for HORIZANT and expected consumption of the API based on long-term projected sales of HORIZANT.
Research and Development	Research and Development
Research and Development	All research and development costs, including those funded by third parties, are expensed as incurred. Research and development costs consisted of salaries, employee benefits, laboratory supplies, costs associated with clinical trials, including amounts paid to clinical research organizations, other professional services and facility costs.
Clinical Trials	Clinical Trials
Clinical Trials	The Company accrues and expenses the costs for clinical trial activities performed by third parties based upon estimates of the percentage of work completed over the life of the individual study in accordance with agreements established with contract research organizations and clinical trial sites. The Company determines the estimates through discussions with internal clinical personnel and external service providers as to progress or stage of completion of trials or services and the agreed upon fee to be paid for such services. Costs of setting up clinical trial sites for participation in the trials are expensed immediately as research and development expenses. Clinical trial site costs related to patient visits are accrued as patients’ progress through the trial and are reduced by any payments made to the clinical trial site. Non-refundable advance payments for research and development goods or services are recognized as expense as the related goods are delivered or the related services are provided in accordance with the provisions of the Research and Development Arrangements topic of the Codification.
Nonretirement Postemployment Benefits	Nonretirement Postemployment Benefits
	On May 31, 2012, the Company adopted the XenoPort Amended and Restated 2012 Severance Plan, or the 2012 Severance Plan, for the benefit of the Company’s non-executive employees. Under the terms of the 2012 Severance Plan, a non-executive employee terminated by the Company because of elimination of his or her position is eligible to receive continuation of medical insurance under COBRA and specified severance payments based on the employee’s level and years of service with the Company. The Company accounts for employee termination benefits in accordance with the provisions of the Compensation-Nonretirement Postemployment Benefits topic of the Codification and records employee termination liabilities once they are both probable and estimable for severance provided under the Company’s existing severance program.
	On June 14, 2013, the Company implemented a reduction in force that included the elimination of certain non-executive positions as the Company completed certain work projects on its AP development program. As a result, the Company recorded severance benefits charges of $703,000 in 2013, which were included in the “Research and development” line of the “Operating expenses” section of the Company’s statements of comprehensive loss. As of December 31, 2014 and 2013, there were no associated liability balances.
Stock-Based Compensation	Stock-Based Compensation
	The Compensation — Stock Compensation topic of the Codification establishes accounting for stock-based awards exchanged for employee services. In accordance with this topic, for stock options, awards and stock purchase rights under the Company’s employee stock purchase plan, or ESPP, stock-based compensation cost is measured at grant date, based on the fair value of the award, and is recognized as expense over the requisite employee service period.

	The effect of recording stock-based compensation under the Compensation — Stock Compensation topic was as follows:


			Year Ended December 31,
			2014			2013			2012
			(In thousands, except
			per share amounts)
	Stock-based compensation by type of award:
	Employee stock options and awards		$	8,531		$	10,083		$	11,956
	ESPP			510			461			325

	Total stock-based compensation		$	9,041		$	10,544		$	12,281

	Effect on basic and diluted net loss per share		$	(0.15	)	$	(0.22	)	$	(0.31	)

	The Company’s employee non-cash stock-based compensation was reported as follows:


			Year Ended December 31,
			2014			2013			2012
			(In thousands)
	Research and development		$	2,062		$	3,059		$	4,364
	Selling, general and administrative			6,979			7,485			7,917

			$	9,041		$	10,544		$	12,281

	Valuation Assumptions
	The Company estimates the fair value of all of its stock options and stock purchase rights on the date of grant using a Black-Scholes valuation model that requires the input of highly subjective assumptions, including the option’s expected life and the price volatility of the underlying stock. The Company derived the expected life assumptions using data obtained from similar entities, taking into consideration factors such as industry, stage of life cycle, size and financial leverage. The Company has determined that its historical volatility can be used to derive the expected stock price volatility assumption. The Company expenses the resulting charge using the straight-line attribution method over the vesting period. Restricted stock units are measured at the fair value of the Company’s common stock on the date of grant and expensed over the period of vesting using the straight-line attribution approach. The calculation of the Black-Scholes valuations used the following weighted-average assumptions:


			Year Ended December 31,
			2014			2013			2012
	Dividend yield			0	%		0	%		0	%
	Volatility for options			0.81			0.82			0.81
	Volatility for ESPP			0.55			0.59			0.65
	Weighted-average expected life of options (years)			5.25			5.25			5.09
	Weighted-average expected life of ESPP rights (years)			0.75			0.75			0.75
	Risk-free interest rate for options			1.52-1.77	%		0.70-1.60	%		0.62-1.02	%
	Risk-free interest rate for ESPP rights			0.05-0.17	%		0.07-0.17	%		0.07-0.27	%
Income Taxes	Income Taxes
	Income taxes are accounted for in accordance with the Income Taxes topic of the Codification using the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities as measured by the enacted tax rates that will be in effect when these differences reverse. The Company provides a valuation allowance against net deferred tax assets if, based upon the available evidence, it is more-likely-than-not that the deferred tax assets will not be realized.

	The recognition, derecognition and measurement of a tax position is based on management’s best judgment given the facts, circumstances and information available at the reporting date.
	As of December 31, 2014, the Company had unrecognized tax benefits and expects no significant changes in unrecognized tax benefits in the next 12 months (see Note 10 for more information).
	The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense. To date, there have been no interest or penalties charged to the Company in relation to the underpayment of income taxes.
Comprehensive Loss	Comprehensive Loss
Comprehensive Loss	The Company presents all non-owner changes in stockholders’ equity in a single continuous statement of comprehensive loss and shows: (i) each component of net loss along with total net loss; (ii) each component of other comprehensive loss along with a total for other comprehensive loss; and (iii) a total amount for comprehensive loss. The Company’s other comprehensive loss is comprised of unrealized gains (losses) on available-for-sale securities.
Advertising Costs	Advertising Costs
Advertising Costs	Advertising costs, included in selling, general and administrative expenses, are charged to expense as incurred. Advertising expenses for the year ended December 31, 2014 and 2013, was $9,568,000 and $8,244,000, respectively. The Company did not have advertising costs for the year ended December 31, 2012.
Net Loss Per Share	Net Loss Per Share
	Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period without consideration for potential common shares. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period plus any dilutive potential common shares for the period determined using the treasury-stock method. For purposes of this calculation, restricted stock units, options to purchase stock and warrants are considered to be potential common shares and are only included in the calculation of diluted net loss per share when their effect is dilutive.


			Year Ended December 31,
			2014			2013			2012
			(In thousands, except
			per share amounts)
	Numerator:
	Net loss		$	(49,333	)	$	(85,883	)	$	(30,814	)

	Denominator:
	Weighted-average common shares outstanding			60,856			47,545			39,434

	Basic and diluted net loss per share		$	(0.81	)	$	(1.81	)	$	(0.78	)

	Outstanding securities at period end not included in the computation of diluted net loss per share as they had an anti-dilutive effect:
	Restricted stock units and options to purchase common stock			7,650			6,824			6,339
	Warrants outstanding			—			283			283

				7,650			7,107			6,622

	On January 29, 2014, the Company completed an underwritten public offering of 12,000,000 shares of its common stock at a price to the public of $6.00 per share. On February 21, 2014, the underwriters exercised in full their option to purchase 1,800,000 additional shares.

	On February 3, 2015, the Company completed a private placement of $115,000,000 aggregate principal amount of 2.50% Convertible Senior Notes due 2022, or the 2022 Notes, to the investment bank acting as the initial purchaser who subsequently resold the 2022 Notes to qualified institutional buyers. The 2022 Notes are convertible at an initial conversion rate of 93.2945 shares of the Company’s common stock per $1,000 principal amount of the 2022 Notes, which is equal to an initial conversion price of approximately $10.72 per share of common stock (see Note 12 for more information).
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In May 2014, the FASB issued Accounting Standards Update, or ASU, No. 2014-09, Revenue from Contracts with Customers: Topic 606 (ASU 2014-09), which creates a single source of revenue guidance under GAAP for all companies in all industries. The core principle of ASU 2014-09 is that revenue should be recognized in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 defines a five-step process in order to achieve this core principle, which may require the use of judgment and estimates. ASU 2014-09 also requires expanded qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and estimates used. ASU 2014-09 will be effective for the Company in the first quarter of fiscal 2017, and early adoption is not permitted. The Company may adopt ASU 2014-09 either by way of a full retrospective approach for all periods presented in the period of adoption or a modified retrospective approach. The Company is currently evaluating the impact that ASU 2014-09 will have on its financial statements and has not yet determined which transition method it will apply.
	In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014-15). This update is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 requires management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. Specifically, the amendments: (1) provide a definition of the term substantial doubt; (2) require an evaluation every reporting period including interim periods; (3) provide principles for considering the mitigating effect of management’s plans; (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans; (5) require an express statement and other disclosures when substantial doubt is not alleviated; and (6) require an assessment for a period of one year after the date that the financial statements are issued (or available to be issued). ASU 2014-15 will be effective for annual periods ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016, with early adoption permitted. ASU 2014-15 will be effective for the Company beginning with its annual report for fiscal 2016 and interim periods thereafter. The Company is currently evaluating the impact that ASU 2014-15 will have on its financial statements.

Organization_and_Summary_of_Si2

Organization and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory	Inventories as of December 31, 2014 and 2013 were summarized as follows (in thousands):


		Year Ended December 31,
		2014			2013
	Raw materials	$	9,273		$	10,258
	Work in progress		517			76
	Finished goods		766			1,113

	Total inventory		10,556			11,447
	Less: Long-term inventories		9,098			10,185

	Total inventory classified as current	$	1,458		$	1,262

Stock-Based Compensation by Type of Award	The effect of recording stock-based compensation under the Compensation — Stock Compensation topic was as follows:


		Year Ended December 31,
		2014			2013			2012
		(In thousands, except
		per share amounts)
	Stock-based compensation by type of award:
	Employee stock options and awards	$	8,531		$	10,083		$	11,956
	ESPP		510			461			325

	Total stock-based compensation	$	9,041		$	10,544		$	12,281

	Effect on basic and diluted net loss per share	$	(0.15	)	$	(0.22	)	$	(0.31	)

Employee Non-Cash Stock-Based Compensation Excluding Non-Cash Stock-Based Compensation Resulting from Twenty Ten Restructuring Plan	The Company’s employee non-cash stock-based compensation was reported as follows:


		Year Ended December 31,
		2014			2013			2012
		(In thousands)
	Research and development	$	2,062		$	3,059		$	4,364
	Selling, general and administrative		6,979			7,485			7,917

		$	9,041		$	10,544		$	12,281

Black-Scholes Valuation Assumptions to Estimates Fair Value of Stock Options and Stock Purchase Rights	The calculation of the Black-Scholes valuations used the following weighted-average assumptions:


		Year Ended December 31,
		2014			2013			2012
	Dividend yield		0	%		0	%		0	%
	Volatility for options		0.81			0.82			0.81
	Volatility for ESPP		0.55			0.59			0.65
	Weighted-average expected life of options (years)		5.25			5.25			5.09
	Weighted-average expected life of ESPP rights (years)		0.75			0.75			0.75
	Risk-free interest rate for options		1.52-1.77	%		0.70-1.60	%		0.62-1.02	%
	Risk-free interest rate for ESPP rights		0.05-0.17	%		0.07-0.17	%		0.07-0.27	%
Net Loss Per Share
		Year Ended December 31,
		2014			2013			2012
		(In thousands, except
		per share amounts)
	Numerator:
	Net loss	$	(49,333	)	$	(85,883	)	$	(30,814	)

	Denominator:
	Weighted-average common shares outstanding		60,856			47,545			39,434

	Basic and diluted net loss per share	$	(0.81	)	$	(1.81	)	$	(0.78	)

	Outstanding securities at period end not included in the computation of diluted net loss per share as they had an anti-dilutive effect:
	Restricted stock units and options to purchase common stock		7,650			6,824			6,339
	Warrants outstanding		—			283			283

			7,650			7,107			6,622

License_and_Collaboration_Agre1

License and Collaboration Agreements (Tables)	12 Months Ended
License and Collaboration Agreements (Tables)	Dec. 31, 2014
Revenue from License Agreement	The following table presents the Company’s total revenues that have been recognized during the year indicated pursuant to its current license agreement with Astellas and Indivior and its terminated collaboration agreement with GSK (in thousands):


		Year Ended December 31,
		2014		2013		2012
	Astellas	$	1,695	$	1,537	$	11,624
	GSK		—		—		10,000
	Indivior		25,000		—		—

		$	26,695	$	1,537	$	21,624

Acquisitions_and_AcquisitionRe1

Acquisitions and Acquisition-Related Items (Tables)	12 Months Ended
Acquisitions and Acquisition-Related Items (Tables)	Dec. 31, 2014
Fair Value of Net Identified Assets Acquired and Consideration Exchanged	The following table summarizes the fair value of consideration exchanged as part of the termination and transition agreement (in thousands):


	Cash payable to GSK (recorded as “Other noncurrent liability” on the Company’s Balance Sheet for the year ended December 31, 2012)	$	2,314
	Issuance of common shares to GSK		30,268
	Cash received for common shares issued to GSK		(40,000	)
	Settlement of litigation with GSK		20,499
	Transaction costs		476

		$	13,557

Assets acquired (Detail)	Assets acquired as a result of this transaction were as follows (in thousands):


	Inventories	$	11,733
	Manufacturing property and equipment		1,967

	Total assets acquired	$	13,700

Proforma Consolidated Revenues and Net Loss	The following unaudited supplemental pro forma information summarizes the combined results of operations of the Company and the HORIZANT business as though the acquisition had occurred on January 1, 2012 (in thousands):


		Year Ended
		December 31,
		2013			2012
	Revenues	$	9,128		$	28,119
	Net loss	$	92,791		$	84,695

Cash_and_Cash_Equivalents_Shor1

Cash and Cash Equivalents, Short-Term Investments and Restricted Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Cash and Cash Equivalents, Short-Term Investments and Restricted Investments	The following are summaries of cash and cash equivalents, short-term investments and restricted investments (in thousands):


		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
	As of December 31, 2014:
	Cash	$	3,383	$	—	$	—		$	3,383
	Money market funds		8,576		—		—			8,576
	U.S. government-sponsored agencies		2,000		—		(2	)		1,998
	Corporate debt securities		88,127		12		(40	)		88,099
	Certificates of deposit		1,725		—		—			1,725

		$	103,811	$	12	$	(42	)	$	103,781

	Reported as:
	Cash and cash equivalents								$	11,958
	Short-term investments									90,098
	Restricted investments									1,725

									$	103,781

		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
	As of December 31, 2013:
	Cash	$	2,281	$	—	$	—		$	2,281
	Money market funds		10,046		—		—			10,046
	U.S. government-sponsored agencies		2,500		—		—			2,500
	Corporate debt securities		43,831		6		(6	)		43,831
	Certificates of deposit		1,725		—		—			1,725

		$	60,383	$	6	$	(6	)	$	60,383

	Reported as:
	Cash and cash equivalents								$	20,584
	Short-term investments									38,074
	Restricted investments									1,725

									$	60,383

Available-For-Sale Investments Measured at Fair Value
		Total As of		Fair Value Measurements at Reporting Date Using
		December 31,		Fair Value Measurements at Reporting Date Using
	Description	2014		Quoted Prices		Significant			Significant
				in Active		Other			Unobservable
				Markets		Observable			Inputs
				for Identical		Inputs			(Level 3)
				Assets		(Level 2)
				(Level 1)
	Money market funds	$	8,576	$	8,576	$	—		$	—
	U.S. government-sponsored agencies		1,998		—		1,998			—
	Corporate debt securities		88,099		—		88,099			—
	Certificates of deposit		1,725		—		1,725			—

	Total	$	100,398	$	8,576	$	91,822		$	—



		Total As of		Fair Value Measurements at Reporting Date Using
		December 31,		Fair Value Measurements at Reporting Date Using
	Description	2013		Quoted Prices		Significant			Significant
				in Active		Other			Unobservable
				Markets		Observable			Inputs
				for Identical		Inputs			(Level 3)
				Assets		(Level 2)
				(Level 1)
	Money market funds	$	10,046	$	10,046	$	—		$	—
	U.S. government-sponsored agencies		2,500		—		2,500			—
	Corporate debt securities		43,831		—		43,831			—
	Certificates of deposit		1,725		—		1,725			—

	Total	$	58,102	$	10,046	$	48,056		$	—

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Dec. 31, 2014
Property and Equipment	Property and equipment at December 31, 2014 and 2013 consisted of the following (in thousands):


		December 31,
		2014			2013
	Laboratory equipment	$	10,561		$	10,701
	Manufacturing property and equipment		1,975			1,967
	Furniture and fixtures		1,076			1,107
	Computer equipment and software		5,656			5,475
	Leasehold improvements		3,405			3,344

			22,673			22,594
	Less: Accumulated depreciation and amortization		(20,251	)		(20,042	)

	Property and equipment, net	$	2,422		$	2,552

Other_Accrued_Liabilities_Tabl

Other Accrued Liabilities (Tables)	12 Months Ended
Other Accrued Liabilities (Tables)	Dec. 31, 2014
Other Accrued Liabilities	Other accrued liabilities at December 31, 2014 and 2013 were as follows (in thousands):


		December 31,
		2014		2013
	Accrued product costs	$	2,009	$	1,903
	Accrued selling and marketing expenses		1,210		883
	Accrued general and administrative expenses		466		632
	Accrued rebates, allowances and returns		986		315
	Other liabilities		446		205

	Total other accrued liabilities	$	5,117	$	3,938

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2014
Future Minimum Payments under The Company's Non-Cancelable Operating Lease	At December 31, 2014, future minimum payments under the Company’s non-cancelable operating lease were as follows (in thousands):


	Year ending December 31:
	2015	$	2,368
	2016		986

	Total minimum lease payments	$	3,354

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
Stockholders' Equity (Tables)	Dec. 31, 2014
Option Activity	A summary of option activity as of and for the year ended December 31, 2014 is presented below:


		Shares			Weighted-		Weighted-		Aggregrate
					Average		Average		Intrinsic Value
					Exercise		Remaining
					Price		Contractual
							Term
									(In Thousands)
	Outstanding at January 1, 2014		5,368,964		$	16.81
	Options granted		1,986,620			6.12
	Options cancelled		(437,453	)		11.6
	Options exercised		(289,519	)		4.49

	Outstanding at December 31, 2014		6,628,612			14.49		5.86	$	(8,283	)

	Exercisable at December 31, 2014		4,504,585		$	18.26		4.45	$	(3,427	)

Restricted Stock Unit Activity	A summary of restricted stock unit activity for the year ended December 31, 2014 is presented below:


		Shares			Weighted-
					Average
					Grant Date
					Fair Value
	Outstanding at January 1, 2014		1,455,190		$	7.15
	Awards granted		394,790			6.07
	Awards cancelled		(188,500	)		6.87
	Awards vested		(640,136	)		7.27

	Outstanding at December 31, 2014		1,021,344		$	6.7

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2014
Significant Components of Net Deferred Tax Assets	Significant components of the Company’s net deferred tax assets were as follows (in thousands):



		December 31,
		2014			2013
	Net operating loss carryforwards	$	182,791		$	161,663
	Research credit carryforwards		31,249			30,111
	Capitalized research and development		3,760			5,579
	Deferred revenue		4,824			4,700
	Stock awards		16,901			14,672
	Other		3,043			1,605

	Total net deferred tax assets		242,568			218,330
	Valuation allowance		(242,568	)		(218,330	)

	Net deferred tax assets	$	—		$	—

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is as follows (in thousands):



	January 1, 2013	$	—
	Increases related to prior year tax positions		1,340

	December 31, 2013		1,340
	Increases related to currrent year tax positions		50

	December 31, 2014	$	1,390

Quarterly_Financial_Data_Unaud1

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
Quarterly Financial Data (Unaudited) (Tables)	Dec. 31, 2014
Quarterly Financial Data	The following table summarizes the unaudited quarterly financial data for the last two fiscal years (in thousands, except per share data):



			Quarter Ended
			Dec. 31,			Sept. 30,		June 30,			March 31,			Dec. 31,			Sept. 30,			June 30,			March 31,
			2014			2014(1)		2014			2014			2013			2013			2013			2013
	Selected Quarterly Data:
	Total revenues		$	7,091		$	31,068	$	5,334		$	3,375		$	2,879		$	2,527		$	2,086		$	459

	Gross profit(2)		$	6,143		$	5,088	$	4,321		$	2,527		$	2,121		$	1,732		$	1,391		$	—

	Net income (loss)		$	(17,657	)	$	8,259	$	(19,387	)	$	(20,548	)	$	(19,138	)	$	(18,816	)	$	(24,381	)	$	(23,548	)

	Basic and diluted net income (loss) per share		$	(0.28	)	$	0.13	$	(0.31	)	$	(0.36	)	$	(0.40	)	$	(0.39	)	$	(0.51	)	$	(0.50	)



	-1	Total revenues and net income was primarily from the recognition of $25,000,000 in collaboration revenue resulting from the Indivior licensing agreement (see Note 2 for more information).


	-2	Gross profit relates solely to HORIZANT product sales.

Organization_and_Summary_of_Si3

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 03, 2015	Jan. 29, 2014	Feb. 21, 2014	Dec. 31, 2006
	Segment	Dec. 31, 2013	Dec. 31, 2012	Feb. 03, 2015	Jan. 29, 2014	Feb. 21, 2014	Dec. 31, 2006
Organization And Summary Of Significant Accounting Policies [Line Items]
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 2	$1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 3	1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 4	1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 5	1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, after year 5	1,000,000
Long term commitment period	6 years
Long term commitment effective period	2016
Effective interest rate	17.50%
Restricted investments	1,500,000	1,500,000
Letter of credit pledged	225,000						1,500,000
Number of operating segment	1
Low risk debt securities, maturity period	16 months
Cash discount offers to customers	2.00%
Advertising expenses	9,568,000	8,244,000	0
Common stock price	$8.77
Underwriters exercised the full option to purchase additional shares						1,800,000
Computer Equipment
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	3 years
Deposits on Leased Facilities
Organization And Summary Of Significant Accounting Policies [Line Items]
Restricted investments	1,500,000	1,500,000
Certificates of deposit
Organization And Summary Of Significant Accounting Policies [Line Items]
Restricted investments	225,000	225,000
Sales Revenue, Net
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of wholesale distributors	3	3
Accounts Receivable
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of customers	3	3
Nonretirement Postemployment Benefits
Organization And Summary Of Significant Accounting Policies [Line Items]
Severance benefits charges		703,000
Customer Concentration Risk [Member] \| Sales Revenue, Net \| Wholesale Distributor One
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	41.00%	47.00%
Customer Concentration Risk [Member] \| Sales Revenue, Net \| Wholesale Distributor Two
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	28.00%	33.00%
Customer Concentration Risk [Member] \| Sales Revenue, Net \| Wholesale Distributor Three
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	26.00%	16.00%
Customer Concentration Risk [Member] \| Accounts Receivable \| Wholesale Distributor One
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	48.00%	45.00%
Customer Concentration Risk [Member] \| Accounts Receivable \| Wholesale Distributor Two
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	26.00%	29.00%
Customer Concentration Risk [Member] \| Accounts Receivable \| Wholesale Distributor Three
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	22.00%	22.00%
Subsequent Event
Organization And Summary Of Significant Accounting Policies [Line Items]
Convertible senior notes, principal offer amount				115,000,000
Convertible senior notes, stated interest rate				2.50%
Convertible senior notes, due date				2022
Convertible senior notes, conversion share per 1000 principal amount				93.2945
Convertible senior notes, conversion rate of 93.2945 per principal amount				$1,000
Convertible senior notes, initial conversion price				$10.72
Underwritten Public Offering
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock issued in underwritten public offering					12,000,000
Common stock price					$6
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Maturity period of highly liquid investments classified as cash equivalents	90 days
Maximum \| Furniture, Fixtures and Equipment
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	10 years
Minimum \| Furniture, Fixtures and Equipment
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives	5 years

Inventory_Detail

Inventory (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$9,273	$10,258
Work in progress	517	76
Finished goods	766	1,113
Total inventory	10,556	11,447
Less: Long-term inventories	9,098	10,185
Total inventory classified as current	$1,458	$1,262

StockBased_Compensation_by_Typ

Stock-Based Compensation by Type of Award (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$9,041	$10,544	$12,281
Effect on basic and diluted net loss per share	($0.15)	($0.22)	($0.31)
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	8,531	10,083	11,956
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$510	$461	$325

Employee_NonCash_StockBased_Co

Employee Non-Cash Stock-Based Compensation (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Non-cash stock-based compensation	$9,041	$10,544	$12,281
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Non-cash stock-based compensation	2,062	3,059	4,364
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Non-cash stock-based compensation	$6,979	$7,485	$7,917

BlackScholes_Valuation_Assumpt

Black-Scholes Valuation Assumptions to Estimates Fair Value of Stock Options and Stock Purchase Rights (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility rate	0.81%	0.82%	0.81%
Weighted-average expected life	5 years 3 months	5 years 3 months	5 years 1 month 2 days
Risk-free interest rate, minimum	1.52%	0.70%	0.62%
Risk-free interest rate, maximum	1.77%	1.60%	1.02%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility rate	0.55%	0.59%	0.65%
Weighted-average expected life	9 months	9 months	9 months
Risk-free interest rate, minimum	0.05%	0.07%	0.07%
Risk-free interest rate, maximum	0.17%	0.17%	0.27%

Net_Loss_Per_Share_Detail

Net Loss Per Share (Detail) (USD $)	3 Months Ended									12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Numerator:
Net loss	($17,657)	$8,259	[1]	($19,387)	($20,548)	($19,138)	($18,816)	($24,381)	($23,548)	($49,333)	($85,883)	($30,814)
Denominator:
Weighted-average common shares outstanding										60,856	47,545	39,434
Basic and diluted net loss per share	($0.28)	$0.13	[1]	($0.31)	($0.36)	($0.40)	($0.39)	($0.51)	($0.50)	($0.81)	($1.81)	($0.78)
Outstanding securities at period end not included in the computation of diluted net loss per share as they had an anti-dilutive effect:
Outstanding securities not included in the computation of diluted net loss per share										7,650	7,107	6,622
Restricted stock units and options to purchase common stock
Outstanding securities at period end not included in the computation of diluted net loss per share as they had an anti-dilutive effect:
Outstanding securities not included in the computation of diluted net loss per share										7,650	6,824	6,339
Warrants outstanding
Outstanding securities at period end not included in the computation of diluted net loss per share as they had an anti-dilutive effect:
Outstanding securities not included in the computation of diluted net loss per share											283	283

[1]	Total revenues and net income was primarily from the recognition of $25,000,000 in collaboration revenue resulting from the Indivior licensing agreement (see Note 2 for more information).

License_and_Collaboration_Arra

License and Collaboration Arrangements - Additional Information (Detail) (USD $)

3 Months Ended

12 Months Ended

70 Months Ended

1 Months Ended

64 Months Ended

1 Months Ended

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Mar. 31, 2007

Jun. 30, 2012

Jun. 30, 2014

Jul. 31, 2014

31-May-14

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Collaboration revenue

$26,134,000

$1,137,000

$11,515,000

Revenue recognized

7,091,000

31,068,000

[1]

5,334,000

3,375,000

2,879,000

2,527,000

2,086,000

459,000

46,868,000

7,951,000

21,624,000

Royalty revenue

561,000

400,000

109,000

Deferred revenue, current

1,134,000

Deferred revenue, non-current

10,864,000

11,997,000

10,864,000

11,997,000

Net revenue from unconsolidated joint operating activities

10,000,000

Indivior PLC

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Collaboration revenue

25,000,000

Glaxo Group Limited

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Net revenue from unconsolidated joint operating activities

10,000,000

Glaxo Group Limited | Exclusive collaboration to develop and commercialize gabapentin enacarbil

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Revenue recognized

205,000,000

Glaxo Group Limited | Exclusive collaboration to develop and commercialize gabapentin enacarbil | Upon the occurrence of additional clinical and regulatory events

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Payments, maximum amount

130,000,000

Glaxo Group Limited | Exclusive collaboration to develop and commercialize gabapentin enacarbil | Upfront, non-refundable cash payment

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Deferred revenue, initial up-front license payment and payment for specified materials received

75,000,000

Glaxo Group Limited | Exclusive collaboration to develop and commercialize gabapentin enacarbil | In connection with the first commercial sale of Horizan

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Revenue recognized

10,000,000

Glaxo Group Limited | Exclusive collaboration to develop and commercialize gabapentin enacarbil | Clinical Trials and Pre-clinical Activities

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Revenue recognized

85,000,000

Licensing Agreements | Indivior PLC

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Collaboration revenue

25,000,000

Licensing Agreements | Indivior PLC | Upfront, non-refundable cash payment

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Deferred revenue, initial up-front license payment and payment for specified materials received

20,000,000

Collaboration revenue

20,000,000

Licensing Agreements | Indivior PLC | Additional payment for specified materials

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Deferred revenue, initial up-front license payment and payment for specified materials received

5,000,000

Collaboration revenue

5,000,000

Licensing Agreements | Indivior PLC | Achievement of certain predefined milestones

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Payments, maximum amount

120,000,000

Licensing Agreements | Indivior PLC | Regulatory and development-based milestones

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Payments, maximum amount

70,000,000

Licensing Agreements | Indivior PLC | Commercialization-based milestones

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Payments, maximum amount

50,000,000

Licensing Agreements | Astellas Pharma Inc.

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Revenue recognized

54,073,000

Royalty revenue

561,000

400,000

109,000

Deferred revenue

11,998,000

Deferred revenue, current

1,134,000

Deferred revenue, non-current

10,864,000

Licensing Agreements | Astellas Pharma Inc. | Approval of Regnite in Japan

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Revenue recognized

10,000,000

Licensing Agreements | Astellas Pharma Inc. | Upfront, non-refundable cash payment

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Collaboration revenue

$1,134,000

$1,137,000

$1,515,000

[1]

Total revenues and net income was primarily from the recognition of $25,000,000 in collaboration revenue resulting from the Indivior licensing agreement (see Note 2 for more information).

Total_Revenues_Recognized_Purs

Total Revenues Recognized Pursuant to Current License Agreements (Detail) (USD $)	3 Months Ended									12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net revenue from unconsolidated joint operating activities												$10,000,000
Collaboration revenue										26,134,000	1,137,000	11,515,000
Total revenues	7,091,000	31,068,000	[1]	5,334,000	3,375,000	2,879,000	2,527,000	2,086,000	459,000	46,868,000	7,951,000	21,624,000
Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenues										26,695,000	1,537,000	21,624,000
Astellas Pharma Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and royalty revenue										1,695,000	1,537,000	11,624,000
Glaxo Group Limited
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net revenue from unconsolidated joint operating activities										0	0	10,000,000
Indivior PLC
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue										$25,000,000

[1]	Total revenues and net income was primarily from the recognition of $25,000,000 in collaboration revenue resulting from the Indivior licensing agreement (see Note 2 for more information).

Acquisition_and_Acquisition_Re

Acquisition and Acquisition Related items - Additional Information (Detail) (USD $)	0 Months Ended		1 Months Ended	12 Months Ended
	Nov. 09, 2012	Nov. 08, 2012	Oct. 31, 2012	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2013
Business Acquisition [Line Items]
Proceed from issuance of common stock		$40,000,000			$30,268,000
Percentage of stock issue price over average stock closing price	12.50%	12.50%
Common Stock Trading Days to be Considered For Valuation	10 days		10 days
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 2				1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 3				1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 4				1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, Year 5				1,000,000
Payment for inventory of gabapentin enacarbil in GSK's possession, after year 5				1,000,000
Long term commitment period				6 years
Long term commitment effective period				2016
Horizant Business
Business Acquisition [Line Items]
Transaction costs						476,000
Glaxo Group Limited
Business Acquisition [Line Items]
Proceed from issuance of common stock	20,000,000	$20,000,000
Stock issued, shares	2,190,100	1,841,112
Stock issued, price per-shares	9.132	$10.86

Fair_Value_of_Net_Identifiable

Fair Value of Net Identifiable Assets Acquired and Consideration Exchanged (Detail) (USD $)	0 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Nov. 08, 2012	Dec. 31, 2012	Nov. 08, 2012
Business Acquisition [Line Items]
Cash payable to GSK (recorded as "Other noncurrent liability" on the Company's balance sheet for the year ended December 31, 2012)	$2,314
Issuance of common shares to GSK			30,268
Cash received for common shares issued to GSK	-40,000	-30,268
Settlement of litigation with GSK	20,499
Transaction costs			476
Consideration transferred , total	$13,557

Assets_Acquired_Detail

Assets Acquired (Detail) (USD $)	Dec. 31, 2013	1-May-13
In Thousands, unless otherwise specified	Dec. 31, 2013	1-May-13
Business Acquisition [Line Items]
Inventories	$11,733
Manufacturing property and equipment	1,967
Horizant Business
Business Acquisition [Line Items]
Inventories		11,733
Manufacturing property and equipment		1,967
Total assets acquired		$13,700

Proforma_Consolidated_Revenue_

Proforma Consolidated Revenue and Net Loss (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Revenues	$9,128	$28,119
Net loss	$92,791	$84,695

Cash_and_Cash_Equivalents_Shor2

Cash and Cash Equivalents, Short-Term Investments and Restricted Investments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Cost	$103,811	$60,383
Gross Unrealized Gains	12	6
Gross Unrealized Losses	-42	-6
Estimated Fair Value	103,781	60,383
Cash
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Available for Sale Securities Cost	3,383	2,281
Available-for-sale investments	3,383	2,281
Money market funds
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Available for Sale Securities Cost	8,576	10,046
Available-for-sale investments	8,576	10,046
U.S. government-sponsored agencies
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Available for Sale Securities Cost	2,000	2,500
Gross Unrealized Losses	-2
Available-for-sale investments	1,998	2,500
Corporate debt securities
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Available for Sale Securities Cost	88,127	43,831
Gross Unrealized Gains	12	6
Gross Unrealized Losses	-40	-6
Available-for-sale investments	88,099	43,831
Certificates of deposit
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Restricted Cost	1,725	1,725
Restricted Fair Value	1,725	1,725
Cash and cash equivalents
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Available-for-sale investments	11,958	20,584
Short-term investments
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Available-for-sale investments	90,098	38,074
Restricted investments
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Restricted Fair Value	$1,725	$1,725

Cash_and_Cash_Equivalents_Shor3

Cash and Cash Equivalents, Short-Term Investments and Restricted Investments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Gross realized gains or losses recognized	$0	$0	$0
Amounts reclassified out of accumulated other comprehensive loss to earnings	$0	$0	$0
Maximum
Cash Cash Equivalents Short Term Investments and Restricted Investments [Line Items]
Contractual maturities of investments held	16 months	1 year

AvailableForSale_Investments_M

Available-For-Sale Investments Measured at Fair Value (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$103,781	$60,383
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	8,576	10,046
U.S. government-sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	1,998	2,500
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	88,099	43,831
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Fair Value	1,725	1,725
Fair Value Measurements, Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	100,398	58,102
Fair Value Measurements, Recurring basis \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	8,576	10,046
Fair Value Measurements, Recurring basis \| U.S. government-sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	1,998	2,500
Fair Value Measurements, Recurring basis \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	88,099	43,831
Fair Value Measurements, Recurring basis \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Fair Value	1,725	1,725
Fair Value Measurements, Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	8,576	10,046
Fair Value Measurements, Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	8,576	10,046
Fair Value Measurements, Recurring basis \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	91,822	48,056
Fair Value Measurements, Recurring basis \| Significant Other Observable Inputs (Level 2) \| U.S. government-sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	1,998	2,500
Fair Value Measurements, Recurring basis \| Significant Other Observable Inputs (Level 2) \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	88,099	43,831
Fair Value Measurements, Recurring basis \| Significant Other Observable Inputs (Level 2) \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted Fair Value	$1,725	$1,725

Property_and_Equipment_Detail

Property and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Laboratory equipment	$10,561	$10,701
Manufacturing property and equipment	1,975	1,967
Furniture and fixtures	1,076	1,107
Computer equipment and software	5,656	5,475
Leasehold improvements	3,405	3,344
Property, Plant and Equipment, Gross, Total	22,673	22,594
Less: Accumulated depreciation and amortization	-20,251	-20,042
Property and equipment, net	$2,422	$2,552

Other_Accrued_Liabilities_Deta

Other Accrued Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Payables And Accruals [Abstract]
Accrued product costs	$2,009	$1,903
Accrued selling and marketing expenses	1,210	883
Accrued general and administrative expenses	466	632
Accrued rebates, allowances and returns	986	315
Other liabilities	446	205
Total other accrued liabilities	$5,117	$3,938

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended
	Nov. 30, 2014	Oct. 31, 2012	Feb. 29, 2008	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2006
Commitments and Contingencies Disclosure [Line Items]
Extended lease term	9 months	2 years
Lease commencement date			2001-12
Letter of credit pledged				$225,000			$1,500,000
Restricted investments				1,500,000	1,500,000
Rent expense				2,615,000	2,626,000	3,185,000
Net deferred rent asset				180,000	477,000
Deferred rent asset, current				127,000	308,000
Deferred rent asset, noncurrent				$53,000	$169,000
Second Amendment
Commitments and Contingencies Disclosure [Line Items]
Lease expiration date		27-Aug-15
Third Amendment [Member]
Commitments and Contingencies Disclosure [Line Items]
Lease expiration date	31-May-16
3400 Central Expressway, Santa Clara, California
Commitments and Contingencies Disclosure [Line Items]
Operating lease, area of office space			59,000
Operating lease, lease expiration year			2013-08
Operating lease, lease term			60 months
3410 Central Expressway, Santa Clara, California \| First Amendment
Commitments and Contingencies Disclosure [Line Items]
Operating lease, lease expiration year			2013-08
Extended lease term			2 years

Future_Minimum_Payments_under_

Future Minimum Payments under The Company's Non-Cancelable Operating Lease (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified	Dec. 31, 2014
Schedule of Operating Leases [Line Items]
2015	$2,368
2016	986
Total minimum lease payments	$3,354

Stockholders_Equity_Additional

Stockholders Equity - Additional Information (Detail) (USD $)

0 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

25 Months Ended

1 Months Ended

12 Months Ended

Dec. 16, 2005

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Jan. 29, 2014

Feb. 21, 2014

Jan. 31, 2005

Jan. 31, 2007

31-May-10

Dec. 31, 2010

Feb. 28, 2014

Jun. 10, 2014

31-May-08

Dec. 31, 2011

Jun. 30, 2014

Jun. 11, 2014

Stockholders Equity Note [Line Items]

Common stock, shares authorized

100,000,000

Closing stock price

$8.77

Stockholders' rights plan, expiration date

13-Jan-16

Equity Incentive Plans, weighted average exercise price

$6.12

Stock-based compensation expense

$9,041,000

$10,544,000

$12,281,000

Equity Incentive Plans, granted

1,986,620

Equity Incentive Plans, weighted-average grant date fair values of options granted

$4.05

$5.22

$3.12

Equity Incentive Plans, total intrinsic value of options exercised

758,000

304,000

137,000

Total fair value of options vested

4,572,000

4,786,000

8,107,000

Equity Incentive Plans, unvested options

2,124,027

Equity Incentive Plans, unvested awards

1,021,344

Equity Incentive Plans, total compensation cost not yet recognized

11,616,000

Equity Incentive Plans, estimated weighted-average amortization period

2 years 4 months 28 days

Equity Incentive Plans, granted

227,720

142,455

185,249

Warrants outstanding

283,420

Warrants exercise price

$25.40

Underwritten Public Offering

Stockholders Equity Note [Line Items]

Common stock issued in underwritten public offering

12,000,000

Closing stock price

Net cash proceeds from shares offering

67,300,000

Underwriters Over Allotment Option Exercised In Full

Stockholders Equity Note [Line Items]

Common stock issued in underwritten public offering

1,800,000

Net cash proceeds from shares offering

10,100,000

Restricted Stock Units (RSUs)

Stockholders Equity Note [Line Items]

Equity Incentive Plans, granted

394,790

Equity Incentive Plans, cancelled

188,500

Equity Incentive Plans, weighted-average grant date fair values

$6.07

$8.13

$5.22

Equity Incentive Plans, total fair value of restricted stock units vested

4,656,700

6,202,000

4,372,000

Equity Incentive Plans, unvested awards

1,021,344

1,455,190

Employee Stock Purchase Plan

Stockholders Equity Note [Line Items]

Stock-based compensation expense

510,000

461,000

325,000

Equity Incentive Plans, shares available for future grant

277,882

255,602

Employee Stock Option

Stockholders Equity Note [Line Items]

Stock-based compensation expense

8,531,000

10,083,000

11,956,000

Minimum

Stockholders Equity Note [Line Items]

Acquisition percentage of common stock to triggers exercise of preferred stock rights

15.00%

Tender offer percentage of common stock to trigger exercise of preferred stock right

15.00%

Maximum | Employee Stock Purchase Plan

Stockholders Equity Note [Line Items]

Equity Incentive Plans, exercise prices as a percentage of fair value of common stock

85.00%

Equity Incentive Plans, shares authorized for issuance

1,445,555

Equity Incentive Plans, annual increase in shares issuable as a percentage of common shares outstanding

1.00%

Equity Incentive Plans, annual increase in number of shares issuable

250,000

Stockholder Rights Plan | Series A Junior Participating Preferred Stock

Stockholders Equity Note [Line Items]

Equity Incentive Plans, weighted average exercise price

140

Stock Incentive Plan 1999

Stockholders Equity Note [Line Items]

Equity Incentive Plans, exercise prices as a percentage of fair value of common stock

85.00%

Equity Incentive Plans, vesting percentage

25.00%

Stock Incentive Plan 1999 | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

4 years

Stock Incentive Plan 1999 | Minimum

Stockholders Equity Note [Line Items]

Equity Incentive Plans, exercise prices as a percentage of fair value of common stock

100.00%

Stock Incentive Plan 1999 | Maximum

Stockholders Equity Note [Line Items]

Equity Incentive Plans, option expiration period

10 years

2005 Stock Incentive Plan

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

25.00%

2005 Stock Incentive Plan | Restricted Stock Units (RSUs) | Vesting Scenario One

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

25.00%

Equity Incentive Plans, vesting period

4 years

2005 Stock Incentive Plan | Restricted Stock Units (RSUs) | Vesting Scenario Two

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

3 years

Equity Incentive Plans, vesting percentage in year one

25.00%

Equity Incentive Plans, annual vesting percentage in year two

25.00%

Equity Incentive Plans, annual vesting percentage in year three

50.00%

2005 Stock Incentive Plan | Restricted Stock Units (RSUs) | Vesting Scenario Three

Stockholders Equity Note [Line Items]

Equity Incentive Plans, annual vesting percentage in year two

50.00%

Equity Incentive Plans, annual vesting percentage in year three

50.00%

2005 Stock Incentive Plan | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

4 years

2005 Stock Incentive Plan | Performance Stock Units

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

3 years

Equity Incentive Plans, granted

140,000

Equity Incentive Plans, granted date fair value

2,675,000

Equity Incentive Plans, cancelled

97,300

40,000

Equity Incentive Plans, outstanding

Stock-based compensation expense

232,000

638,000

2005 Stock Incentive Plan | Stock purchase rights, stock bonus rights, stock appreciation rights

Stockholders Equity Note [Line Items]

Equity Incentive Plans, shares authorized for issuance

2,000,000

Equity Incentive Plans, additional shares authorized for issuance

1,195,009

Equity Incentive Plans, shares available for future grant

2005 Stock Incentive Plan | Performance Stock Options

Stockholders Equity Note [Line Items]

Equity Incentive Plans, granted

316,000

Equity Incentive Plans, granted date fair value

1,334,000

Stock-based compensation expense

$445,000

2005 Stock Incentive Plan | Performance Stock Options | Upon Achievement of Performance Condition

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

50.00%

2005 Stock Incentive Plan | Performance Stock Options | Vest up on One-Year Anniversary Date of Initial Vest Date

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

50.00%

2005 Stock Incentive Plan | Minimum | Performance Stock Units

Stockholders Equity Note [Line Items]

Equity Incentive Plans, common stock subject to issuance

0.00%

2005 Stock Incentive Plan | Maximum

Stockholders Equity Note [Line Items]

Equity Incentive Plans, option expiration period

10 years

2005 Stock Incentive Plan | Maximum | Performance Stock Units

Stockholders Equity Note [Line Items]

Equity Incentive Plans, common stock subject to issuance

200.00%

2005 Stock Incentive Plan | Maximum | Stock purchase rights, stock bonus rights, stock appreciation rights

Stockholders Equity Note [Line Items]

Equity Incentive Plans, annual increase in shares issuable as a percentage of common shares outstanding

2.50%

Equity Incentive Plans, annual increase in number of shares issuable

2,000,000

2005 Non-Employee Directors Stock Option Plan | Restricted Stock Units (RSUs) | On Date Of Annual Meeting Of Shareholders

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

1 year

Equity Incentive Plans, granted

5,000

2005 Non-Employee Directors Stock Option Plan | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, additional shares authorized for issuance

120,000

Equity Incentive Plans, shares available for future grant

2005 Non-Employee Directors Stock Option Plan | Employee Stock Option | Initial Grant

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

4 years

24 months

Equity Incentive Plans, granted

25,000

30,000

2005 Non-Employee Directors Stock Option Plan | Employee Stock Option | On Date Of Annual Meeting Of Shareholders

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

12 months

Equity Incentive Plans, granted

10,000

15,000

2005 Non-Employee Directors Stock Option Plan | Maximum | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, option expiration period

10 years

Equity Incentive Plans, shares authorized for issuance

150,000

New Employee Inducement Stock Awards | Restricted Stock Units (RSUs)

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

4 years

Equity Incentive Plans, granted

10,000

New Employee Inducement Stock Awards | Nonqualified Stock Options

Stockholders Equity Note [Line Items]

Equity Incentive Plans, weighted average exercise price

42.59

Equity Incentive Plans, vesting period

4 years

Equity Incentive Plans, option expiration period

10 years

Equity Incentive Plans, granted

140,612

Equity Incentive Plans, vesting percentage on first anniversary

25.00%

Equity Incentive Plans, monthly vesting rate

Jan-48

2010 Inducement Plan | Restricted Stock Units (RSUs)

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

25.00%

Equity Incentive Plans, vesting period

4 years

2010 Inducement Plan | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

25.00%

Equity Incentive Plans, shares authorized for issuance

350,000

Equity Incentive Plans, additional shares authorized for issuance

625,000

Equity Incentive Plans, shares available for future grant

2010 Inducement Plan | Maximum | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, option expiration period

10 years

Equity Incentive Plans, shares authorized for issuance

975,000

2014 Equity Incentive Plan

Stockholders Equity Note [Line Items]

Equity Incentive Plans, shares available for future grant

4,479,789

4,471,059

2014 Equity Incentive Plan | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

25.00%

Equity Incentive Plans, vesting period

3 years

Equity Incentive Plans, option expiration period

10 years

2014 Equity Incentive Plan | Employee Stock Option | Initial Grant

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

24 months

Equity Incentive Plans, granted

30,000

2014 Equity Incentive Plan | Employee Stock Option | On Date Of Annual Meeting Of Shareholders

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

12 months

Equity Incentive Plans, granted

15,000

2014 Equity Incentive Plan | Restricted Stock

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting percentage

25.00%

Equity Incentive Plans, vesting period

4 years

2014 Equity Incentive Plan | Restricted Stock | On Date Of Annual Meeting Of Shareholders

Stockholders Equity Note [Line Items]

Equity Incentive Plans, vesting period

1 year

Equity Incentive Plans, granted

5,000

2014 Equity Incentive Plan | Maximum

Stockholders Equity Note [Line Items]

Equity Incentive Plans, additional shares authorized for issuance

7,847,852

2014 Equity Incentive Plan | Maximum | Employee Stock Option

Stockholders Equity Note [Line Items]

Equity Incentive Plans, option expiration period

10 years

Option_Activity_Detail

Option Activity (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014
Shares
Outstanding at January 1, 2014	5,368,964
Options granted	1,986,620
Options cancelled	-437,453
Options exercised	-289,519
Outstanding at December 31, 2014	6,628,612
Exercisable at December 31, 2014	4,504,585
Weighted-Average Exercise Price
Outstanding at January 1, 2014	$16.81
Options granted	$6.12
Options cancelled	$11.60
Options exercised	$4.49
Outstanding at December 31, 2014	$14.49
Exercisable at December 31, 2014	$18.26
Weighted-Average Remaining Contractual Term
Outstanding at December 31, 2014	5 years 10 months 10 days
Exercisable at December 31, 2014	4 years 5 months 12 days
Aggregate Intrinsic Value
Outstanding at December 31, 2014	($8,283)
Exercisable at December 31, 2014	($3,427)

Restricted_Stock_Unit_Activity

Restricted Stock Unit Activity (Detail) (USD $)	12 Months Ended
Restricted Stock Unit Activity (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Shares
Outstanding at December 31, 2014	1,021,344
Restricted Stock Units (RSUs)
Shares
Outstanding at January 1, 2014	1,455,190
Awards granted	394,790
Awards cancelled	-188,500
Awards vested	-640,136
Outstanding at December 31, 2014	1,021,344	1,455,190
Weighted-Average Grant Date Fair Value
Outstanding at January 1, 2014	$7.15
Awards granted	$6.07	$8.13	$5.22
Awards cancelled	$6.87
Awards vested	$7.27
Outstanding at December 31, 2014	$6.70	$7.15

Preferred_Stock_Additional_Inf

Preferred Stock - Additional Information (Detail)	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Preferred stock, shares authorized	5,000,000	5,000,000
Series A Junior Participating Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized	1,000,000	1,000,000

Significant_Components_of_Net_

Significant Components of Net Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Deferred Tax Assets and Liabilities [Line Items]
Net operating loss carryforwards	$182,791	$161,663
Research credit carryforwards	31,249	30,111
Capitalized research and development	3,760	5,579
Deferred revenue	4,824	4,700
Stock awards	16,901	14,672
Other	3,043	1,605
Total net deferred tax assets	242,568	218,330
Valuation allowance	-242,568	-218,330
Net deferred tax assets	$0	$0

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Line Items]
Increase in valuation allowance	$24,238,000	$27,210,000	$6,259,000
Valuation allowance	242,568,000	218,330,000
Valuation allowance related to stock option
Income Tax Disclosure [Line Items]
Valuation allowance	529,000
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	463,798,000
Research and development tax credit	24,022,000
Federal \| Expiration Beginning Year
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2022
Research and development tax credit, expiration year	2021
Federal \| Expiration Ending Year
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2034
Research and development tax credit, expiration year	2034
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	367,492,000
Research and development tax credit	$12,507,000
State \| Expiration Beginning Year
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2015
State \| Expiration Ending Year
Income Tax Disclosure [Line Items]
Net operating loss carryforwards, expiration year	2034

Reconciliation_of_Beginning_an

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Contingency [Line Items]
Beginning balance	$1,340
Increases related to current year tax positions	50
Increases related to prior year tax positions		1,340
Ending balance	$1,390	$1,340

Quarterly_Financial_Data_Detai

Quarterly Financial Data (Detail) (USD $)	3 Months Ended															12 Months Ended
Quarterly Financial Data (Detail) (USD $)	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information [Line Items]
Total revenues	$7,091,000		$31,068,000	[1]	$5,334,000		$3,375,000		$2,879,000		$2,527,000		$2,086,000		$459,000	$46,868,000	$7,951,000	$21,624,000
Gross profit	6,143,000	[2]	5,088,000	[1],[2]	4,321,000	[2]	2,527,000	[2]	2,121,000	[2]	1,732,000	[2]	1,391,000	[2]
Net income (loss)	-17,657,000		8,259,000	[1]	-19,387,000		-20,548,000		-19,138,000		-18,816,000		-24,381,000		-23,548,000	-49,333,000	-85,883,000	-30,814,000
Basic and diluted net income (loss) per share	($0.28)		$0.13	[1]	($0.31)		($0.36)		($0.40)		($0.39)		($0.51)		($0.50)	($0.81)	($1.81)	($0.78)
Collaboration revenue																26,134,000	1,137,000	11,515,000
Indivior PLC
Quarterly Financial Information [Line Items]
Collaboration revenue																25,000,000
Licensing Agreements \| Indivior PLC
Quarterly Financial Information [Line Items]
Collaboration revenue			$25,000,000

[1]	Total revenues and net income was primarily from the recognition of $25,000,000 in collaboration revenue resulting from the Indivior licensing agreement (see Note 2 for more information).
[2]	Gross profit relates solely to HORIZANT product sales.

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Subsequent Event, USD $)	0 Months Ended
	Feb. 03, 2015	Jan. 29, 2015
Subsequent Event [Line Items]
Convertible senior notes, principal offer amount	$115,000,000
Convertible senior notes, due date	2022
Convertible senior notes, conversion share per 1000 principal amount	93.2945
Convertible senior notes, conversion rate of 93.2945 per principal amount	$1,000
Convertible senior notes, repayment terms	Interest on the 2022 Notes will be payable semi-annually in cash in arrears on February 1 and August 1 of each year, beginning on August 1, 2015, at a rate of 2.50% per year.
Convertible senior notes, interest payment commencement date	1-Aug-15
Convertible senior notes, stated interest rate	2.50%
Convertible senior notes, repurchase price as a percentage of principal amount upon fundamental change by the company prior to debt maturity	100.00%
Minimum
Subsequent Event [Line Items]
Percentage of common stock shares from convertible debt		14.99%