Orexigen Therapeutics (OREX) 10-Q 9 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	5-May-14
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'OREX	'
Entity Registrant Name	'Orexigen Therapeutics, Inc.	'
Entity Central Index Key	'0001382911	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	116,327,411

Balance_Sheets

Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$37,563	$98,121
Investment securities, available-for-sale	117,528	78,875
Prepaid expenses and other current assets	1,289	1,286
Total current assets	156,380	178,282
Property and equipment, net	650	630
Other long-term assets	903	1,032
Restricted cash	177	177
Total assets	158,110	180,121
Current liabilities:	'	'
Accounts payable	5,442	4,787
Accrued clinical trial expenses	7,673	7,886
Accrued expenses	5,120	6,751
Deferred revenue, current portion	3,429	3,429
Total current liabilities	21,664	22,853
Long-term convertible debt	80,973	80,031
Deferred revenue, less current portion	34,286	35,143
Other long-term liabilities	337	232
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred stock, $.001 par value, 10,000,000 shares authorized at March 31, 2014 and December 31, 2013; no shares issued and outstanding at March 31, 2014 and December 31, 2013	'	'
Common stock, $.001 par value, 300,000,000 shares authorized at March 31, 2014 and December 31, 2013; 111,611,964 and 104,970,200 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	112	105
Additional paid-in capital	560,105	556,235
Accumulated other comprehensive income (loss)	6	-3
Accumulated deficit	-539,373	-514,475
Total stockholders' equity	20,850	41,862
Total liabilities and stockholders' equity	$158,110	$180,121

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	111,611,964	104,970,200
Common stock, shares outstanding	111,611,964	104,970,200

Statements_of_Operations

Statements of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues:	'	'
Collaborative agreement	$857	$857
Total revenues	857	857
Operating expenses:	'	'
Research and development	17,001	15,155
General and administrative	7,010	5,100
Total operating expenses	24,011	20,255
Loss from operations	-23,154	-19,398
Other income (expense):	'	'
Interest income	26	31
Interest and other expense	-1,770	-1
Total other income (expense)	-1,744	30
Net loss	($24,898)	($19,368)
Basic and diluted net loss per share	($0.23)	($0.21)
Basic and diluted shares used in computing net loss per share	109,249	90,336

Statements_of_Comprehensive_In

Statements of Comprehensive Income (Loss) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net loss	($24,898)	($19,368)
Other comprehensive loss	'	'
Unrealized gain (loss) on investment securities	9	-2
Other comprehensive gain (loss)	9	-2
Comprehensive income loss	($24,889)	($19,370)

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities	'	'
Net loss	($24,898)	($19,368)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:	'	'
Amortization of premium on securities available-for-sale	222	179
Accretion of debt discount	942	'
Amortization of debt issuance costs	10	'
Depreciation	8	76
Stock-based compensation	3,597	2,403
Deferred revenue	-857	-857
Changes in operating assets and liabilities:	'	'
Prepaid expenses and other current assets	-3	-507
Other assets	119	'
Accounts payable and accrued expenses	-1,189	-4,665
Deferred rent and lease incentives	105	-37
Net cash used in operating activities	-21,944	-22,776
Investing activities	'	'
Purchases of securities available-for-sale	-50,115	-18,577
Maturities of securities available-for-sale	11,250	29,965
Purchase of property and equipment	-28	'
Net cash provided by (used in) investing activities	-38,893	11,388
Financing activities	'	'
Proceeds from issuance of common stock	279	110
Net cash provided by financing activities	279	110
Net decrease in cash and cash equivalents	-60,558	-11,278
Cash and cash equivalents at beginning of period	98,121	78,332
Cash and cash equivalents at end of period	$37,563	$67,054

The_Company_and_Basis_of_Prese

The Company and Basis of Presentation	3 Months Ended
	Mar. 31, 2014
The Company and Basis of Presentation	'
	1. The Company and Basis of Presentation
	Organization
	Orexigen Therapeutics, Inc. (the “Company”), a Delaware corporation, is a biopharmaceutical company focused on the development of pharmaceutical product candidates for the treatment of obesity. The Company was incorporated in September 2002 and commenced operations in 2003.
	The Company’s primary activities since incorporation have been organizational activities, including recruiting personnel, conducting research and development, including clinical trials, and raising capital. In addition, the Company has experienced losses since its inception, and as of March 31, 2014, had an accumulated deficit of $539.4 million. The Company expects to continue to incur losses for at least the next several years. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure, and until that time, the Company may need to continue to raise additional equity or debt financing.
	Basis of Presentation
	The Company has prepared the accompanying unaudited financial statements in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Article 10-01 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by generally accepted accounting principles for complete financial statements. In the opinion of management, the accompanying unaudited financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s interim financial information.
	The balance sheet as of December 31, 2013 has been derived from the audited financial statements as of December 31, 2013 but does not include all information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. For more complete financial information, the accompanying unaudited financial statements and notes thereto should be read in conjunction with the audited financial statements for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	Research and Development Costs
	All research and development costs are charged to expense as incurred and consist principally of costs related to clinical trials managed by the Company’s contract research organizations, license fees and salaries and related benefits. Clinical trial costs are a significant component of research and development expenses. These costs are accrued based on estimates of work performed, and require estimates of total costs incurred based on patients enrolled, progress of clinical studies and other events. Clinical trial costs are subject to revision as the trials progress and revisions are charged to expense in the period in which they become known.
	Revenue Recognition
	The Company has entered into agreements with Takeda Pharmaceutical Company Limited (“Takeda”) and Cypress Bioscience, Inc. (“Cypress”) which contain multiple elements, including nonrefundable upfront fees, payments for reimbursement of research costs, payments associated with achieving specific development milestones and royalties based on specified percentages of net product sales, if any.
	Prior to the revised multiple element and milestone method of revenue recognition guidance adopted by the Company on January 1, 2011, nonrefundable, up-front license fees and milestone payments with standalone value that are not dependent on any future performance by the Company under the agreements were recognized as revenue upon the earlier of when payments are received or collection is assured, but were deferred if the Company has continuing performance obligations. If the Company had continuing involvement through contractual obligations under such agreements, such up-front fees were deferred and recognized over the period for which the Company continued to have a performance obligation. Both the Takeda and Cypress agreements had continuing obligations, and as a result the up-front fees were deferred upon receipt.
	Effective January 1, 2011, for multiple element agreements entered into or materially modified after December 31, 2010, the Company follows the provisions of Accounting Standards Update (“ASU”) No. 2009-13. In order to account for the multiple-element arrangements, the Company identifies the deliverables included within the agreement and evaluates which deliverables represent separate units of accounting. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation. A delivered item is considered a separate unit of accounting when the delivered item has value to the partner on a standalone basis based on the consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the research capabilities of the partner and the availability of research expertise in this field in the general marketplace. Arrangement consideration is allocated at the inception of the agreement to all identified units of accounting based on their relative selling price. The relative selling price for each deliverable is determined using vendor-specific objective evidence (“VSOE”) of selling price or third-party evidence of selling price if VSOE does not exist. If neither VSOE nor third-party evidence of selling price exists, we use our best estimate of the selling price for the deliverable. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable. The consideration received is allocated among the separate units of accounting, and the applicable revenue recognition criteria are applied to each of the separate units. Changes in the allocation of the sales price between delivered and undelivered elements can impact revenue recognition but do not change the total revenue recognized under any agreement. Upfront license fee payments are recognized upon delivery of the license if facts and circumstances dictate that the license has standalone value from the undelivered items, which generally include research and development services and the manufacture of drug products, the relative selling price allocation of the license is equal to or exceeds the upfront license fee, persuasive evidence of an arrangement exists, the Company’s price to the partner is fixed or determinable, and collectability is reasonably assured. The adoption of this new accounting standard did not have a material impact on the Company’s results of operations or financial position.
	Upfront license fee payments are deferred if facts and circumstances dictate that the license does not have standalone value. The determination of the length of the period over which to defer revenue is subject to judgment and estimation and can have a material impact on the amount of revenue recognized in a given period.
	The terms of the Company’s partnership agreements provide for milestone payments upon achievement of certain regulatory/development and sales-based events. Effective January 1, 2011, the Company adopted on a prospective basis the guidance under ASU No. 2010-17, “Revenue Recognition-Milestone Method.” Under the Milestone Method of accounting, the Company recognizes consideration that is contingent upon the achievement of a milestone as revenue in the period in which the milestone is achieved only if the milestone is substantive. A milestone is considered substantive when it meets all of the following three criteria: 1) the consideration is commensurate with either the entity’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, 2) the consideration relates solely to past performance, and 3) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity’s performance or on the occurrence of a specific outcome resulting from the entity’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to the Company. The adoption of this new accounting standard did not have a material impact on the Company’s results of operations or financial position.
	Royalties to be received based on sales of the Company’s licensed products by partners will be recognized as earned.
	Recently Issued Accounting Standards
	In July 2013, the Financial Accounting Standards Board (FASB) issued authoritative guidance for Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, which provides explicit guidance on the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The guidance is effective prospectively for fiscal years, and interim periods within those years, beginning after December 15, 2013. The Company adopted this guidance in the first quarter of 2014 and the adoption did not have a material impact on the Company’s financial statements.

Net_Loss_per_Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2014
Net Loss per Share	'
	3. Net Loss per Share
	Basic earnings per share (“EPS”) is calculated by dividing the net income or loss available to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted EPS is computed by dividing the net income available to common stockholders by the weighted average number of common shares outstanding for the period and the weighted average number of dilutive common stock equivalents outstanding for the period determined using the treasury-stock method.
	For purposes of this calculation, options are considered to be common stock equivalents and are only included in the calculation of diluted earnings per share when their effect is dilutive.
	(In thousands, except per share amounts)
		Three Months Ended
		March 31,
		2014			2013
	Numerator:
	Net loss attributable to common stockholders	$	(24,898	)	$	(19,368	)
	Denominator:
	Basic and diluted weighted average shares of common stock outstanding		109,249			90,336
	Basic and diluted net loss per share attributable to common stockholders	$	(0.23	)	$	(0.21	)
	Potentially outstanding anti-dilutive securities not included in diluted net loss per share calculation include the following:
	Shares underlying convertible senior notes		14,042			—
	Common stock warrants outstanding		11,370			29,604
	Common stock options outstanding		19,298			16,811
			44,710			46,415

Investment_Securities_Availabl

Investment Securities, Available-for-Sale	3 Months Ended
	Mar. 31, 2014
Investment Securities, Available-for-Sale	'
	4. Investment Securities, Available-for-Sale
	The Company invests its excess cash in investment securities, principally debt instruments of financial institutions, corporations with investment grade credit ratings and government agencies. A summary of the estimated fair value of investment securities, available-for-sale, is as follows at March 31, 2014 and December 31, 2013 (in thousands):
	March 31, 2014	Maturity in Years	Amortized		Unrealized
			Cost		Gains		Losses			Fair Value
	U.S. Treasury securities	Less than 1	$	1,000	$	—	$	—		$	1,000
	U.S. government agency securities	Less than 1		100,615		16		(8	)		100,623
	U.S. government agency securities	1 to 2		15,906		3		(4	)		15,905
	Total investment securities		$	117,521	$	19	$	(12	)	$	117,528
	December 31, 2013	Maturity in Years	Amortized		Unrealized					Fair Value
			Cost		Gains		Losses
	U.S. government agency securities	Less than 1	$	77,877	$	4	$	(7	)	$	77,874
	U.S. Treasury securities	Less than 1		1,001		—		—			1,001
	Total investment securities		$	78,878	$	4	$	(7	)	$	78,875
	Gross realized gains and losses on available-for-sale securities were immaterial during the three months ended March 31, 2014 and 2013.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
	5. Fair Value Measurements
	The fair values of the Company’s financial instruments are recorded using a hierarchal disclosure framework based upon the level of subjectivity of the inputs used in measuring assets and liabilities. The following table presents information about the Company’s financial assets measured at fair value on a recurring basis as of March 31, 2014, and indicates the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. The Company classifies money market funds as Level 1 assets. Fair values determined by Level 2 inputs utilize inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals. The Company classifies commercial paper holdings, U.S. Treasury securities, U.S. government agency securities and asset-backed security holdings as Level 2 assets. Level 3 inputs are unobservable inputs for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. The Company does not hold any Level 3 assets. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
	Assets that have recurring measurements are shown below (in thousands):
				Fair Value Measurement at Reporting Date Using
	Description	Balance as of		Quoted Prices in		Significant Other		Significant
		March  31, 2014		Active  Markets		Observable		Unobservable
				for Identical		Inputs (Level 2)		Inputs (Level 3)
				Assets (Level 1)
	Financial instruments owned:
	Money market funds	$	34,375	$	34,375	$	—	$	—
	U.S. Treasury securities		3,001		—		3,001		—
	U.S. government agency securities		116,528		—		116,528		—
	Total financial instruments owned	$	153,904	$	34,375	$	119,529	$	—

Property_and_Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2014
Property and Equipment	'
	6. Property and Equipment
	Property and equipment consist of the following (in thousands):
		Useful Life	March 31,			December 31,
		In Years	2014			2013
	Furniture and fixtures	5	$	1,079		$	1,079
	Computer equipment and software	3 to 5		396			422
	Leasehold improvements	5		557			557
	Asset under construction			546			518
				2,578			2,576
	Less accumulated depreciation and amortization			(1,928	)		(1,946	)
			$	650		$	630

Accrued_Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2014
Accrued Expenses	'
	7. Accrued Expenses
	Accrued expenses consist of the following (in thousands):
		March 31,		December 31,
		2014		2013
	Accrued compensation related expenses	$	1,842	$	4,774
	Accrued research and development expenses		1,552		1,273
	Accrued interest on convertible notes		1,037		220
	Accrued legal and professional expenses		553		355
	Other accrued liabilities		136		129
		$	5,120	$	6,751

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation	'
	8. Stock-Based Compensation
	Total stock-based compensation expense recognized during the three months ended March 31, 2014 and 2013 was comprised of the following (in thousands):
		Three Months Ended
		March  31,
		2014			2013
	General and administrative	$	2,476		$	1,738
	Research and development		1,121			665
		$	3,597		$	2,403
	The fair value of each option award is estimated on the date of grant using the Black-Scholes option valuation model. The following weighted-average assumptions were utilized for the calculations during each period:
		Three Months Ended
		March  31,
		2014			2013
	Expected life (in years)		5.6			6
	Expected volatility		107.3	%		92.7	%
	Risk-free interest rate		1.8	%		1.1	%
	Expected dividend yield		—			—

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
	9. Commitments and Contingencies
	Takeda Pharmaceutical Company Limited
	In September 2010, the Company entered into a collaboration agreement with Takeda to develop and commercialize NB32 (formerly referred to as Contrave) in the United States, Canada and Mexico. Under the terms of the collaboration agreement, the Company received a nonrefundable upfront cash payment of $50.0 million from Takeda and is eligible to receive additional payments of over $1.0 billion upon achieving certain anniversary, regulatory/development and sales-based milestones, including $100.0 million that can be achieved between the execution of the collaboration agreement and the first commercial sale of NB32 in the United States. The Company is also eligible to receive tiered royalty payments ranging from a minimum of 20% to a maximum of 35%, subject to customary reductions, on increasing levels of net sales in the United States, Canada and Mexico. In accordance with the Company’s continuing performance obligation of the collaboration, the upfront payment of $50.0 million is being deferred and recognized over 14.5 years, the estimated term of the agreement. For each of the three months ended March 31, 2014 and 2013, the Company recognized revenues under this agreement of $857,000. At March 31, 2014, deferred revenue under this agreement totaled $37.7 million.
	The Company has assessed milestones under the revised authoritative guidance for research and development milestones and determined that two regulatory/development milestone payments, $20.0 million due to the Company upon regulatory approval in the United States and $10.0 million due to the Company upon the delivery of launch supplies to Takeda, meet the definition of a milestone as: (1) they are events that can only be achieved in part on the Company’s performance or upon the occurrence of a specific outcome resulting in the Company’s performance, (2) there was substantive uncertainty at the date the agreement was entered into that the event will be achieved, and (3) they result in additional payments being due to the Company. The third regulatory/development milestone payment, $70.0 million due to the Company upon the first commercial sale in the United States, does not meet the definition of a milestone as Takeda is responsible for the commercialization of NB32. Sales-based milestone payments currently do not meet these criteria and will not be classified as milestones as their achievement is solely based on the performance of Takeda. The Company has determined that the anniversary milestones do not meet the definition of a milestone as the Company believes these payments are contingent solely upon the passage of time.
	2.75% Convertible Senior Notes due 2020
	In December 2013, the Company issued $115.0 million in aggregate principal amount of 2.75% convertible senior notes due 2020 (“2020 Notes”) in an offering to qualified institutional buyers conducted in accordance with Rule 144A under the Securities Act of 1933, as amended. Debt issuance costs of approximately $488,000 were primarily comprised of legal, accounting and other professional fees, the majority of which were recorded in other noncurrent assets and are being amortized to interest expense over the seven-year term of the 2020 Notes.
	Upon conversion, the 2020 Notes will be settled in shares of the Company’s common stock (together with cash in lieu of any fractional shares). However, if the Company receives stockholder approval in accordance with the Nasdaq Listing Standards, the Company will settle conversions of the 2020 Notes through payment or delivery, as the case may be, of cash, shares of the Company’s common stock or a combination thereof, at the Company’s election. The conversion rate for the Notes will initially be 122.1225 shares per $1,000 principal amount, which is equivalent to an initial conversion price of approximately $8.19 per share of common stock, and is subject to adjustment under the terms of the Notes.
	The 2020 Notes will mature on December 1, 2020, unless earlier repurchased or converted in accordance with their terms prior to such date. Prior to the close of business on the business day immediately preceding September 1, 2020, holders may convert all or a portion of their 2020 Notes only under the following circumstances: (1) during any fiscal quarter commencing after March 31, 2014, if, for at least 20 trading days (whether or not consecutive) during the 30 consecutive trading day period ending on the last trading day of the immediately preceding fiscal quarter, the last reported sale price of the Company’s common stock on such trading day is greater than or equal to 130% of the applicable conversion price on such trading day; (2) during the five consecutive business day period immediately following any ten consecutive trading day period (the “measurement period”) in which, for each trading day of that measurement period, the trading price per $1,000 principal amount of notes for such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock on such trading day and the applicable conversion rate on such trading day, or (3) upon the occurrence of specified corporate transactions. On and after September 1, 2020 until the close of business on the business day immediately preceding the maturity date, holders may convert all or a portion of their 2020 Notes at any time, regardless of the foregoing circumstances. Holders of the Notes will have the right to require the Company to repurchase all or some of their Notes at 100% of their principal amount, plus any accrued and unpaid interest, upon the occurrence of certain events.
	The Company pays 2.75% interest per annum on the principal amount of the 2020 Notes semi-annually in arrears in cash on June 1 and December 1 of each year, beginning on June 1, 2014. If a designated event, as defined in the indenture for the 2020 Notes, including, but not limited to, a change in control, certain mergers or liquidation, occurs prior to the maturity date, subject to certain limitations, holders of the Notes may require the Company to repurchase all or a portion of their 2020 Notes for cash at a repurchase price equal to 100% of the principal amount of the 2020 Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the repurchase date.
	The Company accounts separately for the liability and equity components of the 2020 Notes in accordance with authoritative guidance for convertible debt instruments that may be settled in cash upon conversion. The guidance requires the carrying amount of the liability component to be estimated by measuring the fair value of a similar liability that does not have an associated conversion feature. Because the Company has no outstanding non-convertible public debt, the Company determined that senior, unsecured corporate bonds traded on the market represent a similar liability to the 2020 Notes without the conversion option. The Company estimated the implied interest rate of its 2020 Notes to be 8.69%, assuming no conversion option. Assumptions used in the estimate represent what market participants would use in pricing the liability component, including market interest rates, credit standing, and yield curves, all of which are defined as Level 2 observable inputs. The estimated implied interest rate was applied to the 2020 Notes, which resulted in a fair value of the liability component of $79.7 million upon issuance, calculated as the present value of implied future payments based on the $115.0 million in aggregate principal amount. The $31.3 million difference between the cash proceeds of $111.0 million and the estimated fair value of the liability component was recorded in additional paid-in capital as the 2020 Notes were not considered redeemable.
	A summary of the liability and equity components of the 2020 Notes is as follows at March 31, 2014 and December 31, 2013 (in thousands):
		March 31,			December 31,
		2014			2013
	Principal amount of senior convertible notes outstanding	$	115,000		$	115,000
	Unamortized discount of liability component		(34,027	)		(34,969	)
	Long term convertible debt	$	80,973		$	80,031
	Remaining amortization period of discount on the liability component		6.8 years			7.0 years
	Carrying value of equity component, net of issuance costs	$	31,178		$	31,178

Litigation

Litigation	3 Months Ended
	Mar. 31, 2014
Litigation	'
	10. Litigation
	In May 2013, the Company received a shareholder demand alleging that certain option grants to the Company’s President and Chief Executive Officer, Michael A. Narachi, the Company’s Chief Business Officer and acting-Chief Financial Officer, Joseph P. Hagan, and the Company’s Senior Vice President, General Counsel and Secretary, Heather D. Turner, in 2011 were granted in excess of the 1,500,000 share limit set forth in Section 3.3 of the 2007 Plan as to the number of shares of the Company’s common stock with respect to which one or more stock awards may be granted to any one eligible participant during any of the Company’s fiscal years. The Company refers to this limit as the 162(m) Award Limit. The Company’s board of directors established a demand review committee composed of independent directors to conduct an investigation with respect to the shareholder demand and to make recommendations to the Company’s board of directors. The demand review committee engaged independent counsel as part of its investigation and evaluated (1) the terms of the 2007 Plan, (2) the initial issuance procedures for the option grants to Mr. Narachi, Mr. Hagan and Ms. Turner during 2011, (3) the authority available to the compensation committee of the Company’s board of directors under its charter and the 2007 Plan, (4) the expectations of the award recipients and (5) the intent of the Company’s board of directors and the compensation committee regarding the availability of an exemption from the deductibility limitations of Section 162(m) of the Internal Revenue Code for such option grants. Following its investigation, the demand review committee determined that the 162(m) Award Limit first became effective as of June 2, 2011, and that, therefore, awards granted under the 2007 Plan prior to June 2, 2011, did not count toward the 162(m) Award Limit. The demand review committee determined that the awards granted to Mr. Hagan between June 2, 2011 and December 31, 2011 did not exceed the 162(m) Award Limit. The demand review committee further determined that the options granted to Mr. Narachi and Ms. Turner, including the portion of such awards in excess of the 162(m) Award Limit, were validly approved under the 2007 Plan, although the portion of those awards in excess of the 162(m) Award Limit does not qualify as performance-based compensation under Section 162(m). In September 2013, the compensation committee amended the 2007 Plan, with the approval of the Company’s board of directors, to take the following actions: (1) to clarify that the 162(m) Award Limit only applies to awards or the portion thereof intended to qualify as performance-based compensation under Section 162(m); and (2) to confirm that the compensation committee has the authority to make awards in excess of the 162(m) Award Limit, which the Company refers to as the Plan Amendment. The Plan Amendment is deemed effective as of June 10, 2011, consistent with the authority of the compensation committee as administrator of the 2007 Plan as of that date. Any grants under the 2007 Plan in excess of the 162(m) Award Limit are not intended to qualify as performance-based compensation under Section 162(m).
	On December 6, 2013, a plaintiff claiming to be a shareholder of the Company filed a derivative lawsuit purportedly on behalf of the Company against certain of the Company’s officers and the members of the Company’s board of directors, in the Superior Court for the State of California, County of San Diego, captioned Wilkin v. Narachi, et al. On December 9, 2013, the same shareholder who made a demand on the board in May 2013 filed a derivative lawsuit purportedly on the Company’s behalf against certain of the Company’s officers and current and former members of the Company’s board of directors in the United States District Court, for the Southern District of California, captioned Turgeman v. Narachi, et al. Both of the lawsuits assert claims for breach of fiduciary duty, waste and unjust enrichment based on, among other things, the alleged grant of stock options to certain officers in excess of the 162(m) Award Limit, repricing stock options allegedly in violation of the Company’s equity incentive plan, the board of directors’ conduct in responding to the May 2013 shareholder demand, and making allegedly false and misleading statements. Both of the lawsuits seek, among other things, declaratory relief, corporate governance reforms, rescission of certain stock option awards, rescission of the Plan Amendment, injunctive relief, damages, restitution, disgorgement and attorney’s fees. Although the Company’s management believes that the claims lack merit and intends to defend against them vigorously, there are uncertainties inherent in any litigation and the Company cannot predict the outcome. However, the Company does not believe that the outcome would have a material adverse effect on the Company.
	It is possible that securities class action litigation may be brought against the Company following stock price declines related to the release of information regarding the Company’s NB32 NDA or clinical trial results, including the Light Study or related to the matters alleged in the May 2013 shareholder demand and/or the Plan Amendment. Any adverse determination in such litigation could subject the Company to significant liabilities.

The_Company_and_Basis_of_Prese1

The Company and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2014
Organization	'
	Organization
	Orexigen Therapeutics, Inc. (the “Company”), a Delaware corporation, is a biopharmaceutical company focused on the development of pharmaceutical product candidates for the treatment of obesity. The Company was incorporated in September 2002 and commenced operations in 2003.
	The Company’s primary activities since incorporation have been organizational activities, including recruiting personnel, conducting research and development, including clinical trials, and raising capital. In addition, the Company has experienced losses since its inception, and as of March 31, 2014, had an accumulated deficit of $539.4 million. The Company expects to continue to incur losses for at least the next several years. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure, and until that time, the Company may need to continue to raise additional equity or debt financing.
Basis of Presentation	'
	Basis of Presentation
	The Company has prepared the accompanying unaudited financial statements in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Article 10-01 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by generally accepted accounting principles for complete financial statements. In the opinion of management, the accompanying unaudited financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s interim financial information.
	The balance sheet as of December 31, 2013 has been derived from the audited financial statements as of December 31, 2013 but does not include all information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. For more complete financial information, the accompanying unaudited financial statements and notes thereto should be read in conjunction with the audited financial statements for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
Research and Development Costs	'
	Research and Development Costs
	All research and development costs are charged to expense as incurred and consist principally of costs related to clinical trials managed by the Company’s contract research organizations, license fees and salaries and related benefits. Clinical trial costs are a significant component of research and development expenses. These costs are accrued based on estimates of work performed, and require estimates of total costs incurred based on patients enrolled, progress of clinical studies and other events. Clinical trial costs are subject to revision as the trials progress and revisions are charged to expense in the period in which they become known.
Revenue Recognition	'
	Revenue Recognition
	The Company has entered into agreements with Takeda Pharmaceutical Company Limited (“Takeda”) and Cypress Bioscience, Inc. (“Cypress”) which contain multiple elements, including nonrefundable upfront fees, payments for reimbursement of research costs, payments associated with achieving specific development milestones and royalties based on specified percentages of net product sales, if any.
	Prior to the revised multiple element and milestone method of revenue recognition guidance adopted by the Company on January 1, 2011, nonrefundable, up-front license fees and milestone payments with standalone value that are not dependent on any future performance by the Company under the agreements were recognized as revenue upon the earlier of when payments are received or collection is assured, but were deferred if the Company has continuing performance obligations. If the Company had continuing involvement through contractual obligations under such agreements, such up-front fees were deferred and recognized over the period for which the Company continued to have a performance obligation. Both the Takeda and Cypress agreements had continuing obligations, and as a result the up-front fees were deferred upon receipt.
	Effective January 1, 2011, for multiple element agreements entered into or materially modified after December 31, 2010, the Company follows the provisions of Accounting Standards Update (“ASU”) No. 2009-13. In order to account for the multiple-element arrangements, the Company identifies the deliverables included within the agreement and evaluates which deliverables represent separate units of accounting. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation. A delivered item is considered a separate unit of accounting when the delivered item has value to the partner on a standalone basis based on the consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the research capabilities of the partner and the availability of research expertise in this field in the general marketplace. Arrangement consideration is allocated at the inception of the agreement to all identified units of accounting based on their relative selling price. The relative selling price for each deliverable is determined using vendor-specific objective evidence (“VSOE”) of selling price or third-party evidence of selling price if VSOE does not exist. If neither VSOE nor third-party evidence of selling price exists, we use our best estimate of the selling price for the deliverable. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable. The consideration received is allocated among the separate units of accounting, and the applicable revenue recognition criteria are applied to each of the separate units. Changes in the allocation of the sales price between delivered and undelivered elements can impact revenue recognition but do not change the total revenue recognized under any agreement. Upfront license fee payments are recognized upon delivery of the license if facts and circumstances dictate that the license has standalone value from the undelivered items, which generally include research and development services and the manufacture of drug products, the relative selling price allocation of the license is equal to or exceeds the upfront license fee, persuasive evidence of an arrangement exists, the Company’s price to the partner is fixed or determinable, and collectability is reasonably assured. The adoption of this new accounting standard did not have a material impact on the Company’s results of operations or financial position.
	Upfront license fee payments are deferred if facts and circumstances dictate that the license does not have standalone value. The determination of the length of the period over which to defer revenue is subject to judgment and estimation and can have a material impact on the amount of revenue recognized in a given period.
	The terms of the Company’s partnership agreements provide for milestone payments upon achievement of certain regulatory/development and sales-based events. Effective January 1, 2011, the Company adopted on a prospective basis the guidance under ASU No. 2010-17, “Revenue Recognition-Milestone Method.” Under the Milestone Method of accounting, the Company recognizes consideration that is contingent upon the achievement of a milestone as revenue in the period in which the milestone is achieved only if the milestone is substantive. A milestone is considered substantive when it meets all of the following three criteria: 1) the consideration is commensurate with either the entity’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, 2) the consideration relates solely to past performance, and 3) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity’s performance or on the occurrence of a specific outcome resulting from the entity’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to the Company. The adoption of this new accounting standard did not have a material impact on the Company’s results of operations or financial position.
	Royalties to be received based on sales of the Company’s licensed products by partners will be recognized as earned.
Recently Issued Accounting Standards	'
	Recently Issued Accounting Standards
	In July 2013, the Financial Accounting Standards Board (FASB) issued authoritative guidance for Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, which provides explicit guidance on the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The guidance is effective prospectively for fiscal years, and interim periods within those years, beginning after December 15, 2013. The Company adopted this guidance in the first quarter of 2014 and the adoption did not have a material impact on the Company’s financial statements.

Net_Loss_per_Share_Tables

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2014
Diluted Earnings per Share	'
	For purposes of this calculation, options are considered to be common stock equivalents and are only included in the calculation of diluted earnings per share when their effect is dilutive.
	(In thousands, except per share amounts)
		Three Months Ended
		March 31,
		2014			2013
	Numerator:
	Net loss attributable to common stockholders	$	(24,898	)	$	(19,368	)
	Denominator:
	Basic and diluted weighted average shares of common stock outstanding		109,249			90,336
	Basic and diluted net loss per share attributable to common stockholders	$	(0.23	)	$	(0.21	)
	Potentially outstanding anti-dilutive securities not included in diluted net loss per share calculation include the following:
	Shares underlying convertible senior notes		14,042			—
	Common stock warrants outstanding		11,370			29,604
	Common stock options outstanding		19,298			16,811
			44,710			46,415

Investment_Securities_Availabl1

Investment Securities, Available-for-Sale (Tables)	3 Months Ended
	Mar. 31, 2014
Estimated Fair Value of Investment Securities, Available-for-Sale	'
	A summary of the estimated fair value of investment securities, available-for-sale, is as follows at March 31, 2014 and December 31, 2013 (in thousands):
	March 31, 2014	Maturity in Years	Amortized		Unrealized
			Cost		Gains		Losses			Fair Value
	U.S. Treasury securities	Less than 1	$	1,000	$	—	$	—		$	1,000
	U.S. government agency securities	Less than 1		100,615		16		(8	)		100,623
	U.S. government agency securities	1 to 2		15,906		3		(4	)		15,905
	Total investment securities		$	117,521	$	19	$	(12	)	$	117,528
	December 31, 2013	Maturity in Years	Amortized		Unrealized					Fair Value
			Cost		Gains		Losses
	U.S. government agency securities	Less than 1	$	77,877	$	4	$	(7	)	$	77,874
	U.S. Treasury securities	Less than 1		1,001		—		—			1,001
	Total investment securities		$	78,878	$	4	$	(7	)	$	78,875

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Assets Measured at Fair Value on Recurring Basis	'
	Assets that have recurring measurements are shown below (in thousands):
				Fair Value Measurement at Reporting Date Using
	Description	Balance as of		Quoted Prices in		Significant Other		Significant
		March  31, 2014		Active  Markets		Observable		Unobservable
				for Identical		Inputs (Level 2)		Inputs (Level 3)
				Assets (Level 1)
	Financial instruments owned:
	Money market funds	$	34,375	$	34,375	$	—	$	—
	U.S. Treasury securities		3,001		—		3,001		—
	U.S. government agency securities		116,528		—		116,528		—
	Total financial instruments owned	$	153,904	$	34,375	$	119,529	$	—

Property_and_Equipment_Tables

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2014
Property and Equipment	'
	Property and equipment consist of the following (in thousands):
		Useful Life	March 31,			December 31,
		In Years	2014			2013
	Furniture and fixtures	5	$	1,079		$	1,079
	Computer equipment and software	3 to 5		396			422
	Leasehold improvements	5		557			557
	Asset under construction			546			518
				2,578			2,576
	Less accumulated depreciation and amortization			(1,928	)		(1,946	)
			$	650		$	630

Accrued_Expenses_Tables

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2014
Accrued Expenses	'
	Accrued expenses consist of the following (in thousands):
		March 31,		December 31,
		2014		2013
	Accrued compensation related expenses	$	1,842	$	4,774
	Accrued research and development expenses		1,552		1,273
	Accrued interest on convertible notes		1,037		220
	Accrued legal and professional expenses		553		355
	Other accrued liabilities		136		129
		$	5,120	$	6,751

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation Expense	'
	Total stock-based compensation expense recognized during the three months ended March 31, 2014 and 2013 was comprised of the following (in thousands):
		Three Months Ended
		March  31,
		2014			2013
	General and administrative	$	2,476		$	1,738
	Research and development		1,121			665
		$	3,597		$	2,403
Weighted Average Assumptions	'
	The following weighted-average assumptions were utilized for the calculations during each period:
		Three Months Ended
		March  31,
		2014			2013
	Expected life (in years)		5.6			6
	Expected volatility		107.3	%		92.7	%
	Risk-free interest rate		1.8	%		1.1	%
	Expected dividend yield		—			—

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2014
Summary of Liability and Equity Components	'
	A summary of the liability and equity components of the 2020 Notes is as follows at March 31, 2014 and December 31, 2013 (in thousands):
		March 31,			December 31,
		2014			2013
	Principal amount of senior convertible notes outstanding	$	115,000		$	115,000
	Unamortized discount of liability component		(34,027	)		(34,969	)
	Long term convertible debt	$	80,973		$	80,031
	Remaining amortization period of discount on the liability component		6.8 years			7.0 years
	Carrying value of equity component, net of issuance costs	$	31,178		$	31,178

The_Company_and_Basis_of_Prese2

The Company and Basis of Presentation - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Basis Of Presentation And Organization [Line Items]	'	'
Accumulated deficit	($539,373)	($514,475)

Diluted_Earnings_per_Share_Det

Diluted Earnings per Share (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Numerator:	'	'
Net loss attributable to common stockholders	($24,898)	($19,368)
Denominator:	'	'
Basic and diluted weighted average shares of common stock outstanding	109,249	90,336
Basic and diluted net loss per share attributable to common stockholders	($0.23)	($0.21)
Potentially outstanding anti-dilutive securities not included in diluted net loss per share calculation include the following:	'	'
Common stock warrants/ options outstanding	44,710	46,415
Convertible Senior Notes	'	'
Potentially outstanding anti-dilutive securities not included in diluted net loss per share calculation include the following:	'	'
Common stock warrants/ options outstanding	14,042	'
Warrants	'	'
Potentially outstanding anti-dilutive securities not included in diluted net loss per share calculation include the following:	'	'
Common stock warrants/ options outstanding	11,370	29,604
Stock Options	'	'
Potentially outstanding anti-dilutive securities not included in diluted net loss per share calculation include the following:	'	'
Common stock warrants/ options outstanding	19,298	16,811

Estimated_Fair_Value_of_Invest

Estimated Fair Value of Investment Securities, Available-for-Sale (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$117,521	$78,878
Unrealized Gains	19	4
Unrealized Losses	-12	-7
Fair Value	117,528	78,875
U.S. Treasury Securities | Mature In Less Than One Year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Maturity in Years	'Less than 1	'Less than 1
Amortized Cost	1,000	1,001
Fair Value	1,000	1,001
U.S. Government Agency Securities | Mature In Less Than One Year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Maturity in Years	'Less than 1	'Less than 1
Amortized Cost	100,615	77,877
Unrealized Gains	16	4
Unrealized Losses	-8	-7
Fair Value	100,623	77,874
U.S. Government Agency Securities | Mature In One To Two Years	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Maturity in Years	'1 to 2	'
Amortized Cost	15,906	'
Unrealized Gains	3	'
Unrealized Losses	-4	'
Fair Value	$15,905	'

Assets_that_have_Recurring_Mea

Assets that have Recurring Measurements (Detail) (Fair Value, Measurements, Recurring, USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	$153,904
Money market funds	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	34,375
U.S. Treasury Securities	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	3,001
U.S. Government Agency Securities	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	116,528
Quoted Prices in Active Markets for Identical Assets (Level 1)	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	34,375
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]	'
Total financial instruments owned	34,375
Significant Other Observable Inputs (Level 2)	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	119,529
Significant Other Observable Inputs (Level 2) | U.S. Treasury Securities	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	3,001
Significant Other Observable Inputs (Level 2) | U.S. Government Agency Securities	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'
Total financial instruments owned	$116,528

Property_and_Equipment_Detail

Property and Equipment (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]	'	'
Gross total	$2,578	$2,576
Less accumulated depreciation and amortization	-1,928	-1,946
Property and equipment, net	650	630
Furniture and Fixtures	'	'
Property, Plant and Equipment [Line Items]	'	'
Useful Life In Years	'5 years	'
Gross total	1,079	1,079
Computer Equipment and Software	'	'
Property, Plant and Equipment [Line Items]	'	'
Gross total	396	422
Computer Equipment and Software | Minimum	'	'
Property, Plant and Equipment [Line Items]	'	'
Useful Life In Years	'3 years	'
Computer Equipment and Software | Maximum	'	'
Property, Plant and Equipment [Line Items]	'	'
Useful Life In Years	'5 years	'
Leasehold Improvements	'	'
Property, Plant and Equipment [Line Items]	'	'
Useful Life In Years	'5 years	'
Gross total	557	557
Asset under Construction	'	'
Property, Plant and Equipment [Line Items]	'	'
Gross total	$546	$518

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Payable and Accrued Liabilities [Line Items]	'	'
Accrued compensation related expenses	$1,842	$4,774
Accrued research and development expenses	1,552	1,273
Accrued interest on convertible notes	1,037	220
Accrued legal and professional expenses	553	355
Other accrued liabilities	136	129
Accrued expenses	$5,120	$6,751

Stock_Based_Compensation_Expen

Stock- Based Compensation Expense (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Total Stock-Based Compensation Expense	$3,597	$2,403
General and Administrative	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Total Stock-Based Compensation Expense	2,476	1,738
Research and Development	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Total Stock-Based Compensation Expense	$1,121	$665

Weighted_Average_Assumptions_o

Weighted Average Assumptions of Options Granted (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Expected life (in years)	'5 years 7 months 6 days	'6 years
Expected volatility	107.30%	92.70%
Risk-free interest rate	1.80%	1.10%
Expected dividend yield	'	'

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended						3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
	2.75% convertible senior notes due 2020	2.75% convertible senior notes due 2020	2.75% convertible senior notes due 2020	During Any Fiscal Quarter Commencing After March 31, 2014	During Any Fiscal Quarter Commencing After March 31, 2014	During The Five Consecutive Business Day Period	During The Five Consecutive Business Day Period	Collaborative Arrangement	Collaborative Arrangement
			Significant Other Observable Inputs (Level 2)	2.75% convertible senior notes due 2020	2.75% convertible senior notes due 2020	2.75% convertible senior notes due 2020	2.75% convertible senior notes due 2020	Takeda Pharmaceutical Company Limited	Takeda Pharmaceutical Company Limited
					Minimum		Maximum
					D
Commitments and Contingencies [Line Items]	'	'	'	'	'	'	'	'	'
Nonrefundable upfront cash payment received	'	'	'	'	'	'	'	$50,000,000	'
Additional payments eligible	'	'	'	'	'	'	'	1,000,000,000	'
Amount achieved between the execution of the collaboration agreement and the first commercial sale	'	'	'	'	'	'	'	100,000,000	'
Tiered royalty payments, Minimum	'	'	'	'	'	'	'	20.00%	'
Tiered royalty payments, Maximum	'	'	'	'	'	'	'	35.00%	'
Deferred upfront payment	'	'	'	'	'	'	'	50,000,000	'
Estimated term of the agreement	'	'	'	'	'	'	'	'14 years 6 months	'
Revenue recognized	'	'	'	'	'	'	'	857,000	857,000
Deferred revenue	'	'	'	'	'	'	'	37,700,000	'
Milestone payments due to company upon regulatory approval	'	'	'	'	'	'	'	20,000,000	'
Milestone payments due to the Company upon the delivery of launch supplies	'	'	'	'	'	'	'	10,000,000	'
Milestone payment due to the Company upon the first commercial sale	'	'	'	'	'	'	'	70,000,000	'
Aggregate principal amount convertible notes	'	115,000,000	'	'	'	'	'	'	'
Interest rate	'	2.75%	'	'	'	'	'	'	'
Debt Issuance Cost	'	488,000	'	'	'	'	'	'	'
Debt Instrument, Term	'	'7 years	'	'	'	'	'	'	'
Convertible notes initial conversion rate	'	122.1225	'	'	'	'	'	'	'
Convertible notes, initial conversion rate principal amount	'	1,000	'	'	'	'	'	'	'
Convertible notes, initial conversion price per share	'	$8.19	'	'	'	'	'	'	'
Debt instrument, maturity date	'	1-Dec-20	'	'	'	'	'	'	'
Threshold trading days	'	'	'	'	20	'	'	'	'
Threshold consecutive trading days	'	'	'	'30 days	'	'10 days	'	'	'
Convertible, threshold percentage of stock price trigger	'	'	'	'	130.00%	'	98.00%	'	'
Number of business day period	'	'	'	'	'	'5 days	'	'	'
Required repurchase percentage on principal amount	'	'	'	'	'	100.00%	'	'	'
Repurchase of notes description	'On and after September 1, 2020 until the close of business on the business day immediately preceding the maturity date, holders may convert all or a portion of their 2020 Notes at any time, regardless of the foregoing circumstances.	'	'	'	'	'	'	'	'
Debt instrument, interest payment terms	'The Company pays 2.75% interest per annum on the principal amount of the 2020 Notes semi-annually in arrears in cash on June 1 and December 1 of each year, beginning on June 1, 2014.	'	'	'	'	'	'	'	'
Estimated implied interest rate	'	'	8.69%	'	'	'	'	'	'
Fair value of liability component upon issuance	'	'	79,700,000	'	'	'	'	'	'
Carrying value of equity component, net of issuance costs	31,178,000	31,178,000	31,300,000	'	'	'	'	'	'
Proceeds from issuance of convertible notes	'	'	$111,000,000	'	'	'	'	'	'

Equity_and_Liability_Component

Equity and Liability Components of Notes (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Disclosure Equity Components [Line Items]	'	'
Long term convertible debt	$80,973	$80,031
2.75% convertible senior notes due 2020	'	'
Disclosure Equity Components [Line Items]	'	'
Principal amount of senior convertible notes outstanding	115,000	115,000
Unamortized discount of liability component	-34,027	-34,969
Long term convertible debt	80,973	80,031
Remaining amortization period of discount on the liability component	'6 years 9 months 18 days	'7 years
Carrying value of equity component, net of issuance costs	$31,178	$31,178

Litigation_Additional_Informat

Litigation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
Litigation [Line Items]	'
Share based compensation plan award maximum number of shares granted per eligible participant	1,500,000