Portola Pharmaceuticals (PTLA) 10-Q 13 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014
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	'PTLA
Entity Registrant Name	'PORTOLA PHARMACEUTICALS INC
Entity Central Index Key	'0001269021
Current Fiscal Year End Date	'--12-31
Entity Filer Category	'Non-accelerated Filer
Entity Common Stock, Shares Outstanding	41,121,291

Condensed_Balance_Sheets

Condensed Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$63,001	$117,773
Short-term investments	198,433	150,892
Receivables from collaborations	6,664	309
Prepaid expenses and other current assets	5,168	3,733
Total current assets	273,266	272,707
Property and equipment, net	2,670	2,600
Long-term investments	44,269	50,371
Other assets	34	53
Total assets	320,239	325,731
Current liabilities:	'	'
Accounts payable	7,380	3,232
Accrued compensation and employee benefits	1,649	2,569
Accrued and other liabilities	14,990	17,796
Deferred revenue, current portion	8,779	1,958
Total current liabilities	32,798	25,555
Deferred revenue, long-term	17,060	3,253
Other long-term liabilities	1,189	588
Total liabilities	51,047	29,396
Stockholders’ equity:	'	'
Preferred stock, $0.001 par value, 5,000,000 shares authorized at March 31, 2014 and December 31, 2013; 0 shares issued and outstanding at March 31, 2014 and December 31, 2013	'	'
Common stock, $0.001 par value, 100,000,000 shares authorized at March 31, 2014 and December 31, 2013; 41,120,789 and 40,915,130 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	41	41
Additional paid-in capital	585,522	581,911
Accumulated deficit	-316,398	-285,672
Accumulated other comprehensive income	27	55
Total stockholders’ equity	269,192	296,335
Total liabilities and stockholders’ equity	$320,239	$325,731

Condensed_Balance_Sheets_Paren

Condensed Balance Sheets (Parenthetical) (USD $)	Mar. 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	41,120,789	40,915,130
Common stock, shares outstanding	41,120,789	40,915,130

Condensed_Statements_of_Operat

Condensed Statements of Operations (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Collaboration and license revenue	$2,372	$3,108
Operating expenses:	'	'
Research and development	28,155	17,722
General and administrative	5,241	3,039
Total operating expenses	33,396	20,761
Loss from operations	-31,024	-17,653
Interest and other income (expense), net	298	-489
Net loss	($30,726)	($18,142)
Net loss per share attributable to common stockholders:	'	'
Basic and diluted	($0.75)	($12.94)
Shares used to compute net loss per share attributable to common stockholders:	'	'
Basic and diluted	41,001,623	1,401,677

Condensed_Statements_of_Compre

Condensed Statements of Comprehensive Loss (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net loss	($30,726)	($18,142)
Other comprehensive loss:	'	'
Unrealized loss on available-for-sale securities, net of tax	-28	-13
Total comprehensive loss	($30,754)	($18,155)

Condensed_Statements_of_Cash_F

Condensed Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities	'	'
Net loss	($30,726)	($18,142)
Adjustments to reconcile net loss to cash used in operating activities:	'	'
Depreciation and amortization	358	336
Amortization of premium on investment securities	944	445
Stock-based compensation expense	2,302	713
Revaluation of convertible preferred stock warrant liability	'	-35
Unrealized (gain) loss on foreign currency forward contracts	-17	534
Changes in operating assets and liabilities:	'	'
Receivables from collaborations	145	-296
Prepaid expenses and other current assets	-1,418	417
Other assets	19	-971
Accounts payable	4,115	2,068
Accrued compensation and employee benefits	-882	-791
Accrued and other liabilities	-2,806	1,879
Deferred revenue	14,128	1,892
Other long-term liabilities	601	-209
Net cash used in operating activities	-13,237	-12,160
Investing activities	'	'
Purchases of property and equipment	-395	-293
Purchases of investments	-76,555	-11,867
Proceeds from sales of investments	3,000	2,500
Proceeds from maturities of investments	31,145	26,009
Net cash (used in) provided by investing activities	-42,805	16,349
Financing activities	'	'
Proceeds from issuance of common stock, including early exercise of stock options	1,270	164
Net cash provided by financing activities	1,270	164
Net (decrease) increase in cash and cash equivalents	-54,772	4,353
Cash and cash equivalents at beginning of year	117,773	53,613
Cash and cash equivalents at end of year	$63,001	$57,966

Organization

Organization	3 Months Ended
	Mar. 31, 2014
Organization	'
	1. Organization
	Portola Pharmaceuticals, Inc. (the “Company” or “we” or “our” or “us”) is a biopharmaceutical company focused on the development and commercialization of product candidates in the fields of thrombosis and other hematologic diseases. We were incorporated in September 2003 in Delaware. Our headquarters and operations are located in South San Francisco, California and we operate in one segment.
	Our two lead programs address unmet medical needs in the area of thrombosis, or blood clots, for patients who currently have limited or no approved treatment options. Our lead compound, Betrixaban, is a novel oral once-daily inhibitor of Factor Xa in Phase 3 development for extended duration prophylaxis, or preventive treatment, of a form of thrombosis known as venous thromboembolism, in acute medically ill patients. Our second lead development candidate, Andexanet alfa, is a recombinant protein designed to reverse the anticoagulant activity in patients treated with a Factor Xa inhibitor who suffer a major bleeding episode or undergo emergency surgery. Our third product candidate Cerdulatinib, formerly PRT2070, is an orally available kinase inhibitor being developed for hematologic, or blood, cancers and inflammatory disorders. We also have a program for other selective Syk inhibitors, which is being developed in partnership with Biogen Idec, Inc.

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
	Basis of Presentation
	The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”), and following the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, that are necessary for a fair statement of the Company’s financial information. The results of operations for the three months ended March 31, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014. The condensed balance sheet as of December 31, 2013 has been derived from audited financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements.
	The accompanying condensed financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K filed March 3, 2014 with the SEC.
	Use of Estimates
	The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the condensed financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, clinical trial accruals, fair value of assets and liabilities, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results may differ from those estimates.
	Cash and Cash Equivalents
	Cash and cash equivalents consist of cash and other highly liquid investments with original maturities of three months or less from the date of purchase.
	Investments
	All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and were reported as a component of accumulated comprehensive income. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income (expense), net. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest and other income (expense), net.
	Customer Concentration
	Customers whose collaborative research and development revenue accounted for 10% or more of total revenues were as follows:
		Three Months Ended
		March 31,
		2014			2013
	Bristol-Myers Squibb Company and Pfizer Inc.		19	%		64	%
	Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		38	%		36	%
	Daiichi Sankyo, Inc		40	%		—
	Revenue Recognition
	We generate revenue from collaboration and license agreements for the development and commercialization of our products. Collaboration and license agreements may include non-refundable or partially refundable upfront license fees, partial or complete reimbursement of research and development costs, contingent consideration payments based on the achievement of defined collaboration objectives and royalties on sales of commercialized products. Our performance obligations under our collaborations include the transfer of intellectual property rights (licenses), obligations to provide research and development services and related materials, obligations to manufacture and supply of Andexanet alfa and obligations to participate on certain development and/or commercialization committees with the collaborators.
	Payments that are contingent upon achievement of a substantive milestone are recognized in their entirety in the period in which the milestone is achieved. Milestones are defined as an event that can only be achieved based on our performance and there is substantive uncertainty about whether the event will be achieved at the inception of the arrangement. Events that are contingent only on the passage of time or only on counterparty performance are not considered milestones subject to this guidance. Further, the amounts received must relate solely to prior performance, be reasonable relative to all of the deliverables and payment terms within the agreement and commensurate with our performance to achieve the milestone after commencement of the agreement. Payments contingent upon achievement of events that are not considered substantive milestones are allocated to the respective arrangements unit of accounting when received and recognized as revenue based on the revenue recognition policy for that unit of accounting.
	Amounts from sales of licenses are recognized as revenue, as licensing of intellectual property is one of our principal or major ongoing activities. Amounts received as funding of research and development activities are recognized as revenue if the collaboration arrangement involves the sale of our research or development services at amounts that exceed our cost. However, such funding is recognized as a reduction in research and development expense when we engage in a research and development project jointly with another entity, with both entities participating in project activities and sharing costs and potential benefits of the arrangement.
	Amounts related to research and development funding are recognized as the related services or activities are performed, in accordance with the contract terms. Payments may be made to or by us based on the number of full-time equivalent researchers assigned to the collaboration project and the related research and development expenses incurred.
	Foreign Currency Transactions and Hedging
	We have transactions denominated in foreign currencies, primarily the Euro, and, as a result, are exposed to changes in foreign currency exchange rates. We manage a portion of these cash flow exposures through the purchase of Euros and the use of foreign currency forward contracts. Our foreign currency forward contracts are not designated as hedges for accounting purposes. Gains or losses on foreign currency forward contracts are intended to offset gains or losses on the underlying net exposures in an effort to reduce the earnings and cash flow volatility resulting from fluctuating foreign currency exchange rates. Foreign currencies and our foreign currency forward contracts are marked to market at the end of each period and recorded as gains and losses in the condensed statements of operations.
	Our foreign exchange forward contracts expose us to credit risk to the extent that the counterparty, a major financial institution, is unable to meet the terms of the agreement. Our management does not expect material losses as a result of defaults by the counterparty.
	Net Loss per Share Attributable to Common Stockholders
	Basic and diluted net loss per share attributable to common stockholders is calculated in conformity with the two-class method required for companies with participating securities. Under the two-class method, in periods when we have net income, basic net income attributable to common stockholders is determined by allocating undistributed earnings, calculated as net income less current period convertible preferred stock noncumulative dividends, between the common stock and the convertible preferred stock. In computing diluted net income attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods when we have incurred a net loss, convertible preferred stock, options and warrants to purchase common stock and convertible preferred stock warrants are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
	3. Fair Value Measurements
	Financial assets and liabilities are recorded at fair value. The carrying amounts of certain of our financial instruments, including cash and cash equivalents, investments, receivables from collaborators, prepaid expenses and other current assets and accounts payable, approximate their fair value due to their short term nature. The accounting guidance for fair value provides a framework for measuring fair value, clarifies the definition of fair value, and expands disclosures regarding fair value measurements. Fair value is defined as 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 reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows:
	Level 1 – Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
	Level 2 – Inputs (other than quoted market prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life.
	Level 3 – Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
	The following table sets forth the fair value of our financial assets and liabilities, allocated into Level 1, Level 2, and Level 3, that was measured on a recurring basis (in thousands):
		31-Mar-14
		Level 1		Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	25,344	$	—	$	—	$	25,344
	Corporate notes and commercial paper		—		176,478		—		176,478
	U.S. government agency securities		—		78,031		—		78,031
	Foreign currency forward contracts		—		245		—		245
	Total financial assets	$	25,344	$	254,754	$	—	$	280,098
		December 31, 2013
		Level 1		Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	57,296	$	—	$	—	$	57,296
	Corporate notes and commercial paper		—		182,472		—		182,472
	U.S. government agency securities		—		75,289		—		75,289
	Foreign currency forward contracts		—		372		—		372
	Total financial assets	$	57,296	$	258,133	$	—	$	315,429
	We estimate the fair values of our corporate notes and commercial paper and U.S government agency securities by taking into consideration valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income- and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; prepayment/default projections based on historical data; and other observable inputs.
	We have elected to use the income approach to value the foreign currency forward contracts, using observable Level 2 market expectations at the measurement date and standard valuation techniques to convert future amounts to a single present amount assuming that participants are motivated, but not compelled to transact. Level 2 inputs for the valuations are limited to quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for the asset or liability (specifically foreign currency spot and forward rates, and credit risk at commonly quoted intervals). Mid-market pricing is used as a practical expedient for fair value measurements. The fair value measurement of any asset or liability must reflect the non-performance risk of the entity and the counterparty to the transaction. Therefore, the impact of the counterparty’s creditworthiness, when in an asset position, and our creditworthiness, when in a liability position, has also been factored into the fair value measurement of the derivative instruments and did not have a material impact on the fair value of these derivative instruments. Both we and the counterparty are expected to continue to perform under the contractual terms of the instruments. There were no transfers between Level 1 and Level 2 during the periods presented.

Financial_Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2014
Financial Instruments	'
	4. Financial Instruments
	Cash equivalents, and investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):
		31-Mar-14									December 31, 2013
									Estimated									Estimated
				Unrealized		Unrealized			Fair				Unrealized		Unrealized			Fair
		Cost		Gain		(Loss)			Value		Cost		Gain		(Loss)			Value
	Money market funds	$	25,344	$	—	$	—		$	25,344	$	57,296	$	—	$	—		$	57,296
	Corporate notes and commercial paper		176,466		54		(42	)		176,478		182,426		62		(16	)		182,472
	U.S. government agency securities		78,016		29		(14	)		78,031		75,278		23		(12	)		75,289
		$	279,826	$	83	$	(56	)	$	279,853	$	315,000	$	85	$	(28	)	$	315,057
	Classified as:
	Cash equivalents								$	37,151								$	113,794
	Short-term investments									198,433									150,892
	Long-term investments									44,269									50,371
	Total cash equivalents and investments								$	279,853								$	315,057
	At March 31, 2014 and December 31, 2013, the remaining contractual maturities of available-for-sale securities were less than two years. There have been no significant realized gains or losses on available-for-sale securities for the periods presented.

Derivative_Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2014
Derivative Instruments	'
	5. Derivative Instruments
	We are exposed to foreign currency exchange rates related to our business operations. To reduce our risks related to these exposures, we utilize certain derivative instruments, namely foreign currency forward contracts. We do not use derivatives for speculative trading purposes.
	We enter into foreign currency forward contracts, none of which are designated as hedging transactions for accounting purposes, to reduce our exposure to foreign currency fluctuations of certain liabilities denominated in foreign currencies. These exposures are hedged on a quarterly basis. As of March 31, 2014 and December 31, 2013, we had foreign currency forward contracts with notional amounts of €4.9 million ($6.7 million based on the exchange rate as of March 31, 2014) and €7.7 million ($10.6 million based on the exchange rate as of December 31, 2013), respectively, that were not designated as hedges. As of March 31, 2014 and December 31, 2013, we recorded a derivative asset within prepaid expenses and other current assets of $245,000 and $372,000, respectively, related to these foreign currency forward contracts.
	We recorded an unrealized gain of $17,000 and an unrealized loss of $534,000 in interest and other income (expense), net on our condensed statements of operations related to these foreign currency forward contracts for the three months ended March 31, 2014 and 2013, respectively. During the three months ended March 31, 2014 and 2013, the Company settled foreign currency forward contracts and recognized a realized loss of $143,000 and $10,000, respectively, in interest and other income (expense), net.
	Our derivative financial instruments present certain market and counterparty risks. In general, the market risk related to these contracts is offset by corresponding gains and losses on the hedged transactions. The credit risk associated with these contracts is driven by changes in interest and currency exchange rates and, as a result, varies over time.

Balance_Sheet_Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2014
Balance Sheet Components	'
	6. Balance Sheet Components
	Accrued and other liabilities consist of the following (in thousands):
		March 31,		December 31,
		2014		2013
	Research and development related	$	14,136	$	16,110
	Legal and accounting fees		482		462
	Deferred rent		67		879
	Other		305		345
	Total accrued liabilities	$	14,990	$	17,796

Collaboration_and_License_Agre

Collaboration and License Agreements	3 Months Ended
	Mar. 31, 2014
Collaboration and License Agreements	'
	7. Collaboration and License Agreements
	Summary of Collaboration Related Revenue
	We have recognized revenue from our collaboration and license agreements as follows (in thousands):
		Three Months Ended March 31,
		2014		2013
	Bayer and Janssen	$	913	$	1,120
	BMS and Pfizer		442		1,988
	Daiichi Sankyo		955		—
	Lee's Pharmaceutical		62		—
	Total collaboration and license revenue	$	2,372	$	3,108
	Biogen Idec, Inc. (“Biogen Idec”)
	In October 2011, we entered into an exclusive, worldwide license and collaboration agreement with Biogen Idec, under which Portola and Biogen Idec were to jointly develop and commercialize selective, novel oral Syk inhibitors for the treatment of autoimmune and inflammatory diseases.
	In November 2012, we elected to exercise our option to convert the agreement to a fully out-licensed agreement. After election, we relinquished our right to share profits from sales of products related to selective Syk inhibitors, but are entitled to receive royalties from sales of these products by Biogen Idec. Following exercise of the option, we are no longer obligated to fund the program under the agreement. The out-licensed agreement now provides for future payments to us of up to approximately $370.0 million based on the occurrence of certain development and regulatory events. As all contingent consideration payments are based solely on the performance of Biogen Idec, the milestone method of accounting will not be applied to such amounts. Biogen Idec has elected to assume all future development work for Syk inhibitors, including the major indications, such as allergic asthma. This agreement will continue until either party terminates the agreement or until the expiration of Biogen Idec’s royalty obligations under the agreement. Biogen Idec may terminate the agreement without cause upon 120 days’ notice. In such event, we would regain all development rights and Biogen Idec would have no further payment obligations pursuant to the agreement.
	In April 2014, we entered into an amendment to the Biogen Idec license and collaboration agreement under which Biogen Idec released to us one of the Syk kinase inhibitors for use in topical ophthalmic indications. Per the terms of the amendment, the Company will be required to pay $15.0 million upon the completion of certain commercial milestones and pay royalties on sales of products approved for these Sky kinase inhibitors. There was no accounting effect resulting from this amendment.
	During the three months ended March 31, 2014 and 2013, we recorded a reduction in research and development expense of $70,000 and $330,000, respectively, owed by Biogen Idec to us under the cost-sharing terms of the agreement.
	Bristol-Myers Squibb Company (“BMS”) and Pfizer Inc. (“Pfizer”)
	In October 2012, we entered into a three-way agreement with BMS and Pfizer to include subjects dosed with apixaban, their jointly owned product candidate, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. The total consideration under this agreement of $6.0 million was recognized as revenue on a straight-line basis over the performance period through the fourth quarter of 2013.
	During the three months ended March 31, 2014 and 2013, we recognized $0 and $2.0 million in collaboration revenue under this agreement, respectively. The deferred revenue balance as of March 31, 2014 was $0.
	In January 2014, we entered into a three-way agreement with BMS and Pfizer to study the safety and efficacy of Andexanet alfa as a reversal agent to apixaban in our Phase 3 studies. We are responsible for the cost of conducting this clinical study. Pursuant to our agreement with BMS and Pfizer we are obligated to provide research, development and regulatory approval services and participate in the Joint Collaboration Committee (“JCC”) in exchange for an upfront fee of $13.0 million and up to $12.0 million of contingent payments due upon achievement of certain development and regulatory events. All consideration received and to be earned under this agreement is subject to a 50% refund contingent upon certain regulatory and/or clinical events.
	We concluded the January 2014 and October 2012 contracts should be accounted for as standalone agreements. We identified the following non-cancellable performance deliverables under the January 2014 agreement: 1) the obligation to provide research and development services, which includes manufacturing and supplying Andexanet alfa and providing various reports, and 2) the obligation to provide regulatory approval services, and 3) the obligation to participate on the JCC. We considered the provisions of the multiple-elements arrangement guidance in determining how to recognize the total agreement consideration. We determined that none of the deliverables have standalone value and all of these obligations will be delivered throughout the estimated period of performance and therefore are accounted for as a single unit of accounting. The non-contingent upfront consideration under this agreement of $6.5 million has been allocated to the single unit of accounting and is being recognized on a straight-line basis over the estimated period of performance through the first quarter of 2017. The contingent upfront consideration of $6.5 million will be recognized if and when the refundable nature of these amounts lapses based upon the achievement of specified regulatory and/or clinical events.
	The contingent milestone payments under the January 2014 agreement are not considered substantive because a portion may be refunded upon certain events. The non-contingent portion of the milestone payment will be recognized as collaboration revenue on a straight-line basis over the estimated period of performance through the first quarter of 2017. The contingent portion of the milestone payments will be recognized if and when the refundable nature of these amounts lapses based upon the achievement of specified regulatory and/or clinical events. None of these milestones had been earned or received at March 31, 2014.
	During the three months ended March 31, 2014 we recognized $442,000 in collaboration revenue. The deferred revenue balance as of March 31, 2014 was $12.6 million.
	Lee’s Pharmaceutical (HK) Ltd (“Lee’s”)
	In January 2013, we entered into an agreement with Lee’s to jointly expand our Phase 3 APEX Study of Betrixaban into China. Under the terms of the agreement, Lee’s provided us with an upfront and non-refundable fee of $700,000 and will reimburse our costs in connection with the expansion of the APEX study into China. Lee’s will lead this study and the regulatory interactions with China’s State Food and Drug Administration. We granted Lee’s an exclusive option to negotiate for the exclusive commercial rights to Betrixaban in China, which may be exercised by Lee’s for 60 days after it receives the primary data analysis report from the Phase 3 APEX study.
	We identified the following deliverables under the agreement with Lee’s: 1) the granting of an exclusive option to negotiate for the exclusive commercial rights to Betrixaban in China, 2) the obligation to manufacture and supply product in support of the APEX study in China, 3) the obligation to participate in a joint working group, and 4) the delivery of the primary data analysis report from the APEX study. We considered the provisions of the multiple-element arrangement guidance in determining how to recognize the total consideration of the agreement. We determined that none of the deliverables have standalone value and therefore are accounted for as a single unit of accounting with the upfront fee recognized as revenue on a straight-line basis over the estimated period of performance. Any reimbursements we may receive from Lee’s for the costs we incur in connection with this agreement are expected to be immaterial.
	During the three months ended March 31, 2014 and 2013, we recognized $62,000 and $0 of collaboration revenue under this agreement, respectively. The deferred revenue balance as of March 31, 2014 was $444,000.
	Aciex Therapeutics, Inc. (“Aciex”)
	In February 2013, we entered into a license and collaboration agreement with Aciex pursuant to which we granted Aciex an exclusive license to co-develop and co-commercialize Cerdulatinib (PRT2070) and certain related compounds for nonsystemic indications, such as the treatment and prevention of ophthalmological diseases by topical administration and allergic rhinitis by intranasal administration. In April 2014, this agreement was amended to release all rights for Cerdulatinib to Portola.  The collaboration is now focused on development of other related compounds for topical ophthalmic indications. Under the terms of this risk and cost sharing agreement, Portola and Aciex will each incur and report their own internal research and development costs. Further, third-party related development costs will be shared by Aciex and us 60% and 40%, respectively, until the end of the Phase 2 clinical study, and then equally afterwards. Also, we are entitled to receive either one-half of the profits, if any, generated by future sales of the products developed under the agreement, or royalty payments. Aciex has the primary responsibility for conducting the research and development activities under this agreement. We are obligated to provide assistance in accordance with the agreed upon development plan as well as participate on various committees. We can opt out of our obligation to share in the development costs at various points in time, the timing of which impacts future royalties we may receive based on product sales made by Aciex. All net costs we incur in connection with this agreement will be recognized as research and development expenses. During the three months ended March 31, 2014 and 2013 no such costs have been incurred related to this agreement.
	Bayer Pharma, AG (“Bayer”) and Janssen Pharmaceuticals, Inc. (“Janssen”)
	In February 2013, we entered into a three-way agreement with Bayer and Janssen to include subjects dosed with rivaroxaban, their Factor Xa inhibitor product, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. We are responsible for the cost of conducting this clinical study. Under the terms of the agreement, Bayer and Janssen have each provided us with an upfront and non-refundable fee of $2.5 million, for an aggregate fee of $5.0 million. The agreement also provides for additional non-refundable payments to us from Bayer and Janssen of $250,000 each for an aggregate of $500,000 following the delivery of the final written study report of our Phase 2 proof-of-concept studies of Andexanet alfa. Also, we are obligated to participate on a Joint Collaboration Committee (“JCC”) with Bayer and Janssen to oversee the collaboration activities under the agreement.
	We identified the following performance deliverables under the agreement: 1) the obligation to provide research and development services, which includes supplying Andexanet alfa and providing a final written report, and 2) the obligation to participate on a JCC. We considered the provisions of the multiple-element arrangement guidance in determining how to recognize the revenue associated with these two deliverables. We have accounted for the research and development services and our participation on the JCC as a single unit of accounting as neither deliverable has standalone value and both obligations will be delivered throughout the estimated period of performance. We originally estimated the period of performance to be through the fourth quarter of 2013. During 2013, we added more cohorts than originally planned as part of the original study design at the inception of our agreement and therefore adjusted our period of performance to be through the fourth quarter of 2014. The total consideration under this agreement is being recognized on a straight-line basis over the estimated performance period through the fourth quarter of 2014.
	During the three months ended March 31, 2014 and 2013, we recognized $401,000 and $1.1 million in collaboration revenue under this agreement, respectively. The deferred revenue balance as of March 31, 2014 was $722,000.
	In January 2014, we entered into a three-way agreement with Bayer and Janssen to study the safety and efficacy of Andexanet alfa as a reversal agent to their oral Factor Xa inhibitor, rivaroxaban, in our Phase 3 studies. We are responsible for the cost of conducting this clinical study. Pursuant to our agreement with Bayer and Janssen we are obligated to provide research, development and regulatory services and to participate in a JCC in exchange for an upfront nonrefundable fee of $10.0 million, up to three contingent payments totaling $7.0 million which are payable upon achievement of certain events associated with scaling up our manufacturing process to support a commercial launch, and up to three payments totaling $8.0 million which are payable upon initiation of our Phase 3 study and regulatory approval of Andexanet alfa as a reversal agent to rivaroxaban by the FDA and European Medicines Agency (“EMA”).
	We identified the following non-cancellable performance deliverables under the agreement: 1) the obligation to provide research and development services, which include manufacturing and supplying Andexanet alfa and providing various reports, and 2) the obligation to provide regulatory approval services, and 3) the obligation to participate on the JCC. We considered the provisions of the multiple-element arrangement guidance in determining how to recognize the total consideration of the agreement.  We determined that none of the deliverables have standalone value, all of these obligations will be delivered throughout the estimated period of performance and therefore are accounted for as a single unit of accounting. The total upfront consideration under this agreement is being recognized as revenue on a straight-line basis over the estimated performance period through the first quarter of 2017.
	We have determined all but one of the future contingent payments meet the definition of a milestone and that such milestones are substantive in that the consideration is reasonable relative to all of the deliverables and payment terms within the agreement and commensurate with our performance to achieve the milestone after commencement of the agreement. Accordingly, revenue for the achievement of these milestones will be recognized in the period when the milestone is achieved and collectability is reasonably assured. As of March 31, 2014, no amounts had been recognized as collaboration revenue for any of these milestones. Amounts for the continent payment not considered to be a substantive milestone will be deferred when received and recognized as collaboration revenue on a straight-line basis over the estimated performance period through the first quarter of 2017.
	During the three months ended March 31, 2014 we recognized $511,000  in collaboration revenue under this agreement. The deferred revenue balance as of March 31, 2014 was $9.5 million.
	Daiichi Sankyo, Inc. (“Daiichi Sankyo”)
	In June 2013, we entered into an agreement with Daiichi Sankyo to include subjects dosed with edoxaban, their Factor Xa inhibitor product, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. We are responsible for the cost of conducting this clinical study. Under the terms of the agreement, Daiichi Sankyo provided us with an upfront fee of $6.0 million, $3.0 million of which was subject to refund if Daiichi Sankyo decided to terminate the agreement. We are obligated to participate on a JCC with Daiichi Sankyo to oversee the collaboration activities under the agreement.
	We identified the following performance deliverables under the agreement: 1) the obligation to provide research and development services, which includes supplying Andexanet alfa and providing a final written report, and 2) the obligation to participate on the JCC.
	We considered the provisions of the multiple-element arrangement guidance in determining how to recognize the revenue associated with these two deliverables. We have accounted for the research and development services and our participation on the JCC as a single unit of accounting as neither deliverable has standalone value and both obligations will be delivered throughout the estimated period of performance. We originally estimated the non-contingent consideration under this agreement of $3.0 million would be recorded as revenue on a straight-line basis over the estimated non-contingent performance period through the second quarter of 2014. In December 2013, the JCC agreed to forego certain preclinical studies that were planned in the original study design at the inception of the agreement. As a result of this change, we updated our period of performance to be through the first quarter of 2014.
	The total non-contingent consideration under this agreement of $3.0 million was fully recognized as revenue on a straight-line basis over the estimated non-contingent performance period through the first quarter of 2014. The recognition of contingent consideration under this agreement of $3.0 million commenced upon resolution of the contingency in the first quarter of 2014 and is being recognized over the remaining estimated period of performance through the first quarter of 2015.
	During the three months ended March 31, 2014 and 2013, we recognized $955,000, and $0 in collaboration revenue associated with the contingent and non-contingent elements of the arrangement, respectively. The deferred revenue balance as of March 31, 2014 was $2.6 million.

Stock_Based_Compensation

Stock Based Compensation	3 Months Ended
	Mar. 31, 2014
Stock Based Compensation	'
	8. Stock Based Compensation
	In January 2013, our Board of Directors adopted our 2013 Equity Incentive Plan, or the 2013 Plan, which became effective upon of the closing of our IPO in May 2013. On January 1, 2014, the number of shares available for issuance under the 2013 Plan automatically increased by a number of shares equal to 5% of the total common stock outstanding at December 31, 2013. As of March 31, 2014 there were 6,949,108 shares reserved under the 2013 Plan for the issuance of awards.
	The following table summarizes option activity under our 2013 Equity Incentive Plan and related information during the three months ended March 31, 2014:
					Shares
					Subject to			Weighted-
		Shares Available			Outstanding			Average Exercise
		for Grant			Options			Price Per Share
	Balance at December 31, 2013		81,948			3,708,773		$	9.43
	Options authorized		2,045,785			—			—
	Options granted		(671,613	)		671,613			25.14
	Options exercised		—			(157,833	)		6.39
	Options canceled		19,732			(19,732	)		17.76
	Balance at March 31, 2014		1,475,852			4,202,821		$	12.02
	The estimated grant date fair values of the employee stock options were calculated using the Black Scholes valuation model, based on the following assumptions:
		Three Months Ended March 31,
		2014			2013
	Risk-free interest rate		1.88	%		1.1	%
	Expected life	6.0 years			6.0 years
	Expected Volatility		79	%		72	%
	Dividend yield		—			—

Net_Loss_per_Share_Attributabl

Net Loss per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2014
Net Loss per Share Attributable to Common Stockholders	'
	9. Net Loss per Share Attributable to Common Stockholders
	Basic net loss per share attributable to common stockholders has been computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share attributable to common stockholders is calculated by dividing net loss by the weighted average number of shares of common stock and potential dilutive securities outstanding during the period.
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Three Months Ended March 31,
		2014		2013
	Convertible preferred stock		—		24,026,797
	Stock options to purchase common stock		4,202,821		1,653,298
	Preferred stock warrants		—		81,075
	Common stock warrants		13,873		1,500

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”), and following the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, that are necessary for a fair statement of the Company’s financial information. The results of operations for the three months ended March 31, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014. The condensed balance sheet as of December 31, 2013 has been derived from audited financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements.
	The accompanying condensed financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K filed March 3, 2014 with the SEC.
Use of Estimates	'
	Use of Estimates
	The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the condensed financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, clinical trial accruals, fair value of assets and liabilities, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results may differ from those estimates.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	Cash and cash equivalents consist of cash and other highly liquid investments with original maturities of three months or less from the date of purchase.
Investments	'
	Investments
	All investments have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and reevaluates such designation as of each balance sheet date. Unrealized gains and losses are excluded from earnings and were reported as a component of accumulated comprehensive income. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in interest and other income (expense), net. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest and other income (expense), net.
Customer Concentration	'
	Customer Concentration
	Customers whose collaborative research and development revenue accounted for 10% or more of total revenues were as follows:
		Three Months Ended
		March 31,
		2014			2013
	Bristol-Myers Squibb Company and Pfizer Inc.		19	%		64	%
	Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		38	%		36	%
	Daiichi Sankyo, Inc		40	%		—
Revenue Recognition	'
	Revenue Recognition
	We generate revenue from collaboration and license agreements for the development and commercialization of our products. Collaboration and license agreements may include non-refundable or partially refundable upfront license fees, partial or complete reimbursement of research and development costs, contingent consideration payments based on the achievement of defined collaboration objectives and royalties on sales of commercialized products. Our performance obligations under our collaborations include the transfer of intellectual property rights (licenses), obligations to provide research and development services and related materials, obligations to manufacture and supply of Andexanet alfa and obligations to participate on certain development and/or commercialization committees with the collaborators.
	Payments that are contingent upon achievement of a substantive milestone are recognized in their entirety in the period in which the milestone is achieved. Milestones are defined as an event that can only be achieved based on our performance and there is substantive uncertainty about whether the event will be achieved at the inception of the arrangement. Events that are contingent only on the passage of time or only on counterparty performance are not considered milestones subject to this guidance. Further, the amounts received must relate solely to prior performance, be reasonable relative to all of the deliverables and payment terms within the agreement and commensurate with our performance to achieve the milestone after commencement of the agreement. Payments contingent upon achievement of events that are not considered substantive milestones are allocated to the respective arrangements unit of accounting when received and recognized as revenue based on the revenue recognition policy for that unit of accounting.
	Amounts from sales of licenses are recognized as revenue, as licensing of intellectual property is one of our principal or major ongoing activities. Amounts received as funding of research and development activities are recognized as revenue if the collaboration arrangement involves the sale of our research or development services at amounts that exceed our cost. However, such funding is recognized as a reduction in research and development expense when we engage in a research and development project jointly with another entity, with both entities participating in project activities and sharing costs and potential benefits of the arrangement.
	Amounts related to research and development funding are recognized as the related services or activities are performed, in accordance with the contract terms. Payments may be made to or by us based on the number of full-time equivalent researchers assigned to the collaboration project and the related research and development expenses incurred.
Foreign Currency Transactions and Hedging	'
	Foreign Currency Transactions and Hedging
	We have transactions denominated in foreign currencies, primarily the Euro, and, as a result, are exposed to changes in foreign currency exchange rates. We manage a portion of these cash flow exposures through the purchase of Euros and the use of foreign currency forward contracts. Our foreign currency forward contracts are not designated as hedges for accounting purposes. Gains or losses on foreign currency forward contracts are intended to offset gains or losses on the underlying net exposures in an effort to reduce the earnings and cash flow volatility resulting from fluctuating foreign currency exchange rates. Foreign currencies and our foreign currency forward contracts are marked to market at the end of each period and recorded as gains and losses in the condensed statements of operations.
	Our foreign exchange forward contracts expose us to credit risk to the extent that the counterparty, a major financial institution, is unable to meet the terms of the agreement. Our management does not expect material losses as a result of defaults by the counterparty.
Net Loss per Share Attributable to Common Stockholders	'
	Net Loss per Share Attributable to Common Stockholders
	Basic and diluted net loss per share attributable to common stockholders is calculated in conformity with the two-class method required for companies with participating securities. Under the two-class method, in periods when we have net income, basic net income attributable to common stockholders is determined by allocating undistributed earnings, calculated as net income less current period convertible preferred stock noncumulative dividends, between the common stock and the convertible preferred stock. In computing diluted net income attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods when we have incurred a net loss, convertible preferred stock, options and warrants to purchase common stock and convertible preferred stock warrants are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2014
Revenue Accounted for 10% or More of Total Revenues	'
	Customers whose collaborative research and development revenue accounted for 10% or more of total revenues were as follows:
		Three Months Ended
		March 31,
		2014			2013
	Bristol-Myers Squibb Company and Pfizer Inc.		19	%		64	%
	Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		38	%		36	%
	Daiichi Sankyo, Inc		40	%		—

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Summary of Financial Assets, and Liabilities, Allocated into Level 1, Level 2, and Level 3 Measured on Recurring Basis	'
	The following table sets forth the fair value of our financial assets and liabilities, allocated into Level 1, Level 2, and Level 3, that was measured on a recurring basis (in thousands):
		31-Mar-14
		Level 1		Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	25,344	$	—	$	—	$	25,344
	Corporate notes and commercial paper		—		176,478		—		176,478
	U.S. government agency securities		—		78,031		—		78,031
	Foreign currency forward contracts		—		245		—		245
	Total financial assets	$	25,344	$	254,754	$	—	$	280,098
		December 31, 2013
		Level 1		Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	57,296	$	—	$	—	$	57,296
	Corporate notes and commercial paper		—		182,472		—		182,472
	U.S. government agency securities		—		75,289		—		75,289
	Foreign currency forward contracts		—		372		—		372
	Total financial assets	$	57,296	$	258,133	$	—	$	315,429

Financial_Instruments_Tables

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2014
Cash Equivalents and Investments Classified as Available-for-sale Securities	'
	Cash equivalents, and investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):
		31-Mar-14									December 31, 2013
									Estimated									Estimated
				Unrealized		Unrealized			Fair				Unrealized		Unrealized			Fair
		Cost		Gain		(Loss)			Value		Cost		Gain		(Loss)			Value
	Money market funds	$	25,344	$	—	$	—		$	25,344	$	57,296	$	—	$	—		$	57,296
	Corporate notes and commercial paper		176,466		54		(42	)		176,478		182,426		62		(16	)		182,472
	U.S. government agency securities		78,016		29		(14	)		78,031		75,278		23		(12	)		75,289
		$	279,826	$	83	$	(56	)	$	279,853	$	315,000	$	85	$	(28	)	$	315,057
	Classified as:
	Cash equivalents								$	37,151								$	113,794
	Short-term investments									198,433									150,892
	Long-term investments									44,269									50,371
	Total cash equivalents and investments								$	279,853								$	315,057

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2014
Accrued Expenses	'
	Accrued and other liabilities consist of the following (in thousands):
		March 31,		December 31,
		2014		2013
	Research and development related	$	14,136	$	16,110
	Legal and accounting fees		482		462
	Deferred rent		67		879
	Other		305		345
	Total accrued liabilities	$	14,990	$	17,796

Collaboration_and_License_Agre1

Collaboration and License Agreements (Tables)	3 Months Ended
	Mar. 31, 2014
Summary of Revenue from Collaboration and License Agreements	'
	We have recognized revenue from our collaboration and license agreements as follows (in thousands):
		Three Months Ended March 31,
		2014		2013
	Bayer and Janssen	$	913	$	1,120
	BMS and Pfizer		442		1,988
	Daiichi Sankyo		955		—
	Lee's Pharmaceutical		62		—
	Total collaboration and license revenue	$	2,372	$	3,108

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Summary of Option Activities	'
	The following table summarizes option activity under our 2013 Equity Incentive Plan and related information during the three months ended March 31, 2014:
					Shares
					Subject to			Weighted-
		Shares Available			Outstanding			Average Exercise
		for Grant			Options			Price Per Share
	Balance at December 31, 2013		81,948			3,708,773		$	9.43
	Options authorized		2,045,785			—			—
	Options granted		(671,613	)		671,613			25.14
	Options exercised		—			(157,833	)		6.39
	Options canceled		19,732			(19,732	)		17.76
	Balance at March 31, 2014		1,475,852			4,202,821		$	12.02
Fair Values of Employee Stock Options	'
	The estimated grant date fair values of the employee stock options were calculated using the Black Scholes valuation model, based on the following assumptions:
		Three Months Ended March 31,
		2014			2013
	Risk-free interest rate		1.88	%		1.1	%
	Expected life	6.0 years			6.0 years
	Expected Volatility		79	%		72	%
	Dividend yield		—			—
Classification of Stock-Based Compensation Expense	'
		Three Months Ended March 31,
		2014			2013
	Research and development	$	1,066		$	336
	General and administrative		1,236			377
	Total stock-based compensation	$	2,302		$	713

Net_Loss_per_Share_Attributabl1

Net Loss per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2014
Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss	'
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Three Months Ended March 31,
		2014		2013
	Convertible preferred stock		—		24,026,797
	Stock options to purchase common stock		4,202,821		1,653,298
	Preferred stock warrants		—		81,075
	Common stock warrants		13,873		1,500

Organization_Additional_Inform

Organization - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
	Segment
Organization And Nature Of Business [Line Items]	'
Number of operating segment	1

Revenue_Accounted_for_10_or_Mo

Revenue Accounted for 10% or More of Total Revenues (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	'	'
Concentration Risk [Line Items]	'	'
Percentage of major customers revenue accounted for 10% or more of total revenues	19.00%	64.00%
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	'	'
Concentration Risk [Line Items]	'	'
Percentage of major customers revenue accounted for 10% or more of total revenues	38.00%	36.00%
Daiichi Sankyo, Inc ("Daiichi")	'	'
Concentration Risk [Line Items]	'	'
Percentage of major customers revenue accounted for 10% or more of total revenues	40.00%	'

Summary_of_Financial_Assets_an

Summary of Financial Assets, and Liabilities, Allocated into Level 1, Level 2, and Level 3 Measured on Recurring Basis (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Assets:	'	'
Total financial assets	$280,098	$315,429
Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Total financial assets	25,344	57,296
Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Total financial assets	254,754	258,133
Money market funds	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	25,344	57,296
Money market funds | Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	25,344	57,296
Corporate notes and commercial paper	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	176,478	182,472
Corporate notes and commercial paper | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	176,478	182,472
U.S. government agency securities	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	78,031	75,289
U.S. government agency securities | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	78,031	75,289
Foreign currency forward contracts	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	245	372
Foreign currency forward contracts | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	$245	$372

Cash_Equivalents_and_Investmen

Cash Equivalents and Investments Classified as Available-for-sale Securities (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]	'	'
Cost	$279,826	$315,000
Unrealized Gain	83	85
Unrealized (Loss)	-56	-28
Estimated Fair Value	279,853	315,057
Money market funds	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	25,344	57,296
Estimated Fair Value	25,344	57,296
Corporate notes and commercial paper	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	176,466	182,426
Unrealized Gain	54	62
Unrealized (Loss)	-42	-16
Estimated Fair Value	176,478	182,472
U.S. government agency securities	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	78,016	75,278
Unrealized Gain	29	23
Unrealized (Loss)	-14	-12
Estimated Fair Value	78,031	75,289
Cash equivalents	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Estimated Fair Value	37,151	113,794
Short-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Estimated Fair Value	198,433	150,892
Long-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Estimated Fair Value	$44,269	$50,371

Financial_Instruments_Addition

Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]	'	'
Available For Sale Securities Contractual Maturity	'2 years	'2 years
Available-for-sale Securities, Gross Realized Gain (Loss)	$0	$0

Derivative_Instruments_Additio

Derivative Instruments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013
	USD ($)	USD ($)	EUR (€)	USD ($)	EUR (€)	Prepaid Expenses and Other Current Assets	Prepaid Expenses and Other Current Assets
						USD ($)	USD ($)
Derivatives Fair Value [Line Items]	'	'	'	'	'	'	'
Foreign currency forward contracts, notional amount	$6,700,000	'	€ 4,900,000	$10,600,000	€ 7,700,000	'	'
Derivative assets	'	'	'	'	'	245,000	372,000
Foreign currency forward contracts unrealized gain (loss)	17,000	-534,000	'	'	'	'	'
Foreign currency forward contracts recognized realized gain (loss)	($143,000)	($10,000)	'	'	'	'	'

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]	'	'
Research and development related	$14,136	$16,110
Legal and accounting fees	482	462
Deferred rent	67	879
Other	305	345
Total accrued liabilities	$14,990	$17,796

Summary_of_Revenue_from_Collab

Summary of Revenue from Collaboration and License Agreements (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'
Collaboration and license revenue	$2,372	$3,108
Licensing Agreements | Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'
Collaboration and license revenue	913	1,120
Licensing Agreements | Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'
Collaboration and license revenue	442	1,988
Licensing Agreements | Daiichi Sankyo, Inc ("Daiichi")	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'
Collaboration and license revenue	955	'
Licensing Agreements | Lee's Pharmaceutical (HK) Ltd (“Lee's”)	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'
Collaboration and license revenue	$62	'

Collaboration_and_License_Agre2

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

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

Nov. 30, 2012

Mar. 31, 2014

Mar. 31, 2013

Apr. 30, 2014

Jan. 31, 2014

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Jan. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Feb. 01, 2013

Feb. 01, 2013

Jan. 31, 2014

Feb. 01, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2013

Jun. 30, 2013

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Biogen Idec

Biogen Idec

Biogen Idec

Biogen Idec

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")

Lee's Pharmaceutical (HK) Ltd (“Lee's”)

Lee's Pharmaceutical (HK) Ltd (“Lee's”)

Lee's Pharmaceutical (HK) Ltd (“Lee's”)

Lee's Pharmaceutical (HK) Ltd (“Lee's”)

Aciex Therapeutics, Inc. (“Aciex”)

Bayer Pharma AG

Janssen Pharmaceuticals, Inc.

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")

Daiichi Sankyo, Inc ("Daiichi")

Daiichi Sankyo, Inc ("Daiichi")

Daiichi Sankyo, Inc ("Daiichi")

Daiichi Sankyo, Inc ("Daiichi")

Daiichi Sankyo, Inc ("Daiichi")

PORTOLA PHARMACEUTICALS INC

Subsequent Event

October 2012 Agreement

October 2012 Agreement

October 2012 Agreement

January 2014 Agreement

January 2014 Agreement

Collaborative Arrangement

Collaborative Arrangement

January 2014 Agreement

January 2014 Agreement

February 2013 Agreement

February 2013 Agreement

February 2013 Agreement

Collaborative Arrangement

Collaborative Arrangement

Second Quarter

First Quarter

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

Research And Development Arrangement Contract To Perform For Others [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

License fee receivable upon occurrence of certain development and regulatory events

$370,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notice period for agreement termination

'120 days

'

'

'

'

'

'

'

'

'

'

'

'60 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments Upon the Completion of Certain Commercial Milestones

'

'

'

15,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reduction in research and development expense

'

70,000

330,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred revenue

'

'

'

'

'

'

6,000,000

0

'

'

12,600,000

'

'

444,000

'

'

'

'

'

'

'

9,500,000

'

722,000

'

'

'

2,600,000

'

'

'

'

Collaboration revenue recognized

'

'

'

'

'

'

'

'

0

2,000,000

'

442,000

'

'

62,000

0

'

'

'

'

'

'

511,000

'

401,000

1,100,000

'

955,000

0

'

'

'

Upfront fee

'

'

'

'

13,000,000

'

'

'

'

'

'

'

700,000

'

'

'

'

2,500,000

2,500,000

10,000,000

5,000,000

'

'

'

'

'

'

'

'

'

'

'

Milestone Payments of Development and Regulatory Event

'

'

'

'

12,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of consideration received under agreement

'

'

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Non-contingent consideration being recognized as revenue over estimated period of performance

'

'

'

'

'

6,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000,000

3,000,000

'

Contingent consideration to be recognized after resolution of contingency

'

'

'

'

'

6,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000,000

'

Development costs, percent

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40.00%

Additional non-refundable fee

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

250,000

250,000

'

500,000

'

'

'

'

'

'

'

'

'

'

'

Contingent payment payable upon achievement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Collaborative arrangement upfront payment to be received

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,000,000

'

'

'

'

'

Upfront fee subject to refund

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3,000,000

'

'

'

'

'

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]	'
Percentage increase in number of common stock outstanding	5.00%
Number of common stock shares reserved for issuance under the 2013 Equity Incentive Plan	6,949,108

Summary_of_Stock_Option_Activi

Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Shares Available for Grant	'
Beginning balance	81,948
Options authorized	2,045,785
Options granted	-671,613
Options canceled	19,732
Ending balance	1,475,852
Shares Subject to Outstanding Options	'
Beginning balance	3,708,773
Options granted	671,613
Options exercised	-157,833
Options canceled	-19,732
Ending balance	4,202,821
Weighted-Average Exercise Price Per Share	'
Beginning balance	$9.43
Options granted	$25.14
Options exercised	$6.39
Options canceled	$17.76
Ending balance	$12.02

Fair_Values_of_Employee_Stock_

Fair Values of Employee Stock Options (Detail) (Stock Option)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock Option	'	'
Share Based Compensation Arrangement Assumptions Used To Estimate Fair Values Of Share Options Granted [Line Items]	'	'
Risk-free interest rate	1.88%	1.10%
Expected life	'6 years	'6 years
Expected Volatility	79.00%	72.00%
Dividend yield	'	'

Classification_of_StockBased_C

Classification of Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'
Stock-based compensation	$2,302	$713
Research and Development Expense	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'
Stock-based compensation	1,066	336
General and Administrative Expense	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'
Stock-based compensation	$1,236	$377

Outstanding_Shares_of_Common_S

Outstanding Shares of Common Stock Excluded from Computation of Diluted Net Income (Loss) per Share (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Convertible Preferred Stock	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computation of diluted net loss per share	'	24,026,797
Stock options to purchase common stock	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computation of diluted net loss per share	4,202,821	1,653,298
Preferred stock warrants	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computation of diluted net loss per share	'	81,075
Common stock warrants	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computation of diluted net loss per share	13,873	1,500