Portola Pharmaceuticals (PTLA) 10-K 3 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Feb. 28, 2014	Jun. 28, 2013
Document Information [Line Items]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'PTLA	'	'
Entity Registrant Name	'PORTOLA PHARMACEUTICALS INC	'	'
Entity Central Index Key	'0001269021	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Non-accelerated Filer	'	'
Entity Public Float	'	'	$322.40
Entity Common Stock, Shares Outstanding	'	41,029,043	'

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$117,773	$53,613
Short-term investments	150,892	77,656
Receivables from collaborations	309	662
Prepaid expenses and other current assets	3,733	2,982
Total current assets	272,707	134,913
Property and equipment, net	2,600	2,861
Long-term investments	50,371	6,115
Other assets	53	2,112
Total assets	325,731	146,001
Current liabilities:	'	'
Accounts payable	3,232	4,840
Accrued compensation and employee benefits	2,569	1,860
Accrued and other liabilities	17,796	7,399
Deferred revenue, current portion	1,958	4,042
Convertible preferred stock warrant liability	'	683
Total current liabilities	25,555	18,824
Deferred revenue, long-term	3,253	'
Other long-term liabilities	588	1,466
Total liabilities	29,396	20,290
Commitments and contingencies (Note 11)	'	'
Convertible preferred stock, $0.001 par value, 0 and 243,258,300 shares authorized at December 31, 2013 and 2012; 0 and 24,026,797 shares issued and outstanding at December 31, 2013 and 2012; redemption value of $317,280 at December 31, 2012	'	317,280
Stockholders’ equity (deficit):	'	'
Preferred stock, $0.001 par value, 5,000,000 shares authorized at December 31, 2013; 0 shares issued and outstanding at December 31, 2013; 0 authorized, issued and outstanding at December 31, 2012	'	'
Common stock, $0.001 par value, 100,000,000 and 300,000,000 shares authorized at December 31, 2013 and 2012; 40,915,130 and 1,385,508 shares issued and outstanding at December 31, 2013 and 2012	41	1
Additional paid-in capital	581,911	10,717
Accumulated deficit	-285,672	-202,320
Accumulated other comprehensive income	55	33
Total stockholders’ equity (deficit)	296,335	-191,569
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$325,731	$146,001

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	0	243,258,300
Convertible preferred stock, shares issued	0	24,026,797
Convertible preferred stock, shares outstanding	0	24,026,797
Convertible preferred stock, redemption value	'	$317,280
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	0
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	300,000,000
Common stock, shares issued	40,915,130	1,385,508
Common stock, shares outstanding	40,915,130	1,385,508

Statements_of_Operations

Statements of Operations (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Collaboration and license revenue	$10,531	$72,042	$78,029
Operating expenses:	'	'	'
Research and development	79,286	49,717	46,089
General and administrative	15,423	11,469	12,071
Total operating expenses	94,709	61,186	58,160
Income (loss) from operations	-84,178	10,856	19,869
Interest and other income, net	826	510	136
Interest expense	'	'	-21
Net income (loss)	-83,352	11,366	19,984
Net income (loss) attributable to common stockholders:	'	'	'
Basic	-83,352	'	79
Diluted	($83,352)	'	$127
Net income (loss) per share attributable to common stockholders:	'	'	'
Basic	($3.65)	'	$0.06
Diluted	($3.65)	'	$0.06
Shares used to compute net income (loss) per share attributable to common stockholders:	'	'	'
Basic	22,842,443	1,350,939	1,249,778
Diluted	22,842,443	2,048,867	2,089,206

Condensed_Statements_of_Compre

Condensed Statements of Comprehensive Income (Loss) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income (loss)	($83,352)	$11,366	$19,984
Other comprehensive income:	'	'	'
Unrealized gain on available-for-sale securities, net of tax	22	34	3
Total comprehensive income (loss)	($83,330)	$11,400	$19,987

Statements_of_Convertible_Pref

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $)

Total

Series D Preferred Stock

Series 1 Preferred Stock

IPO

Follow-on Offering

Convertible Preferred Stock

Convertible Preferred Stock

Convertible Preferred Stock

Common Stock

Common Stock

Common Stock

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Retained Earnings

Accumulated Other Comprehensive Income (Loss)

In Thousands, except Share data

Series D Preferred Stock

Series 1 Preferred Stock

IPO

Follow-on Offering

Series D Preferred Stock

Series 1 Preferred Stock

IPO

Follow-on Offering

Balance at beginning of year at Dec. 31, 2010

($228,407)

'

'

'

'

$220,374

'

'

$1

'

'

$5,266

'

'

'

'

($233,670)

($4)

Balance at beginning of year (in shares) at Dec. 31, 2010

'

'

'

'

'

17,103,729

'

'

1,224,782

'

'

'

'

'

'

'

'

'

Exercise of employee stock options for cash (in shares)

'

'

'

'

'

'

'

'

51,336

'

'

'

'

'

'

'

'

'

Exercise of employee stock options for cash

149

'

'

'

'

'

'

'

'

'

'

149

'

'

'

'

'

'

Lapse of repurchase rights related to common shares issued pursuant to early exercises (in shares)

'

'

'

'

'

'

'

'

3.614

'

'

'

'

'

'

'

'

'

Lapse of repurchase rights related to common shares issued pursuant to early exercises

19

'

'

'

'

'

'

'

'

'

'

19

'

'

'

'

'

'

Issuance of stock (in shares)

'

'

'

'

'

'

6,287,026

636,042

'

'

'

'

'

'

'

'

'

'

Issuance of stock

'

-115

-91

'

'

'

88,962

7,944

'

'

'

'

-115

-91

'

'

'

'

Employee stock-based compensation expense

2,288

'

'

'

'

'

'

'

'

'

'

2,288

'

'

'

'

'

'

Compensation expense relating to stock options granted to consultants

65

'

'

'

'

'

'

'

'

'

'

65

'

'

'

'

'

'

Unrealized gain on available-for-sale securities, net of tax

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3

Net income (loss)

19,984

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

19,984

'

Balance at end of the year at Dec. 31, 2011

-206,105

'

'

'

'

317,280

'

'

1

'

'

7,581

'

'

'

'

-213,686

-1

Balance at end of the year (in shares) at Dec. 31, 2011

'

'

'

'

'

24,026,797

'

'

1,279,732

'

'

'

'

'

'

'

'

'

Exercise of employee stock options for cash (in shares)

'

'

'

'

'

'

'

'

104,417

'

'

'

'

'

'

'

'

'

Exercise of employee stock options for cash

317

'

'

'

'

'

'

'

'

'

'

317

'

'

'

'

'

'

Lapse of repurchase rights related to common shares issued pursuant to early exercises (in shares)

'

'

'

'

'

'

'

'

1,359

'

'

'

'

'

'

'

'

'

Lapse of repurchase rights related to common shares issued pursuant to early exercises

10

'

'

'

'

'

'

'

'

'

'

10

'

'

'

'

'

'

Employee stock-based compensation expense

2,665

'

'

'

'

'

'

'

'

'

'

2,665

'

'

'

'

'

'

Compensation expense relating to stock options granted to consultants

144

'

'

'

'

'

'

'

'

'

'

144

'

'

'

'

'

'

Unrealized gain on available-for-sale securities, net of tax

34

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34

Net income (loss)

11,366

'

'

'

'

'

'

'

'

'

'

10,717

'

'

'

'

11,366

'

Balance at end of the year at Dec. 31, 2012

-191,569

'

'

'

'

317,280

'

'

1

'

'

'

'

'

'

'

-202,320

33

Balance at end of the year (in shares) at Dec. 31, 2012

'

'

'

'

'

24,026,797

'

'

1,385,508

'

'

'

'

'

'

'

'

'

Exercise of employee stock options for cash (in shares)

403,468

'

'

'

'

'

'

'

403,468

'

'

'

'

'

'

'

'

'

Exercise of employee stock options for cash

2,529

'

'

'

'

'

'

'

'

'

'

2,529

'

'

'

'

'

'

Lapse of repurchase rights related to common shares issued pursuant to early exercises (in shares)

'

'

'

'

'

'

'

'

500

'

'

'

'

'

'

'

'

'

Lapse of repurchase rights related to common shares issued pursuant to early exercises

4

'

'

'

'

'

'

'

'

'

'

4

'

'

'

'

'

'

Issuance of stock (in shares)

'

'

'

'

'

'

'

'

'

9,686,171

5,412,686

'

'

'

'

'

'

'

Issuance of stock

'

'

'

125,872

119,975

'

'

'

'

11

5

'

'

'

125,861

119,970

'

'

Employee stock-based compensation expense

4,140

'

'

'

'

'

'

'

'

'

'

4,140

'

'

'

'

'

'

Compensation expense relating to stock options granted to consultants

775

'

'

'

'

'

'

'

'

'

'

775

'

'

'

'

'

'

Unrealized gain on available-for-sale securities, net of tax

22

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

22

Net income (loss)

-83,352

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-83,352

'

Conversion of preferred stock warrants to common stock warrants

659

'

'

'

'

'

'

'

'

'

'

659

'

'

'

'

'

'

Conversion of preferred stock to common stock (in shares)

'

'

'

'

'

-24,026,797

'

'

24,026,797

'

'

'

'

'

'

'

'

'

Conversion of preferred stock to common stock

317,280

'

'

'

'

-317,280

'

'

24

'

'

317,256

'

'

'

'

'

'

Balance at end of the year at Dec. 31, 2013

$296,335

'

'

'

'

'

'

'

$41

'

'

$581,911

'

'

'

'

($285,672)

$55

Balance at end of the year (in shares) at Dec. 31, 2013

'

'

'

'

'

0

'

'

40,915,130

'

'

'

'

'

'

'

'

'

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities	'	'	'
Net income (loss)	($83,352)	$11,366	$19,984
Adjustments to reconcile net income (loss) to cash used in operating activities:	'	'	'
Depreciation and amortization	1,359	1,389	1,382
Noncash interest expense	'	'	7
Amortization of premium on investment securities	2,333	1,469	751
Stock-based compensation expense	4,974	2,809	2,353
Revaluation of convertible preferred stock warrant liability	-24	-83	-23
Unrealized gain on foreign currency forward contracts	-261	-51	'
Changes in operating assets and liabilities:	'	'	'
Receivables from collaborations	353	293	-955
Prepaid expenses and other current assets	-469	-2,481	1,615
Other assets	396	-2,091	'
Accounts payable	-1,773	2,017	1,437
Accrued compensation and employee benefits	650	-980	117
Accrued and other liabilities	11,908	3,375	-171
Deferred revenue	1,169	-65,426	-35,387
Other long-term liabilities	-878	-831	45
Accrued income taxes	'	'	-2,476
Net cash used in operating activities	-63,615	-49,225	-11,321
Investing activities	'	'	'
Decrease in restricted cash	'	'	6,000
Purchases of property and equipment	-933	-362	-1,477
Purchases of investments	-219,813	-144,644	-33,805
Proceeds from sales of investments	8,009	36,517	2,163
Proceeds from maturities of investments	92,001	40,687	59,829
Net cash (used in) provided by investing activities	-120,736	-67,802	32,710
Financing activities	'	'	'
Proceeds from public offering of common stock, net of underwriters discount	251,865	'	'
Payment of public offering costs	-5,883	'	'
Proceeds from issuance of common stock, including early exercise of stock options	2,529	317	167
Repurchase of unvested common stock	'	'	-51
Proceeds from issuance of convertible preferred stock, net of issuance costs	'	'	96,700
Repayment of debt	'	'	-2,598
Net cash provided by financing activities	248,511	317	94,218
Net increase (decrease) in cash and cash equivalents	64,160	-116,710	115,607
Cash and cash equivalents at beginning of year	53,613	170,323	54,716
Cash and cash equivalents at end of year	117,773	53,613	170,323
Supplemental disclosure of cash flow information	'	'	'
Interest paid	'	'	14
Income taxes paid	'	57	2,476
Noncash investing activities	'	'	'
Net change in accounts payable related to purchase of property and equipment	$165	'	($362)

Organization

Organization	12 Months Ended
	Dec. 31, 2013
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 novel therapeutics in the areas of thrombosis, other hematologic disorders and inflammation for patients who currently have limited or no approved treatment options. 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 the area of thrombosis, or blood clots. 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, formerly PRT4445, is a recombinant protein designed to reverse the anticoagulant activity in patients treated with a Factor Xa inhibitor who suffer an uncontrolled 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. Our fourth program, PRT2607 and other selective Syk inhibitors, is being developed in partnership with Biogen Idec Inc.
	Initial Public and Follow-on Offering
	In May 2013, we closed our initial public offering (“IPO”) of 9,686,171 shares of our common stock, which included 1,263,413 shares of common stock issued pursuant to the over-allotment option granted to our underwriters. The public offering price of the shares sold in the offering was $14.50 per share. The total proceeds from the offering to us, net of underwriting discounts and commissions of approximately $9.4 million, were approximately $131.0 million. After deducting offering expenses payable by us of approximately $5.2 million, net proceeds to us were $125.8 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 24,026,797 shares of common stock. In addition, all of our convertible preferred stock warrants were converted into warrants to purchase common stock.
	In October 2013, we completed a follow-on offering of 6,366,513 shares of our common stock, which included 1,908,803 shares of common stock sold by certain existing stockholders, at a public offering price of $23.75 per share. In November 2013, the underwriters exercised their over-allotment option to purchase an additional 954,976 shares from us at the public offering price. The total proceeds from the offering and over-allotment option, net of underwriting discounts and commissions of approximately $7.7 million, were approximately $120.8 million. After deducting offering expenses of approximately $862,000, net proceeds to us were $119.9 million.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	Use of Estimates
	The preparation of 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 our 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 (loss). 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, net. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest and other income, net.
	Fair Value Measurements
	Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually).
	Concentration of Credit Risk
	Financial instruments that potentially subject us to concentrations of credit risk consist of cash, cash equivalents, receivables from collaborations and investments. Our investment policy limits investments to certain types of debt securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. We are exposed to credit risk in the event of a default by the financial institutions holding our cash, cash equivalents and investments and issuers of investments to the extent recorded on the balance sheets.
	Receivables from collaborations are typically unsecured and are concentrated in the pharmaceutical industry. Accordingly, we may be exposed to credit risk generally associated with pharmaceutical companies or specific to our collaboration agreements. To date, we have not experienced any losses related to these receivables.
	Customer Concentration
	Customers that accounted for 10% or more of total revenues were as follows:
		Year Ended December 31,
		2013		2012		2011
	Bristol-Myers Squibb Company and Pfizer Inc.		38%	–		–
	Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		37%	–		–
	Daiichi Sankyo, Inc		23%	–		–
	Novartis, AG	–			97%		12%
	Biogen Idec	–		–			48%
	Merck & Co., Inc.	–		–			40%
	Property and Equipment
	Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets, ranging from two to five years. Leasehold improvements are amortized over the shorter of their estimated useful lives or the related lease term.
	Impairment of Long-Lived Assets
	We review long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is assessed using discounted cash flows or other appropriate measures of fair value. Through December 31, 2013, there have been no such losses.
	Deferred Offering Costs
	Deferred offering costs, which primarily consist of direct incremental legal, accounting and printing fees incurred in the preparation of the IPO, were capitalized. The deferred offering costs were offset against IPO proceeds upon completion of the offering in May 2013. As of December 31, 2012, $1.6 million of deferred offering costs were capitalized in other assets on the balance sheets. There were no remaining amounts deferred at December 31, 2013.
	Convertible Preferred Stock
	We recorded all shares of convertible preferred stock at their respective fair values on the dates of issuance. As of December 31, 2012, convertible preferred stock was classified outside of stockholders’ equity (deficit) on the balance sheet as events triggering the liquidation preferences were not solely within the Company’s control. Upon the closing of the IPO, all shares of our convertible preferred stock then outstanding converted into 24,026,797 shares of our common stock.
	Convertible Preferred Stock Warrant Liability
	Warrants for shares that are puttable and warrants for shares that are contingently redeemable are classified as liabilities on the accompanying balance sheets and carried at their estimated fair value. At the end of each reporting period, any changes in fair value are recorded as a component of interest and other income, net. We continued to adjust the carrying value of the warrants until the closing of the IPO, at which time the warrants became exercisable for shares of our common stock and were reclassified to stockholders’ equity (deficit).
	Deferred Rent
	We recognize rent expense on a straight-line basis over the noncancelable term of our operating lease and, accordingly, record the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. We also record lessor-funded lease incentives, such as reimbursable leasehold improvements, as a deferred rent liability, which is amortized as a reduction of rent expense over the noncancelable term of our operating lease.
	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 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 and obligations to participate on certain development and/or commercialization committees with the collaborators.
	On January 1, 2011, we adopted an accounting standards update that amends the guidance on accounting for new arrangements or those materially modified, with multiple deliverables. This guidance eliminates the requirement for objective and reliable evidence of fair value of the undelivered items in order to consider a deliverable a separate unit of accounting. It also changes the allocation method such that the relative-selling-price method must be used to allocate arrangement consideration to the units of accounting in an arrangement. This guidance establishes the following estimation hierarchy that must be used in estimating selling price under the relative-selling-price method: (1) vendor-specific objective evidence of fair value of the deliverable, if it exists, (2) third-party evidence of selling price, if vendor-specific objective evidence is not available or (3) vendor’s best estimate of selling price, if neither vendor-specific nor third-party evidence is available. The adoption of this guidance had a material effect on the revenue recognized for the year ended December 31, 2011 (see Note 7). For multiple element arrangements entered into prior to January 1, 2011, we determined whether the elements had stand-alone value and whether there was objective and reliable evidence of fair value. When the delivered element did not have stand-alone value or there was insufficient evidence of fair value for the undelivered element(s), we recognized the consideration for the combined unit of accounting in the same manner as the revenue was recognized for the final deliverable, which was on a straight-line basis over the estimated period of performance.
	On January 1, 2011, we adopted an accounting standards update that provides guidance on revenue recognition using the milestone method. 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.
	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.
	Research and Development
	Research and development costs are expensed as incurred and consist of salaries and benefits, lab supplies, materials and facility costs, as well as fees paid to other nonemployees and entities that conduct certain research and development activities on our behalf. Amounts incurred in connection with collaboration and license agreements are also included in research and development expense. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received.
	Clinical Trial Accruals
	Clinical trial costs are a component of research and development expenses. We accrue and expense clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. We determine the actual costs through monitoring patient enrollment and discussions with internal personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.
	Stock-Based Compensation
	Stock-based awards issued to employees, are recorded at fair value as of the grant date using the Black-Scholes option-pricing model and recognized as expense on a straight-line basis over the vesting period of the award. Because noncash stock compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates.
	Equity instruments issued to nonemployees, consisting of stock options granted to consultants, are valued using the Black-Scholes option-pricing model. Stock-based compensation expense for nonemployee services is subject to remeasurement as the underlying equity instruments vest and is recognized as an expense over the period during which services are received.
	Income Taxes
	We provide for income taxes under the asset and liability method. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating loss and credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized. The recognition, derecognition and measurement of a tax position is based on management’s best judgment given the facts, circumstances and information available at the reporting date. Our policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the underpayment of income taxes.
	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 interest and other income, net in the 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.
	Reverse Stock Split
	On May 17, 2013, we effected a 1-for-10 reverse split of our preferred stock and common stock. Upon the effectiveness of the reverse stock split every 10 shares of outstanding preferred stock and common stock was decreased to one share of preferred stock or common stock, as applicable, the number of shares of common stock into which each outstanding option to purchase common stock is exercisable was proportionately decreased on a 1-for-10 basis, and the exercise price of each outstanding option to purchase common stock was proportionately increased on a 1-for-10 basis. All the shares numbers, share prices and exercise prices have been adjusted within the financial statements, on a retroactive basis, to reflect the 1-for-10 reverse stock split.
	Net Income (Loss) per Share Attributable to Common Stockholders
	Basic and diluted net income (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	12 Months Ended
	Dec. 31, 2013
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, short-term investments, receivables and accounts payable, approximate their fair value due to their short maturities. 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.
	A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Where quoted prices are available in an active market, securities are classified as Level 1. We classify money market funds as Level 1. When quoted market prices are not available for the specific security, then we estimate fair value by using quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes and market reference data. We classify our corporate notes, commercial paper, U.S. government agency securities and foreign currency forward contracts as Level 2. 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.
	In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3. Our convertible preferred stock warrant liability was classified as Level 3. The fair values of the convertible preferred stock warrants were measured using the Black-Scholes option-pricing model. Inputs used to determine estimated fair value included the estimated fair value of the underlying preferred stock at the valuation measurement date, the remaining contractual term of the warrants, risk-free interest rates, expected dividends and estimated volatility. Estimated volatility is based on the volatility of our peer group. We monitor the historical volatility of peer group companies on a quarterly basis and adjust our estimated volatility when significant changes in the peer group volatilities occur. The significant unobservable input used in the fair value measurement of the convertible preferred stock warrant liability is the fair value of the underlying preferred stock at the valuation remeasurement date. Generally, increases (decreases) in the fair value of the underlying preferred stock would result in a directionally similar impact to the fair value measurement.
	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):
		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
		December 31, 2012
		Level 1			Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	43,303		$	-	$	-	$	43,303
	Corporate notes and commercial paper		-			64,425		-		64,425
	U.S. government agency securities		-			19,346		-		19,346
	Foreign currency forward contracts		-			51		-		51
	Total financial assets	$	43,303		$	83,822	$	-	$	127,125
	Financial Liabilities:
	Convertible preferred stock warrant liability	$	-		$	-	$	683	$	683
	Level 3 liabilities include the convertible preferred stock warrant liability (see Note 10). The following table sets forth a summary of the changes in the estimated fair value of our convertible preferred stock warrants, which were measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2010	$	789
	Recognized gain		(23	)
	Balance as of December 31, 2011		766
	Recognized gain		(83	)
	Balance as of December 31, 2012		683
	Recognized gain		(24	)
	Balance as of December 31, 2013	$	-
	The recognized gain was included in interest and other income, net.

Financial_Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2013
Financial Instruments	'
	4. Financial Instruments
	Cash equivalents and short-term and long-term investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):
		December 31, 2013									December 31, 2012
									Estimated									Estimated
				Unrealized		Unrealized			Fair				Unrealized		Unrealized			Fair
		Cost		Gain		(Loss)			Value		Cost		Gain		(Loss)			Value
	Money market funds	$	57,296	$	-	$	-		$	57,296	$	43,303	$	-	$	-		$	43,303
	Corporate notes and commercial paper		182,426		62		(16	)		182,472		64,403		25		(3	)		64,425
	U.S. government agency securities		75,278		23		(12	)		75,289		19,335		11		-			19,346
		$	315,000	$	85	$	(28	)	$	315,057	$	127,041	$	36	$	(3	)	$	127,074
	Classified as:
	Cash equivalents								$	113,794								$	43,303
	Short-term investments									150,892									77,656
	Long-term investments									50,371									6,115
	Total cash equivalents and investments								$	315,057								$	127,074
	At 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	12 Months Ended
	Dec. 31, 2013
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 December 31,2013 and 2012, we had foreign currency forward contracts with notional amounts of €7.7 million ($10.6 million based on the exchange rate as of December 31, 2013) and €16.8 million ($22.2 million based on the exchange rate as of December 31, 2012), respectively. As of December 31, 2013, we recorded a derivative asset within prepaid expenses and other current assets of $372,000 related to these foreign currency forward contracts. As of December 31, 2012, we recorded a derivative asset with prepaid expenses and other current assets and other long-term assets of $30,000 and $21,000, respectively.
	For the years ended December 31, 2013 and 2012, we recorded an unrealized gain of $261,000 and $51,000, respectively, in interest and other income, net on our statement of operations related to these foreign currency forward contracts. During the year ended December 31, 2013, we settled foreign currency forward contracts and recognized a realized gain of $60,000 in interest and other income (expense), net. No realized gains or losses were recorded for the year ended December 31, 2012 related to these foreign currency contracts.
	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	12 Months Ended
	Dec. 31, 2013
Balance Sheet Components	'
	6. Balance Sheet Components
	Property and Equipment
	Property and equipment consists of the following (in thousands):
		December 31,
		2013			2012
	Computer equipment	$	618		$	515
	Capitalized software		463			423
	Equipment		3,690			3,224
	Leasehold improvements		3,988			3,499
			8,759			7,661
	Less accumulated depreciation and amortization		(6,159	)		(4,800	)
	Property and equipment, net	$	2,600		$	2,861
	Accrued and Other Liabilities
	Accrued and other liabilities consist of the following (in thousands):
		December 31,
		2013			2012
	Research and development related	$	16,110		$	4,217
	Legal and accounting fees		462			1,523
	Deferred rent		879			831
	Other		345			828
	Total accrued liabilities	$	17,796		$	7,399

Collaboration_and_License_Agre

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2013
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):
		Year Ended December 31,
		2013		2012		2011
	Novartis:
	Recognition of upfront license fee	$	-	$	53,846	$	7,692
	Reimbursement of research and development expense		-		16,238		1,879
	Novartis total		-		70,084		9,571
	Merck:
	Recognition of upfront license fee				-		21,429
	Reimbursement of research and development expense		-		-		9,973
	Merck total		-		-		31,402
	Biogen Idec:
	Recognition of upfront license fee		-		-		37,056
	Biogen Idec total		-		-		37,056
	BMS and Pfizer:
	Recognition of research and development services		4,042		1,958		-
	BMS and Pfizer total		4,042		1,958		-
	Bayer and Janssen:
	Recognition of research and development services		3,876		-		-
	Bayer and Janssen total		3,876		-		-
	Lee’s:
	Recognition of research and development services		194		-		-
	Lee’s total		194		-		-
	Daiichi Sankyo:
	Recognition of research and development services		2,419
	Daiichi Sankyo total		2,419		-		-
	Total collaboration and license revenue	$	10,531	$	72,042	$	78,029
	Novartis Pharma A.G. (“Novartis”)
	In February 2009, we entered into an exclusive worldwide license agreement with Novartis to develop and commercialize Elinogrel, which was amended in December 2010 and terminated effective July 1, 2012. Under the terms of the license agreement, Novartis made an upfront cash payment to us of $75.0 million in exchange for an exclusive worldwide license to develop and commercialize Elinogrel. We were eligible to receive additional cash payments totaling up to $505.0 million upon achievement by Novartis of certain development, regulatory and commercialization milestones. We were obligated to participate on a Joint Steering Committee and a Joint Development Committee (collectively, the “Committees”) with Novartis through December 31, 2018, to oversee development activities related to Elinogrel, unless Novartis agreed to disband the Committees at an earlier date. Pursuant to the license agreement, Novartis was obligated to fund development and commercialization expenses for Elinogrel after January 1, 2009, except for the first $18.0 million of Phase 2 clinical trial costs and selected tasks, which we were obligated to fund.
	Novartis had the exclusive right to market and sell drugs developed pursuant to the license agreement and was obligated to pay us tiered royalties at specified rates on net sales for each product. Under the license agreement, we had the right to elect to co-fund the development costs for the Phase 3 clinical trial in exchange for higher royalty payments and had the right to co-promote, in the United States, drugs developed pursuant to the license agreement in exchange for compensation for such co-promotion effort (on a fee-for-service basis).
	We identified the following performance obligations under the license agreement with Novartis: 1) the transfer of intellectual property rights (license), 2) the obligation to provide certain limited research and development services early during the term of the license agreement and 3) the obligation to participate on the Committees. We accounted for these deliverables in accordance with accounting rules applicable to arrangements entered into prior to January 1, 2011 as a single unit of accounting, as there was no objective and reliable evidence of the fair value of our undelivered performance obligation with respect to participation on the Committees. Consideration under the license agreement consisted of an upfront license fee, milestone payments, research and development funding and royalties (if and when commercialization occurs). The amounts we received from Novartis for the upfront license fee and collaborative research efforts are recognized as collaboration revenue on a straight-line basis from the effective date of payment over the remainder of the expected performance period. Royalties on net sales will generally be recognized when royalty amounts can be reasonably estimated. No milestones have been reached since the inception of the Novartis agreement.
	We estimated the term of our obligation to participate in the Committees to extend through December 31, 2018. In April 2012, we and Novartis agreed to a plan to return all rights to Elinogrel to Portola and to terminate the exclusive worldwide license agreement effective July 1, 2012. In connection with this plan, the expected term of our obligation to participate in the Committees changed from December 31, 2018 to July 1, 2012. The change in term of the obligation to participate in the Committees was accounted for as a change in accounting estimate on a prospective basis effective April 1, 2012. The change resulted in a $65.1 million increase in collaboration revenue due to the recognition of all remaining revenue that would have otherwise been recorded over the obligation period through December 31, 2018. Absent this acceleration, the net income for the year ended December 31, 2012 would have been lower by $65.1 million, resulting in a net loss of $53.7 million and net loss per share would have been $3.98 compared to net income per share of $0.00 as reported. As a result of terminating the agreement, all remaining deferred revenue was recognized immediately, as no further performance obligations remained upon termination. As of the time of termination, no milestones had been achieved and no royalties had been triggered under our agreement with Novartis.
	Merck & Co., Inc. (“Merck”)
	In July 2009, we entered into an exclusive worldwide license agreement with Merck to develop and commercialize Betrixaban, which was terminated effective September 30, 2011. Under the terms of the agreement, Merck made an upfront cash payment to us of $50.0 million in August 2009 in exchange for an exclusive worldwide license to develop and commercialize Betrixaban. We were eligible to receive additional cash payments totaling as much as $420.0 million upon achievement by Merck of certain development, regulatory and commercialization milestones under the agreement.
	We identified the following performance obligations under the license agreement with Merck: 1) the transfer of intellectual property rights (license), 2) the obligation to provide certain limited research and development services early during the term of the license agreement and 3) the obligation to participate on the Committees. We accounted for these deliverables in accordance with accounting rules applicable to arrangements entered into prior to January 1, 2011 as a single unit of accounting as there was not objective and reliable evidence of the fair value of our undelivered performance obligation with respect to participation on the Committees. Consideration under the license agreement consisted of an upfront license fee and research and development funding and could have also included milestone payments and royalties (if certain development and commercialization events occurred). Amounts received by us from Merck for the upfront license fee and collaborative research efforts were recognized as collaboration revenue on a straight-line basis from the date of payment over the remainder of the expected performance period.
	In March 2011, we and Merck agreed to a plan to return all rights to Betrixaban to Portola and to terminate the exclusive worldwide license agreement effective September 2011. As a result of the termination of the agreement, all remaining deferred revenue was recognized immediately, as no further performance obligations remained upon termination. As of the time of termination, no milestones had been achieved and no royalties had been triggered under our agreement with Merck.
	Biogen Idec, Inc. (“Biogen Idec”)
	In October 2011, we entered into an exclusive, worldwide license and collaboration agreement with Biogen Idec, which was subsequently converted by its terms into a fully out-licensed agreement, under which Portola and Biogen Idec were to jointly develop and commercialize highly selective, novel oral Syk inhibitors for the treatment of autoimmune and inflammatory diseases, including rheumatoid arthritis, allergic asthma and systemic lupus erythematosus.
	We led the initial development effort for the Syk inhibitor program until commencement of the first Phase 2 clinical trial in late 2012. At that time, Biogen Idec assumed responsibility to lead the global development and commercialization efforts in major indications such as rheumatoid arthritis and allergic asthma. We had the option to elect to lead U.S. development and commercialization efforts for select smaller indications as well as discovery efforts for follow-on Syk inhibitors and retained an option to co-promote the drug alongside Biogen Idec in the United States in major indications. On a product-by-product basis, we had and exercised an option to opt out of our co-funding obligation of the development of such product. Pursuant to this option, we also relinquished our right to share profits from sales of such product(s), but are entitled to receive royalties from Biogen Idec’s sales of these products.
	Under the terms of the agreement, Biogen Idec provided us with a non-refundable upfront cash license fee of $36.0 million and paid $9.0 million for the purchase of 636,042 shares of our Series 1 convertible preferred stock at a premium of $1.1 million above the stock’s estimated fair value. In addition, we estimated that the agreement would provide $22.9 million for the partial reimbursement of certain research and development services and related committee participation and delivery of drug materials. The original agreement also provided for additional payments of up to $508.5 million based on the achievement of certain development and regulatory events. The $508.5 million includes one milestone of $23.0 million for commencement of the first Phase 2 trial which is considered substantive as its achievement is subject to the uncertain outcome of our development efforts over an extended period of time. All remaining payments would be associated with development and regulatory events that would be accomplished primarily based upon the performance of Biogen Idec, specifically, progress of development to Phase 3 clinical trials and filing and approval of drug applications by regulatory authorities in various countries. Accordingly, all other contingent consideration of $485.5 million was to be allocated to the identified performance deliverables when received and recognized when those performance deliverables are completed. If the performance deliverables are fully completed at the time payment is received, such amounts would be recognized upon receipt.
	We identified the following four non-contingent performance deliverables under the license agreement: 1) the transfer of intellectual property rights (license), 2) the obligation to provide research and development services, 3) the manufacture of drug material for development purposes, until commencement of the first Phase 2 clinical trial and 4) the obligation to participate on various committees. We have the right to opt out of any committees at any time after November 2013. The agreement states that consideration for the first two deliverables is $36.0 million and $22.9 million, respectively. There was no separate consideration identified in the agreement for the last two deliverables noted above. We are also required to contribute certain materials that we had previously acquired at a cost of approximately $1.0 million to the collaboration for research and development use.
	We considered the provisions of the multiple-element arrangement guidance in determining whether the deliverables outlined above have standalone value. We believe that Biogen Idec has research and development expertise with compounds similar to those licensed under the agreement and has the ability to engage other third parties to develop these compounds allowing Biogen Idec to realize the value of the license without receiving any of the remaining deliverables. Additionally, under the agreement, Biogen Idec has the right to sublicense this license to third parties, substantially with all the same rights and responsibilities. Therefore, the research and development services, participation in committee activities and provision of drug materials are deemed to have standalone value as Biogen Idec could negotiate for and/or acquire these from other third parties. Although participation in committee activities and provision of drug materials have standalone value, they will be delivered and utilized as the research and development services are performed and have a similar pattern of performance. These three deliverables are combined as one unit of accounting. There are no rights of return under the agreement.
	The upfront license fee of $36.0 million, the premium on the purchase of our Series 1 convertible preferred stock of $1.1 million and research and development expense reimbursements of $22.9 million were allocated to the two separate units of accounting using the relative estimated selling price method.
	We developed our best estimates of selling prices for each deliverable in order to allocate the noncontingent arrangement consideration to the two units of accounting. For the license, we used the discounted cash flow method to estimate the price at which we could sell the license on a standalone basis. Embedded in the estimate were significant assumptions regarding probabilities of success during the development process, data regarding the potential customer market for the drug and costs of development and manufacturing and the discount rate. For the combined unit of accounting, we considered the estimated selling price of each deliverable within that unit. That is, for research and development services and committee participation, we estimated selling prices based on personnel and other costs incurred in the delivery of the services, plus an estimated margin on sales of such services on a standalone basis. For the contributed drug materials, we estimated the selling price based on our cost to purchase such materials from our third party supplier.
	The arrangement consideration allocated to the license was recognized as collaboration and license revenue upon delivery in 2011. The amount allocated to the research and development services, materials and committee participation unit of accounting is being recognized over our estimated non-cancellable performance period of two years as a reduction to research and development expense. Under the terms of the agreement, we and Biogen Idec jointly shared development responsibilities prior to the conversion of this agreement into a fully out-licensed agreement, as if the two parties to the agreement incurred those costs directly.
	Based upon the relative estimated selling prices for the two units of accounting for the year ended December 31, 2011, we recognized collaboration revenue of $37.1 million and recorded a reduction in research and development expense for amounts owed by Biogen Idec to us under the cost-sharing terms of the agreement totaling $734,000.
	Under the previous accounting guidance for multiple element arrangements, we would have recognized revenues of approximately $3.4 million from the Biogen Idec arrangement for the year ended December 31, 2011. We would have concluded that all deliverables should be combined into a single unit of accounting in the absence of objective and reliable evidence of fair value of undelivered services and recognized over an estimated performance period through November 2013.
	In November 2012, we elected to exercise our option under our agreement with Biogen Idec to convert the agreement to a fully out-licensed agreement. After such election, we relinquished our right to share profits from sales of products related to PRT2607 and other selective Syk inhibitors, but are entitled to receive royalties from sales of these products by Biogen Idec. We no longer have the responsibility 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. 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 in force until either party terminates the agreement pursuant to the agreement or until the expiration of Biogen Idec’s royalty obligations pursuant to 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.
	During the years ended December 31, 2013 and 2012, we recorded a reduction in research and development expense of $804,000 and $6.5 million, respectively, owed by Biogen Idec to us under the cost-sharing terms of the agreement.
	As of December 31, 2013, the one milestone in the agreement had not been achieved and no royalties had been triggered under this 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. We are responsible for the cost of conducting this clinical study. BMS and Pfizer will work closely with us on both development and regulatory aspects of Andexanet alfa in connection with our Phase 2 proof-of-concept studies to the extent such matters relate to apixaban. Pursuant to our agreement with BMS and Pfizer we are obligated to provide research and development services and participate on various committees. We originally estimated the period of performance of our obligations to extend through the second quarter 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 revised our estimated period of performance to be through the fourth quarter of 2013. The effects of these changes in estimates were not significant.
	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. For the year ended December 31, 2013 and 2012, we recognized $4.0 and $2.0 million in collaboration revenue, respectively.
	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 have not been material.
	For the year ended December 31, 2013, we recognized $194,000 of collaboration revenue. The deferred revenue balance as of December 31, 2013 was $506,000.
	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 total consideration 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 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 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 as revenue on a straight-line basis over the estimated performance period through the fourth quarter of 2014.
	For the year ended December 31 2013, we recognized $3.9 million in collaboration revenue. The deferred revenue balance as of December 31, 2013 was $1.1 million.
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 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. 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 2013 no such costs have been incurred related to this agreement.
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 will provide us with an upfront fee of $6.0 million, $3.0 million of which is subject to refund should Daiichi Sankyo decide 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 contingent consideration under this agreement of $3.0 million will be recognized after the contingency is resolved over the remaining performance period, which is currently estimated to begin in the first quarter of 2014 and conclude in the first quarter of 2015.
During the year ended December 31, 2013, we recognized $2.4 million in collaboration revenue associated with the non-contingent element of the arrangement. The contingent element of the arrangement of $3.0 million and the unearned portion of the non-contingent element of the arrangement of $581,000 was recorded as deferred revenue as of December 31, 2013.

Asset_Acquisition_and_License_

Asset Acquisition and License Agreements	12 Months Ended
	Dec. 31, 2013
Asset Acquisition and License Agreements	'
	8. Asset Acquisition and License Agreements
	Millennium Pharmaceuticals, Inc. (“Millennium”)
	In November 2003, we acquired patent rights and intellectual property to an ADP Receptor Antagonist Program (“ADP Program”) and a Platelet Biology Program from Millennium. We are obligated to pay royalties on sales of products developed in the ADP Program if product sales are ever achieved.
	In August 2004, we licensed rights to research, develop and commercialize compounds that inhibit Factor Xa from Millennium. We also obtained a patent license, a license for know-how and a technology license related to the lead Factor Xa compound, Betrixaban. In December 2005, we amended our agreements with Millennium for the ADP Program and for the Factor Xa Program. The effect of this amendment modified Millennium’s Right of First Negotiation in each agreement from an exclusive right to negotiate development and commercial rights to a nonexclusive right to negotiate.
	In November 2007, we elected to continue our development of Betrixaban and the Factor Xa backup chemistry beyond December 1, 2007 and accordingly, paid $5.0 million in cash to Millennium, which was charged to research and development expense, as the rights had no alternative future use. We could owe Millennium up to $35.0 million upon the occurrence of specified events related to Betrixaban and royalties on sales of Factor Xa products, if such product sales are ever achieved.
	As a result of entering into definitive agreements with third parties during 2009 for the development (and possibly commercialization) of both Elinogrel and Betrixaban, we paid Millennium an additional $250,000 in cash and issued 17,667 shares of Series C convertible preferred stock with a fair value of $14.15 per share. The value ascribed to the shares issued to Millennium was based upon the sale of our Series C convertible preferred stock at $14.15 per share in May 2009 to an external investor. The value of the Series C convertible preferred stock of approximately $250,000 was charged to research and development expense.
	Astellas Pharma, Inc. (“Astellas”)
	In June 2005, we licensed certain rights to research, develop and commercialize Syk inhibitors, including Cerdulatinib, from Astellas. In December 2008, under the terms of the license agreement, we elected to continue our development of Syk inhibitors and, accordingly, paid $1.0 million in cash to Astellas, which was charged to research and development expense as the rights had no alternative future use.
	In 2011, under the terms of the license agreement and in connection with the Biogen Idec collaboration agreement to develop Syk, we paid $7.2 million in cash to Astellas, which was charged to research and development expense as the rights had no alternative future use.
	We may be required to pay Astellas up to $71.5 million upon the achievement of certain regulatory, approval and sales events for each Syk inhibitor we develop. In the event that we enter into an agreement with a third party to develop and commercialize Syk inhibitors, we would be required to pay Astellas 20% of any payments (excluding royalties) received under the collaboration. These payments would be creditable against the aforementioned milestone payments. In addition, we are required to pay Astellas royalties for worldwide sales for any commercial Syk inhibitor product.

Restructuring_Charge

Restructuring Charge	12 Months Ended
	Dec. 31, 2013
Restructuring Charge	'
	9. Restructuring Charge
	In November 2012, as part of our strategy to better align our capital resources with our clinical development plan, we reduced our workforce by 23 employees, 16 of whom were immediately terminated, five of whom were terminated on January 31, 2013, and two of whom were terminated on April 30, 2013. The final restructuring charge of $698,000 includes severance and related costs associated with the termination of the employees. For the year ending December 31, 2013, we recorded a net restructuring charge of $79,000, of which $66,000 is included within research and development expense and $13,000 is included within general and administrative expense on our statement of operations. During the year ended December 31, 2013, we paid $223,000 of severance costs. At December 31, 2012, the accrued restructuring liability, which is included within accrued and other liabilities on the balance sheet was $143,000. There were no remaining amounts accrued for the restructuring liability at December 31, 2013.

Convertible_Preferred_Stock_Wa

Convertible Preferred Stock Warrant Liability	12 Months Ended
	Dec. 31, 2013
Convertible Preferred Stock Warrant Liability	'
	10. Convertible Preferred Stock Warrant Liability
	Upon closing of the IPO, all convertible preferred stock warrants converted into warrants to purchase shares of common stock at a conversion rate of 1-for-1 and the estimated liability was reclassified to additional paid-in capital. The following table sets forth the estimated fair value for each of the convertible preferred stock warrants as of May 22, 2013, the date of the final remeasurement before reclassifying the liability to APIC, and December 31, 2012 (in thousands, except share and per share data):
								Shares as of		Estimated Fair Value
				Exercise
	Preferred			Price				May 22,	December 31,	May 22,		December 31,
	Stock	Expiration Date		Per Share				2013	2012	2013		2012
	Series A	Later of: (i) January 20, 2015 or (ii) 3 years after the closing of an initial public offering of our common stock		$	10			4,740	4,740	$	35	$	36
	Series B	Later of: (i) September 28, 2016 or (ii) 5 years after the closing of an initial public offering of our common stock		$	13.1			76,335	76,335		624		647
	Total							81,075	81,075	$	659	$	683
	The estimated fair value of the above warrants was determined using the Black-Scholes option-pricing model using the following assumptions:
		May 22,				December 31,
		2013				2012
	Risk-free interest rate	0.1 - 0.9%				0.3 - 0.6%
	Estimated term equal to the remaining contractual term	1.7 - 3.8 years				2.1 - 4.2 years
	Volatility		79%				82%
	Dividend yield	–				–

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies	'
	11. Commitments and Contingencies
	We conduct product research and development programs through a combination of internal and collaborative programs that include, among others, arrangements with universities, contract research organizations and clinical research sites. We have contractual arrangements with these organizations; however, these contracts are cancelable on 30 days’ notice and our obligations under these contracts are largely based on services performed with the exception of our contract manufacturers where we have committed to $5.2 million in services to be performed in 2014.
	Facility Leases
	We lease our corporate, laboratory and other facilities under an operating lease, which was extended in May 2010 through March 31, 2015. The 2010 lease amendment provided for tenant improvement allowances of $3.2 million, which are amortized as a reduction to rent expense on a straight-line basis over the lease term. The facility lease agreement, as amended, contains scheduled rent increases over the lease terms. Under the 2010 lease amendment, we have an option to extend the lease for an additional three-year term. The related rent expense for this lease is calculated on a straight-line basis, with the difference recorded as deferred rent.
	At December 31, 2013, our future minimum commitments under our non-cancelable operating leases were as follows (in thousands):
	Year ending December 31:
	2014	$	1,660
	2015		418
	Total	$	2,078
	Rent expense was $803,000, $800,000 and $1.0 million for the years ended December 31, 2013, 2012 and 2011, respectively.
	Guarantees and Indemnifications
	We indemnify each of our officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at our request in such capacity, as permitted under Delaware law and in accordance with our certificate of incorporation and bylaws. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.
	The maximum amount of potential future indemnification is unlimited; however, we currently hold director and officer liability insurance. This insurance allows the transfer of risk associated with our exposure and may enable us to recover a portion of any future amounts paid. We believe that the fair value of these indemnification obligations is minimal. Accordingly, we have not recognized any liabilities relating to these obligations for any period presented.

Convertible_Preferred_Stock_an

Convertible Preferred Stock and Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2013
Convertible Preferred Stock and Stockholders' Equity (Deficit)	'
	12. Convertible Preferred Stock and Stockholders’ Equity (Deficit)
	Convertible Preferred Stock
	As of December 31, 2013, no shares of convertible preferred stock were outstanding. The authorized, issued, and outstanding shares of convertible preferred stock at December 31, 2012 were as follows:
		Shares		Shares		Carrying
		Authorized		Issued and		Value and
				Outstanding		Liquidation
						Preference
	Series A	43,147,400		4,309,972		$	43,100
	Series B	36,750,400		3,579,597			46,893
	Series C	93,000,000		9,214,160			130,381
	Series D	64,000,000		6,287,026			88,962
	Series 1	6,360,500		636,042			7,944
	Total	243,258,300		24,026,797		$	317,280
	Conversion
	The preferred stock was convertible at the option of the holder at any time into fully paid, nonassessable shares of common stock. The number of shares of common stock to which a holder was entitled upon conversion was the product obtained by multiplying the preferred conversion rate (the original issue price divided by the convertible preferred stock conversion price (the original issue price, subject to certain adjustments for antidilution)) by the number of shares being converted.
	Each share of convertible preferred stock automatically converted into common stock upon closing of our IPO. Our Amended and Restated Certificate of Incorporation currently authorizes 5,000,000 shares of preferred stock, none of which have been issued by us or designated by our board of directors. A description of certain rights applicable to shares of convertible preferred stock prior to their conversion in our IPO is as follows:
	Voting Rights
	With the exception of the holders of Series 1 convertible preferred stock, which had no voting rights, the holders of each share of convertible preferred stock had one vote for each share of common stock into which such convertible preferred stock could have been converted.
	Holders of Series D convertible preferred stock were granted a separate vote. In addition to any other vote or consent required, the vote or written consent of the holders of at least 50% of the outstanding Series D convertible preferred stock would have been necessary for effecting or validating certain actions as were previously outlined in our Certificate of Incorporation before it was amended and restated in connection with our IPO.
	Dividends and Distributions
	The holders of the convertible preferred stock were entitled to receive, when, as and if declared by the Board of Directors, a noncumulative cash dividend at the annual rate of 8% of the original issue price per annum on each outstanding share of convertible preferred stock. The original issue price is $10.00 for Series A, $13.10 for Series B and $14.15 for Series C, Series D and Series 1. Such dividends were to be payable only when, as and if declared by the Board of Directors. After payment of dividends at the rate set forth above, any additional dividends declared would have been distributed among all holders of convertible preferred stock and common stock in proportion to the number of shares of common stock that would have then been held by each such holder if all shares of convertible preferred stock were converted into common stock. No dividends were declared prior to the conversion of all shares of preferred stock into shares of common stock in connection with the closing of our IPO.
	Liquidation Rights
	Upon liquidation, dissolution, or winding up of the Company (whether voluntary or involuntary) (a “Liquidation Event”), before any distribution or payment was to be made to the holders of any Series A, Series B, Series C or Series 1 convertible preferred stock or common stock, the holders of Series D convertible preferred stock would have been entitled to be paid out of our assets legally available for distribution, an amount equal to the original purchase price of the Series D convertible preferred stock plus all declared and unpaid dividends. The holders of Series A, Series B, Series C and Series 1 convertible preferred stock would have been entitled to receive, prior and in preference to any distribution of any of our assets legally available for distribution to the holders of common stock, an amount equal to the respective original purchase price of such series of convertible preferred stock plus all declared and unpaid dividends. After payments of the full liquidation preferences of the Series A, Series B, Series C, Series D and Series 1 convertible preferred stock described above, the remaining assets of the Company would have been available for distribution to stockholders.
	Warrants
	At December 31, 2013, warrants to purchase 82,575 shares of common stock were outstanding at exercise prices ranging between $10.00 and $13.10 per share and are exercisable through 2018. No warrants were granted, exercised or canceled during 2013.
	Equity Incentive Plan
	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. The 2013 Plan has 81,948 shares of common stock available for future issuance as of December 31, 2013, subject to automatic annual increases beginning on January 1, 2014 through January 1, 2023. Further, all remaining shares available under the 2003 Equity Incentive Plan, or the 2003 Plan, were transferred to the 2013 Plan upon adoption. The 2013 Plan provides for the granting of incentive stock options, nonstatutory stock options, stock bonuses and rights to acquire restricted stock to employees, officers, directors and consultants. Incentive stock options may be granted with exercise prices of not less than 100% of the estimated fair value of our common stock and nonstatutory stock options may be granted with an exercise price of not less than 85% of the estimated fair value of the common stock on the date of grant. Stock options granted to a stockholder owning more than 10% of our voting stock must have an exercise price of not less than 110% of the estimated fair value of the common stock on the date of grant. Stock options are generally granted with terms of up to ten years and vest over a period of four years.
	As of December 31, 2013, 4,903,323 shares of common stock were reserved under the 2013 Plan for the issuance of options and restricted stock.
	A summary of Portola’s stock option activity follows:
							Shares
							Subject to				Weighted-
			Shares Available				Outstanding				Average Exercise
			for Grant				Options				Price Per Share
	Balance at December 31, 2012			593,011				3,451,178			$	6.35
	Options authorized			150,000			–				–
	Options granted			(1,022,601	)			1,022,601				18.31
	Options exercised		–					(403,468	)			6.4
	Options canceled			361,538				(361,538	)			8.58
	Balance at December 31, 2013			81,948				3,708,773			$	9.43
	Additional information related to the status of options at December 31, 2013, is as follows (aggregate intrinsic value in thousands):
							Weighted-
							Average				Remaining
							Exercise Price				Contractual			Aggregate
			Shares				Per Share				Life			Intrinsic Value
	Outstanding and exercisable			3,708,773			$	9.43				6.5		$	60,600
	Vested and expected to vest			3,631,910			$	9.26				6.5		$	60,600
	Vested			2,324,788			$	6.33				5		$	45,199
	The aggregate intrinsic values of options outstanding and exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the fair value of our common stock as of December 31, 2013.
	The aggregate intrinsic value of options exercised was $6.3 million, $451,000 and $290,000 for the years ended December 31, 2013, 2012 and 2011, respectively.
	The total estimated grant date fair value of options vested during the years ended December 31, 2013, 2012 and 2011 was $3.8 million, $3.0 million and $1.8 million, respectively.
	Additional information regarding our stock options outstanding and vested and exercisable as of December 31, 2013 is summarized below:
			Options Outstanding and Exercisable							Options Vested
			Number of		Weighted
			Options		Average		Weighted			Number		Weighted
			Outstanding		Remaining		Average			of		Average
			and		Contractual		Exercise Price			Options		Exercise Price
	Exercise Prices		Exercisable		Life (Years)		per Share			Vested		Per Share
	$1.00 - $2.00		14,042		1.1		$	1.34		14,042		$	1.34
	$3.30		381,521		2.4			3.3		381,521			3.3
	$3.6 - $4.10		378,399		3.9			4.09		378,399			4.09
	$4.5 - $5.10		463,189		3.6			5.02		463,189			5.02
	$5.30		152,750		4.5			5.3		152,750			5.3
	$7.00		449,244		8.1			7		206,664			7
$8.50		416,921		7.2			8.5		270,056			8.5
$9.00		379,318		6.4			9		354,875			9
$9.5 - $10.90		406,068		9.2			10.05		26,693			9.75
$19.74 - $28.47		667,321		9.6			22.23		76,599			20.25
		3,708,773		6.5		$	9.43		2,324,788		$	6.33

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2013
Stock-Based Compensation	'
	13. Stock Based Compensation
	Stock-based compensation expense, net of estimated forfeitures, is reflected in the statements of operations as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Research and development	$	2,295		$	1,452		$	1,164
	General and administrative		2,679			1,357			1,189
	Total stock-based compensation	$	4,974		$	2,809		$	2,353
	As of December 31, 2013, total unamortized employee and nonemployee stock-based compensation was $12.5 million, which is expected to be recognized over the remaining vesting period of 2.8 years. The weighted-average grant date fair value of employee options granted during the years ended December 31, 2013, 2012 and 2011 was $12.46, $5.90 and $4.70 per share, respectively.
	Valuation Assumptions
	The employee stock-based compensation expense was determined using the Black-Scholes option valuation model. Option valuation models require the input of subjective assumptions and these assumptions can vary over time. The risk-free rate is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected terms of the awards. The expected term of employee options granted is determined using the simplified method (based on the midpoint between the vesting date and the end of the contractual term). As sufficient trading history does not yet exist for our common stock, our estimate of expected volatility is based on the volatility of other companies with similar products under development, market, size and other factors. To date, we have not declared or paid any cash dividends and do not have any plans to do so in the future. Therefore, we used an expected dividend yield of zero.
	The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of options granted to employees:
		Year Ended December 31,
		2013		2012			2011
	Risk-free interest rate	1.43%		1.10%			1.10%
	Expected life	6.0 years		6.0 years			6.0 years
	Expected volatility	79%		72%			85%
	Dividend yield	–		–			–
	The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of ESPP purchase rights granted to employees:
		Year Ended December 31,
		2013		2012			2011
	Risk-free interest rate	0.10%		–			–
	Expected life	0.42 years		–			–
	Expected volatility	62%		–			–
	Dividend yield	–		–			–
	Options Granted to Nonemployees
	We have granted options to purchase shares of common stock to consultants in exchange for services performed. We granted options to purchase 32,943 and 6,380 shares with average exercise prices of $19.88 and $7.00 per share, respectively, during the years ended December 31, 2013 and 2012, respectively. These options vest upon grant or various terms up to four years. We recognized non-employees stock compensation expense of $775,000, $144,000 and $65,000 during the years ended December 31, 2013, 2012 and 2011, respectively. The fair value of non-employees’ options was measured using the Black-Scholes option-pricing model reflecting the same assumptions as applied to employee options in each of the reported years, other than the expected life, which is assumed to be the remaining contractual life of the option.
	Employee Stock Purchase Plan
	The Board of Directors adopted the 2013 Employee Stock Purchase Plan, effective upon the completion of Portola’s initial public offering of its common stock. Portola reserved a total of 1,000,000 shares of common stock for issuance under the plan. Eligible employees may purchase common stock at 85 percent of the lesser of the fair market value of Portola’s common stock on the first or last day of the offering period. The reserve for shares available under the plan will automatically increase on January 1st each year, beginning in 2014, by an amount equal to 2 percent of the total number of outstanding shares of our common stock on December 31st of the preceding fiscal year.

Net_Income_Loss_per_Share_Attr

Net Income (Loss) per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2013
Net Income (Loss) per Share Attributable to Common Stockholders	'
	14. Net Income (Loss) per Share Attributable to Common Stockholders
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Year Ended December 31,
		2013			2012			2011
	Convertible preferred stock	–				24,026,797			24,026,797
	Stock options to purchase common stock		3,708,773			1,653,298			962,225
	Convertible preferred stock warrants	–				81,075			81,075
	Common stock warrants		82,575			1,500			1,500
	The following table sets forth the computation of our basic and diluted net income (loss) per share attributable to common stockholders (in thousands, except share and per share data):
		Year Ended December 31,
		2013			2012			2011
	Net income (loss)	$	(83,352	)	$	11,366		$	19,984
	Noncumulative dividends on convertible preferred stock	–				(11,366	)		(18,757	)
	Undistributed earnings allocated to participating securities	–			–				(1,148	)
	Net income (loss) attributable to common stockholders, basic		(83,352	)		-			79
	Adjustment to undistributed earnings allocated to participating securities	–				-			48
	Net income (loss) attributable to common stockholders, diluted	$	(83,352	)	$	-		$	127
	Shares used in computing net income (loss) per share attributable to common stockholders, basic		22,842,443			1,350,939			1,249,778
	Dilutive effect of common stock options	–				697,928			839,428
	Shares used in computing net income (loss) per share attributable to common stockholders, diluted		22,842,443			2,048,867			2,089,206
	Net income (loss) per share attributable to common stockholders:
	Basic	$	(3.65	)	$	-		$	0.06
	Diluted	$	(3.65	)	$	-		$	0.06

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2013
Employee Benefit Plan	'
	15. Employee Benefit Plan
	We sponsor a 401(k) Plan, which stipulates that eligible employees can elect to contribute to the 401(k) Plan, subject to certain limitations of eligible compensation. We match employee contributions up to a maximum of $500 per employee each year. During the years ended December 31, 2013, 2012 and 2011, we recognized total expense of $59,000, $31,000 and $35,000, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Taxes	'
	16. Income Taxes
	We did not record a tax provision for the years ending December 31, 2013, 2012 and 2011. The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows:
		Year Ended December 31,
		2013			2012			2011
	Federal statutory income tax rate		34	%		34	%		34	%
	State income taxes, net of federal benefit		0.4			22.8			(3.8	)
	Federal and state research credits		3.4			0.8			(5.7	)
	Stock based compensation		(0.2	)		0.4			1.3
	Other		(0.5	)		(0.1	)		0.6
	Change in valuation allowance		(37.1	)		(57.9	)		(26.4	)
			0	%		0	%		0	%
	In 2012 and 2011, we did not record an income tax provision on pre-tax income because we incurred a current taxable loss for federal income tax purposes and had available tax credits to offset all state income tax. Tax credits were used in lieu of net operating losses because in 2012 and 2011 state law suspended their use. Our valuation allowance at December 31, 2013 and 2012 appropriately considers the balances of both net operating losses and deferred revenue.
	Significant components of our deferred tax assets are as follows (in thousands):
		December 31,
		2013			2012
	Deferred tax assets:
	Federal and state net operating loss carryforwards	$	102,478		$	74,390
	Federal and state research tax credit carryforwards		10,750			7,551
	Deferred revenue		1,755			1,434
	Stock options		2,895			2,362
	Capitalized acquisition costs		1,295			1,503
	Other		654			1,859
	Total deferred tax assets		119,827			89,099
	Valuation allowance		(119,827	)		(89,099	)
	Net deferred tax assets	$	-		$	-
	Realization of the deferred tax assets is dependent upon the generation of future taxable income, if any, the amount and timing of which are uncertain. Based on available objective evidence, including the fact that we have incurred significant losses in almost every year since our inception, management believes it is more likely than not that our deferred tax assets are not recognizable. Accordingly, deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $30.7 million for the year ended December 31, 2013. The valuation allowance decreased by $6.8 million for the year ended December 31, 2012.
	As of December 31, 2013, we had net operating loss carryforwards for federal income tax purposes of approximately $260.0 million and federal research tax credits of approximately $10.9 million, which expire at various dates in the period from 2023 to 2033. We also have state net operating loss carry forwards of approximately $227.6 million which expire at various dates in the period from 2014 to 2033 and state research tax credits of $2.4 million. Utilization of the net operating loss carryforwards and credits will be subject to an annual limitation due to the ownership change limitations provided by the Internal Revenue Code of 1986, as amended and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization.
	Uncertain Tax Positions
	We have not been audited by the Internal Revenue Service or any state tax authority. We are subject to taxation in the United States. Because of the net operating loss and research credit carryforwards, substantially all of our tax years, from 2003 through 2013, remain open to U.S. federal and California state tax examinations.
	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Unrecognized tax benefits, beginning of period	$	1,435		$	1,344		$	973
	Gross increases - current period tax positions		619			91			371
	Gross decreases - tax position in prior period		(6	)		-			-
	Unrecognized tax benefits, end of period	$	2,048		$	1,435		$	1,344
	The amount of unrecognized income tax benefits that, if recognized, would affect our effective tax rate was $365,000 as of December 31, 2013 and 2012. If the $2.0 million and $1.4 million of unrecognized income tax benefits as of December 31, 2013 and 2012, respectively, is recognized, there would be no impact to the effective tax rate as any change will fully offset the valuation allowance. We have classified the unrecognized tax benefits as long term, as we do not expect them to be realized over the next 12 months.
	We do not anticipate significant changes to our uncertain tax positions through the next 12 months.

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2013
Related Party Transactions	'
	17. Related Party Transactions
	Our former President and Chief Executive Officer, who is currently a member of our board of directors, is also a co-founder and member of the board of directors of Global Blood Therapeutics, Inc. (“Global Blood”), and a member of the board of directors of MyoKardia, Inc. (“MyoKardia”). In November 2012, we entered into Master Services Agreements with Global Blood and MyoKardia under which we provide certain consulting, preclinical, laboratory and clinical research related services to each of these companies. For the year ended December 31, 2013 and 2012, we recorded a reduction in research and development expense of $816,000 and $57,000, respectively, owed to us by Global Blood and Myokardia under the Master Services Agreements.
	As of December 31, 2013 and 2012, receivables from these related parties in the amount of $394,000 and $57,000, respectively, are included in prepaid expenses and other current assets on the balance sheet.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2013
Subsequent Events	'
	18. Subsequent Events
	In January 2014, 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 3 studies of Andexanet alfa. We are responsible for the cost of conducting this clinical study. BMS and Pfizer will work closely with us on both development and regulatory aspects of Andexanet alfa in connection with our Phase 3 study to the extent such matters relate to apixaban. Pursuant to our agreement with BMS and Pfizer we are obligated to provide research and development services and participate on various committees.
	The total consideration under this agreement of $25.0 million consists of a $13.0 million upfront payment and $12.0 million of payments due upon the achievement of certain milestones associated with the progress of our Phase 3 study.
	In January 2014, 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 3 studies of Andexanet alfa. We are responsible for the cost of conducting this clinical study. Bayer and Janssen will work closely with us on both development and regulatory aspects of Andexanet alfa in connection with our Phase 3 study to the extent such matters relate to rivaroxaban. Pursuant to our agreement with Bayer and Janssen, we are obligated to provide research and development services and participate on various committees.
	The total consideration under this agreement of $25.0 million consists of a $10.0 million upfront payment and $15.0 million of payments due upon the achievement of certain milestones associated with the progress of our Phase 3 study.

Quarterly_Financial_Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Data	'
	19. Quarterly Financial Data
	The following table presents certain unaudited quarterly financial information. This information has been prepared on the same basis as the audited financial statements and includes all adjustments (consisting only of normal recurring adjustments) necessary to present fairly the unaudited quarterly results of operations set forth herein. Net income (loss) per share for all periods presented have been retroactively adjusted to reflect the 1-for-10 reverse stock split effected on May 17, 2013. All data is in thousands except per share data.
		2013												2012
		Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
	Collaboration and license revenue	$	3,108		$	2,601		$	2,766		$	2,056		$	2,481		$	66,865		$	738		$	1,958
	Operating expenses	$	(20,761	)	$	(24,541	)	$	(21,995	)	$	(27,412	)	$	(15,768	)	$	(16,147	)	$	(12,833	)	$	(16,438	)
	Net income (loss)	$	(18,142	)	$	(21,598	)	$	(18,550	)	$	(25,062	)	$	(13,127	)	$	49,762		$	(11,488	)	$	(13,781	)
	Net income (loss) per share:
	Basic	$	(12.94	)	$	(1.47	)	$	(0.53	)	$	(0.63	)	$	(10.08	)	$	1.71		$	(8.38	)	$	(10.02	)
	Diluted	$	(12.94	)	$	(1.47	)	$	(0.53	)	$	(0.63	)	$	(10.08	)	$	1.67		$	(8.38	)	$	(10.02	)

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Use of Estimates	'
	Use of Estimates
	The preparation of 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 our 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 (loss). 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, net. The cost of securities sold is based on the specific-identification method. Interest on marketable securities is included in interest and other income, net.
Fair Value Measurements	'
	Fair Value Measurements
	Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually).
Concentration of Credit Risk	'
	Concentration of Credit Risk
	Financial instruments that potentially subject us to concentrations of credit risk consist of cash, cash equivalents, receivables from collaborations and investments. Our investment policy limits investments to certain types of debt securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. We are exposed to credit risk in the event of a default by the financial institutions holding our cash, cash equivalents and investments and issuers of investments to the extent recorded on the balance sheets.
	Receivables from collaborations are typically unsecured and are concentrated in the pharmaceutical industry. Accordingly, we may be exposed to credit risk generally associated with pharmaceutical companies or specific to our collaboration agreements. To date, we have not experienced any losses related to these receivables.
	Customer Concentration
	Customers that accounted for 10% or more of total revenues were as follows:
		Year Ended December 31,
		2013		2012		2011
	Bristol-Myers Squibb Company and Pfizer Inc.		38%	–		–
	Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		37%	–		–
	Daiichi Sankyo, Inc		23%	–		–
	Novartis, AG	–			97%		12%
	Biogen Idec	–		–			48%
	Merck & Co., Inc.	–		–			40%
Property and Equipment	'
	Property and Equipment
	Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets, ranging from two to five years. Leasehold improvements are amortized over the shorter of their estimated useful lives or the related lease term.
Impairment of Long-Lived Assets	'
	Impairment of Long-Lived Assets
	We review long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is assessed using discounted cash flows or other appropriate measures of fair value. Through December 31, 2013, there have been no such losses.
Deferred Offering Costs	'
	Deferred Offering Costs
	Deferred offering costs, which primarily consist of direct incremental legal, accounting and printing fees incurred in the preparation of the IPO, were capitalized. The deferred offering costs were offset against IPO proceeds upon completion of the offering in May 2013. As of December 31, 2012, $1.6 million of deferred offering costs were capitalized in other assets on the balance sheets. There were no remaining amounts deferred at December 31, 2013.
Convertible Preferred Stock	'
	Convertible Preferred Stock
	We recorded all shares of convertible preferred stock at their respective fair values on the dates of issuance. As of December 31, 2012, convertible preferred stock was classified outside of stockholders’ equity (deficit) on the balance sheet as events triggering the liquidation preferences were not solely within the Company’s control. Upon the closing of the IPO, all shares of our convertible preferred stock then outstanding converted into 24,026,797 shares of our common stock.
Convertible Preferred Stock Warrant Liability	'
	Convertible Preferred Stock Warrant Liability
	Warrants for shares that are puttable and warrants for shares that are contingently redeemable are classified as liabilities on the accompanying balance sheets and carried at their estimated fair value. At the end of each reporting period, any changes in fair value are recorded as a component of interest and other income, net. We continued to adjust the carrying value of the warrants until the closing of the IPO, at which time the warrants became exercisable for shares of our common stock and were reclassified to stockholders’ equity (deficit).
Deferred Rent	'
	Deferred Rent
	We recognize rent expense on a straight-line basis over the noncancelable term of our operating lease and, accordingly, record the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. We also record lessor-funded lease incentives, such as reimbursable leasehold improvements, as a deferred rent liability, which is amortized as a reduction of rent expense over the noncancelable term of our operating lease.
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 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 and obligations to participate on certain development and/or commercialization committees with the collaborators.
	On January 1, 2011, we adopted an accounting standards update that amends the guidance on accounting for new arrangements or those materially modified, with multiple deliverables. This guidance eliminates the requirement for objective and reliable evidence of fair value of the undelivered items in order to consider a deliverable a separate unit of accounting. It also changes the allocation method such that the relative-selling-price method must be used to allocate arrangement consideration to the units of accounting in an arrangement. This guidance establishes the following estimation hierarchy that must be used in estimating selling price under the relative-selling-price method: (1) vendor-specific objective evidence of fair value of the deliverable, if it exists, (2) third-party evidence of selling price, if vendor-specific objective evidence is not available or (3) vendor’s best estimate of selling price, if neither vendor-specific nor third-party evidence is available. The adoption of this guidance had a material effect on the revenue recognized for the year ended December 31, 2011 (see Note 7). For multiple element arrangements entered into prior to January 1, 2011, we determined whether the elements had stand-alone value and whether there was objective and reliable evidence of fair value. When the delivered element did not have stand-alone value or there was insufficient evidence of fair value for the undelivered element(s), we recognized the consideration for the combined unit of accounting in the same manner as the revenue was recognized for the final deliverable, which was on a straight-line basis over the estimated period of performance.
	On January 1, 2011, we adopted an accounting standards update that provides guidance on revenue recognition using the milestone method. 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.
	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.
Research and Development	'
	Research and Development
	Research and development costs are expensed as incurred and consist of salaries and benefits, lab supplies, materials and facility costs, as well as fees paid to other nonemployees and entities that conduct certain research and development activities on our behalf. Amounts incurred in connection with collaboration and license agreements are also included in research and development expense. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received.
Clinical Trial Accruals	'
	Clinical Trial Accruals
	Clinical trial costs are a component of research and development expenses. We accrue and expense clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. We determine the actual costs through monitoring patient enrollment and discussions with internal personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.
Stock-Based Compensation	'
	Stock-Based Compensation
	Stock-based awards issued to employees, are recorded at fair value as of the grant date using the Black-Scholes option-pricing model and recognized as expense on a straight-line basis over the vesting period of the award. Because noncash stock compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates.
	Equity instruments issued to nonemployees, consisting of stock options granted to consultants, are valued using the Black-Scholes option-pricing model. Stock-based compensation expense for nonemployee services is subject to remeasurement as the underlying equity instruments vest and is recognized as an expense over the period during which services are received.
Income Taxes	'
	Income Taxes
	We provide for income taxes under the asset and liability method. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating loss and credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized. The recognition, derecognition and measurement of a tax position is based on management’s best judgment given the facts, circumstances and information available at the reporting date. Our policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the underpayment of income taxes.
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 interest and other income, net in the 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.
Reverse Stock Split	'
	Reverse Stock Split
	On May 17, 2013, we effected a 1-for-10 reverse split of our preferred stock and common stock. Upon the effectiveness of the reverse stock split every 10 shares of outstanding preferred stock and common stock was decreased to one share of preferred stock or common stock, as applicable, the number of shares of common stock into which each outstanding option to purchase common stock is exercisable was proportionately decreased on a 1-for-10 basis, and the exercise price of each outstanding option to purchase common stock was proportionately increased on a 1-for-10 basis. All the shares numbers, share prices and exercise prices have been adjusted within the financial statements, on a retroactive basis, to reflect the 1-for-10 reverse stock split.
Net Income (Loss) per Share Attributable to Common Stockholders	'
	Net Income (Loss) per Share Attributable to Common Stockholders
	Basic and diluted net income (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)	12 Months Ended
	Dec. 31, 2013
Revenue Accounted for 10% or More of Total Revenues	'
	Customers that accounted for 10% or more of total revenues were as follows:
		Year Ended December 31,
		2013		2012		2011
	Bristol-Myers Squibb Company and Pfizer Inc.		38%	–		–
	Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		37%	–		–
	Daiichi Sankyo, Inc		23%	–		–
	Novartis, AG	–			97%		12%
	Biogen Idec	–		–			48%
	Merck & Co., Inc.	–		–			40%

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2013
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):
		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
		December 31, 2012
		Level 1			Level 2		Level 3		Total
	Financial Assets:
	Money market funds	$	43,303		$	-	$	-	$	43,303
	Corporate notes and commercial paper		-			64,425		-		64,425
	U.S. government agency securities		-			19,346		-		19,346
	Foreign currency forward contracts		-			51		-		51
	Total financial assets	$	43,303		$	83,822	$	-	$	127,125
	Financial Liabilities:
	Convertible preferred stock warrant liability	$	-		$	-	$	683	$	683
Summary of Changes in Estimated Fair Value	'
	Level 3 liabilities include the convertible preferred stock warrant liability (see Note 10). The following table sets forth a summary of the changes in the estimated fair value of our convertible preferred stock warrants, which were measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2010	$	789
	Recognized gain		(23	)
	Balance as of December 31, 2011		766
	Recognized gain		(83	)
	Balance as of December 31, 2012		683
	Recognized gain		(24	)
	Balance as of December 31, 2013	$	-

Financial_Instruments_Tables

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Cash Equivalents and Investments Classified as Available-for-sale Securities	'
	Cash equivalents and short-term and long-term investments, all of which are classified as available-for-sale securities, consisted of the following (in thousands):
		December 31, 2013									December 31, 2012
									Estimated									Estimated
				Unrealized		Unrealized			Fair				Unrealized		Unrealized			Fair
		Cost		Gain		(Loss)			Value		Cost		Gain		(Loss)			Value
	Money market funds	$	57,296	$	-	$	-		$	57,296	$	43,303	$	-	$	-		$	43,303
	Corporate notes and commercial paper		182,426		62		(16	)		182,472		64,403		25		(3	)		64,425
	U.S. government agency securities		75,278		23		(12	)		75,289		19,335		11		-			19,346
		$	315,000	$	85	$	(28	)	$	315,057	$	127,041	$	36	$	(3	)	$	127,074
	Classified as:
	Cash equivalents								$	113,794								$	43,303
	Short-term investments									150,892									77,656
	Long-term investments									50,371									6,115
	Total cash equivalents and investments								$	315,057								$	127,074

Balance_Sheet_Components_Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2013
Property and Equipment	'
	Property and equipment consists of the following (in thousands):
		December 31,
		2013			2012
	Computer equipment	$	618		$	515
	Capitalized software		463			423
	Equipment		3,690			3,224
	Leasehold improvements		3,988			3,499
			8,759			7,661
	Less accumulated depreciation and amortization		(6,159	)		(4,800	)
	Property and equipment, net	$	2,600		$	2,861
Accrued Expenses	'
	Accrued and other liabilities consist of the following (in thousands):
		December 31,
		2013			2012
	Research and development related	$	16,110		$	4,217
	Legal and accounting fees		462			1,523
	Deferred rent		879			831
	Other		345			828
	Total accrued liabilities	$	17,796		$	7,399

Collaboration_and_License_Agre1

Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2013
Summary of Revenue from Collaboration and License Agreements	'
	We have recognized revenue from our collaboration and license agreements as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Novartis:
	Recognition of upfront license fee	$	-	$	53,846	$	7,692
	Reimbursement of research and development expense		-		16,238		1,879
	Novartis total		-		70,084		9,571
	Merck:
	Recognition of upfront license fee				-		21,429
	Reimbursement of research and development expense		-		-		9,973
	Merck total		-		-		31,402
	Biogen Idec:
	Recognition of upfront license fee		-		-		37,056
	Biogen Idec total		-		-		37,056
	BMS and Pfizer:
	Recognition of research and development services		4,042		1,958		-
	BMS and Pfizer total		4,042		1,958		-
	Bayer and Janssen:
	Recognition of research and development services		3,876		-		-
	Bayer and Janssen total		3,876		-		-
	Lee’s:
	Recognition of research and development services		194		-		-
	Lee’s total		194		-		-
	Daiichi Sankyo:
	Recognition of research and development services		2,419
	Daiichi Sankyo total		2,419		-		-
	Total collaboration and license revenue	$	10,531	$	72,042	$	78,029

Convertible_Preferred_Stock_Wa1

Convertible Preferred Stock Warrant Liability (Tables)	12 Months Ended
	Dec. 31, 2013
Estimated Fair Value for Each of the Convertible Preferred Stock Warrants	'
	Upon closing of the IPO, all convertible preferred stock warrants converted into warrants to purchase shares of common stock at a conversion rate of 1-for-1 and the estimated liability was reclassified to additional paid-in capital. The following table sets forth the estimated fair value for each of the convertible preferred stock warrants as of May 22, 2013, the date of the final remeasurement before reclassifying the liability to APIC, and December 31, 2012 (in thousands, except share and per share data):
								Shares as of		Estimated Fair Value
				Exercise
	Preferred			Price				May 22,	December 31,	May 22,		December 31,
	Stock	Expiration Date		Per Share				2013	2012	2013		2012
	Series A	Later of: (i) January 20, 2015 or (ii) 3 years after the closing of an initial public offering of our common stock		$	10			4,740	4,740	$	35	$	36
	Series B	Later of: (i) September 28, 2016 or (ii) 5 years after the closing of an initial public offering of our common stock		$	13.1			76,335	76,335		624		647
	Total							81,075	81,075	$	659	$	683
Fair Values of Employee Stock Options	'
	The estimated fair value of the above warrants was determined using the Black-Scholes option-pricing model using the following assumptions:
		May 22,				December 31,
		2013				2012
	Risk-free interest rate	0.1 - 0.9%				0.3 - 0.6%
	Estimated term equal to the remaining contractual term	1.7 - 3.8 years				2.1 - 4.2 years
	Volatility		79%				82%
	Dividend yield	–				–

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Future Minimum Commitments Under our Non-Cancelable Operating Leases	'
	At December 31, 2013, our future minimum commitments under our non-cancelable operating leases were as follows (in thousands):
	Year ending December 31:
	2014	$	1,660
	2015		418
	Total	$	2,078

Convertible_Preferred_Stock_an1

Convertible Preferred Stock and Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2013
Outstanding Convertible Preferred Stock	'
	As of December 31, 2013, no shares of convertible preferred stock were outstanding. The authorized, issued, and outstanding shares of convertible preferred stock at December 31, 2012 were as follows:
		Shares		Shares		Carrying
		Authorized		Issued and		Value and
				Outstanding		Liquidation
						Preference
	Series A	43,147,400		4,309,972		$	43,100
	Series B	36,750,400		3,579,597			46,893
	Series C	93,000,000		9,214,160			130,381
	Series D	64,000,000		6,287,026			88,962
	Series 1	6,360,500		636,042			7,944
	Total	243,258,300		24,026,797		$	317,280
Summary of Option Activities	'
	A summary of Portola’s stock option activity follows:
							Shares
							Subject to				Weighted-
			Shares Available				Outstanding				Average Exercise
			for Grant				Options				Price Per Share
	Balance at December 31, 2012			593,011				3,451,178			$	6.35
	Options authorized			150,000			–				–
	Options granted			(1,022,601	)			1,022,601				18.31
	Options exercised		–					(403,468	)			6.4
	Options canceled			361,538				(361,538	)			8.58
	Balance at December 31, 2013			81,948				3,708,773			$	9.43
Additional Information Related to the Status of Options	'
	Additional information related to the status of options at December 31, 2013, is as follows (aggregate intrinsic value in thousands):
							Weighted-
							Average				Remaining
							Exercise Price				Contractual			Aggregate
			Shares				Per Share				Life			Intrinsic Value
	Outstanding and exercisable			3,708,773			$	9.43				6.5		$	60,600
	Vested and expected to vest			3,631,910			$	9.26				6.5		$	60,600
	Vested			2,324,788			$	6.33				5		$	45,199
Stock Options Outstanding and Vested and Exercisable	'
	Additional information regarding our stock options outstanding and vested and exercisable as of December 31, 2013 is summarized below:
			Options Outstanding and Exercisable							Options Vested
			Number of		Weighted
			Options		Average		Weighted			Number		Weighted
			Outstanding		Remaining		Average			of		Average
			and		Contractual		Exercise Price			Options		Exercise Price
	Exercise Prices		Exercisable		Life (Years)		per Share			Vested		Per Share
	$1.00 - $2.00		14,042		1.1		$	1.34		14,042		$	1.34
	$3.30		381,521		2.4			3.3		381,521			3.3
	$3.6 - $4.10		378,399		3.9			4.09		378,399			4.09
	$4.5 - $5.10		463,189		3.6			5.02		463,189			5.02
	$5.30		152,750		4.5			5.3		152,750			5.3
	$7.00		449,244		8.1			7		206,664			7
	$8.50		416,921		7.2			8.5		270,056			8.5
	$9.00		379,318		6.4			9		354,875			9
	$9.5 - $10.90		406,068		9.2			10.05		26,693			9.75
	$19.74 - $28.47		667,321		9.6			22.23		76,599			20.25
			3,708,773		6.5		$	9.43		2,324,788		$	6.33

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Classification of Stock-Based Compensation Expense	'
	Stock-based compensation expense, net of estimated forfeitures, is reflected in the statements of operations as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Research and development	$	2,295		$	1,452		$	1,164
	General and administrative		2,679			1,357			1,189
	Total stock-based compensation	$	4,974		$	2,809		$	2,353
Fair Values of Employee Stock Options	'
	The estimated fair value of the above warrants was determined using the Black-Scholes option-pricing model using the following assumptions:
		May 22,			December 31,
		2013			2012
	Risk-free interest rate	0.1 - 0.9%			0.3 - 0.6%
	Estimated term equal to the remaining contractual term	1.7 - 3.8 years			2.1 - 4.2 years
	Volatility		79%			82%
	Dividend yield	–			–
Stock Option	'
Fair Values of Employee Stock Options	'
	The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of options granted to employees:
		Year Ended December 31,
		2013		2012			2011
	Risk-free interest rate	1.43%		1.10%			1.10%
	Expected life	6.0 years		6.0 years			6.0 years
	Expected volatility	79%		72%			85%
	Dividend yield	–		–			–
Employee Stock Purchase Plan	'
Fair Values of Employee Stock Options	'
	The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of ESPP purchase rights granted to employees:
		Year Ended December 31,
		2013		2012			2011
	Risk-free interest rate	0.10%		–			–
	Expected life	0.42 years		–			–
	Expected volatility	62%		–			–
	Dividend yield	–		–			–

Net_Income_Loss_per_Share_Attr1

Net Income (Loss) per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2013
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 income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Year Ended December 31,
		2013			2012			2011
	Convertible preferred stock	–				24,026,797			24,026,797
	Stock options to purchase common stock		3,708,773			1,653,298			962,225
	Convertible preferred stock warrants	–				81,075			81,075
	Common stock warrants		82,575			1,500			1,500
Computation of Basic and Diluted Net Loss Per Share	'
	The following table sets forth the computation of our basic and diluted net income (loss) per share attributable to common stockholders (in thousands, except share and per share data):
		Year Ended December 31,
		2013			2012			2011
	Net income (loss)	$	(83,352	)	$	11,366		$	19,984
	Noncumulative dividends on convertible preferred stock	–				(11,366	)		(18,757	)
	Undistributed earnings allocated to participating securities	–			–				(1,148	)
	Net income (loss) attributable to common stockholders, basic		(83,352	)		-			79
	Adjustment to undistributed earnings allocated to participating securities	–				-			48
	Net income (loss) attributable to common stockholders, diluted	$	(83,352	)	$	-		$	127
	Shares used in computing net income (loss) per share attributable to common stockholders, basic		22,842,443			1,350,939			1,249,778
	Dilutive effect of common stock options	–				697,928			839,428
	Shares used in computing net income (loss) per share attributable to common stockholders, diluted		22,842,443			2,048,867			2,089,206
	Net income (loss) per share attributable to common stockholders:
	Basic	$	(3.65	)	$	-		$	0.06
	Diluted	$	(3.65	)	$	-		$	0.06

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Reconciliation of Effective Tax Rate for the Provision for Income Taxes	'
	We did not record a tax provision for the years ending December 31, 2013, 2012 and 2011. The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows:
		Year Ended December 31,
		2013			2012			2011
	Federal statutory income tax rate		34	%		34	%		34	%
	State income taxes, net of federal benefit		0.4			22.8			(3.8	)
	Federal and state research credits		3.4			0.8			(5.7	)
	Stock based compensation		(0.2	)		0.4			1.3
	Other		(0.5	)		(0.1	)		0.6
	Change in valuation allowance		(37.1	)		(57.9	)		(26.4	)
			0	%		0	%		0	%
Significant Components of Deferred Tax Assets	'
	Significant components of our deferred tax assets are as follows (in thousands):
		December 31,
		2013			2012
	Deferred tax assets:
	Federal and state net operating loss carryforwards	$	102,478		$	74,390
	Federal and state research tax credit carryforwards		10,750			7,551
	Deferred revenue		1,755			1,434
	Stock options		2,895			2,362
	Capitalized acquisition costs		1,295			1,503
	Other		654			1,859
	Total deferred tax assets		119,827			89,099
	Valuation allowance		(119,827	)		(89,099	)
	Net deferred tax assets	$	-		$	-
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits	'
	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Unrecognized tax benefits, beginning of period	$	1,435		$	1,344		$	973
	Gross increases - current period tax positions		619			91			371
	Gross decreases - tax position in prior period		(6	)		-			-
	Unrecognized tax benefits, end of period	$	2,048		$	1,435		$	1,344

Quarterly_Financial_Data_Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information	'
	The following table presents certain unaudited quarterly financial information. This information has been prepared on the same basis as the audited financial statements and includes all adjustments (consisting only of normal recurring adjustments) necessary to present fairly the unaudited quarterly results of operations set forth herein. Net income (loss) per share for all periods presented have been retroactively adjusted to reflect the 1-for-10 reverse stock split effected on May 17, 2013. All data is in thousands except per share data.
		2013												2012
		Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
	Collaboration and license revenue	$	3,108		$	2,601		$	2,766		$	2,056		$	2,481		$	66,865		$	738		$	1,958
	Operating expenses	$	(20,761	)	$	(24,541	)	$	(21,995	)	$	(27,412	)	$	(15,768	)	$	(16,147	)	$	(12,833	)	$	(16,438	)
	Net income (loss)	$	(18,142	)	$	(21,598	)	$	(18,550	)	$	(25,062	)	$	(13,127	)	$	49,762		$	(11,488	)	$	(13,781	)
	Net income (loss) per share:
	Basic	$	(12.94	)	$	(1.47	)	$	(0.53	)	$	(0.63	)	$	(10.08	)	$	1.71		$	(8.38	)	$	(10.02	)
	Diluted	$	(12.94	)	$	(1.47	)	$	(0.53	)	$	(0.63	)	$	(10.08	)	$	1.67		$	(8.38	)	$	(10.02	)

Organization_Additional_Inform

Organization - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended		1 Months Ended
	Nov. 30, 2013	31-May-13	Dec. 31, 2013	Oct. 31, 2013	Nov. 30, 2013	Oct. 31, 2013	Nov. 30, 2013	31-May-13
			Segment		Follow-on Offering	Follow-on Offering	Underwriters Overallotment Option	Underwriters Overallotment Option
Organization And Nature Of Business [Line Items]	'	'	'	'	'	'	'	'
Number of operating segment	'	'	1	'	'	'	'	'
Stock issued during the period	'	9,686,171	'	'	'	6,366,513	954,976	1,263,413
Public offering price of the shares sold	'	$14.50	'	'	'	'	'	'
Proceeds from initial public offering before offering costs	'	$131,000,000	'	'	'	'	'	'
Underwriting discounts and commissions	'	9,400,000	'	'	'	'	'	'
Offering expenses	'	5,200,000	'	'	862,000	'	'	'
Proceeds from initial public offering, net of underwriters discount	'	125,800,000	251,865,000	'	'	'	'	'
Number of preferred stock converted into common stock	'	24,026,797	24,026,797	'	'	'	'	'
Stock Issued during period shares existing shareholder	'	'	'	'	'	1,908,803	'	'
Follow on offering price per share	'	'	'	$23.75	'	'	'	'
Proceeds from offering and over-allotment option, gross	120,800,000	'	'	'	'	'	'	'
Underwriting discounts and commissions, net	'	'	'	'	7,700,000	'	'	'
Proceeds from offering and over-allotment option, net	$119,900,000	'	'	'	'	'	'	'

Revenue_Accounted_for_10_or_Mo

Revenue Accounted for 10% or More of Total Revenues (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2011
	Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Daiichi Sankyo, Inc ("Daiichi")	Novartis AG ("Novartis")	Novartis AG ("Novartis")	Biogen Idec	Merck & Co., Inc.
Concentration Risk [Line Items]	'	'	'	'	'	'	'
Percentage of major customers revenue accounted for 10% or more of total revenues	38.00%	37.00%	23.00%	97.00%	12.00%	48.00%	40.00%

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended
In Millions, except Share data, unless otherwise specified	17-May-13	31-May-13	Dec. 31, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Deferred offering costs capitalized	'	'	'	$1.60
Number of preferred stock converted into common stock	'	24,026,797	24,026,797	'
Reverse stock split ratio on preferred and common stock	0.1	'	'	'
IPO	'	'	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Deferred offering costs capitalized	'	'	$0	'
Minimum	'	'	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Property and equipment useful lives	'	'	'2 years	'
Maximum	'	'	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Property and equipment useful lives	'	'	'5 years	'

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 $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Financial Assets:	'	'
Total financial assets	$315,429	$127,125
Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Total financial assets	57,296	43,303
Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Total financial assets	258,133	83,822
Fair Value, Inputs, Level 3	'	'
Financial Assets:	'	'
Total financial assets	'	'
Money market funds	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	57,296	43,303
Money market funds | Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	57,296	43,303
Money market funds | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
Money market funds | Fair Value, Inputs, Level 3	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
Corporate notes and commercial paper	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	182,472	64,425
Corporate notes and commercial paper | Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
Corporate notes and commercial paper | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	182,472	64,425
Corporate notes and commercial paper | Fair Value, Inputs, Level 3	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
U.S. government agency securities	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	75,289	19,346
U.S. government agency securities | Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
U.S. government agency securities | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	75,289	19,346
U.S. government agency securities | Fair Value, Inputs, Level 3	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
Foreign currency forward contracts	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	372	51
Foreign currency forward contracts | Fair Value, Inputs, Level 1	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
Foreign currency forward contracts | Fair Value, Inputs, Level 2	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	372	51
Foreign currency forward contracts | Fair Value, Inputs, Level 3	'	'
Financial Assets:	'	'
Fair value of financial assets measured on a recurring basis	'	'
Convertible Preferred Stock	'	'
Financial Liabilities:	'	'
Fair value of financial liabilities measured on a recurring basis	'	683
Convertible Preferred Stock | Fair Value, Inputs, Level 1	'	'
Financial Liabilities:	'	'
Fair value of financial liabilities measured on a recurring basis	'	'
Convertible Preferred Stock | Fair Value, Inputs, Level 2	'	'
Financial Liabilities:	'	'
Fair value of financial liabilities measured on a recurring basis	'	'
Convertible Preferred Stock | Fair Value, Inputs, Level 3	'	'
Financial Liabilities:	'	'
Fair value of financial liabilities measured on a recurring basis	'	$683

Summary_of_Changes_in_Estimate

Summary of Changes in Estimated Fair Value (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Inputs Assets Quantitative Information [Line Items]	'	'	'
Beginning balance	$683	$766	$789
Recognized gain	-24	-83	-23
Ending balance	'	$683	$766

Cash_Equivalents_and_Investmen

Cash Equivalents and Investments Classified as Available-for-sale Securities (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	$315,000	$127,041
Unrealized Gain	85	36
Unrealized (Loss)	-28	-3
Estimated Fair Value	315,057	127,074
Money market funds	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	57,296	43,303
Unrealized Gain	'	'
Unrealized (Loss)	'	'
Estimated Fair Value	57,296	43,303
Corporate notes and commercial paper	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	182,426	64,403
Unrealized Gain	62	25
Unrealized (Loss)	-16	-3
Estimated Fair Value	182,472	64,425
U.S. government agency securities	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Cost	75,278	19,335
Unrealized Gain	23	11
Unrealized (Loss)	-12	'
Estimated Fair Value	75,289	19,346
Cash equivalents	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Estimated Fair Value	113,794	43,303
Short-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Estimated Fair Value	150,892	77,656
Long-term investments	'	'
Schedule Of Available For Sale Securities [Line Items]	'	'
Estimated Fair Value	$50,371	$6,115

Financial_Instruments_Addition

Financial Instruments - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]	'
Available-for-sale securities remaining contractual maturities	'2 years
Available-for-sale Securities, Gross Realized Gain (Loss)	$0

Derivative_Instruments_Additio

Derivative Instruments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012
	USD ($)	USD ($)	EUR (€)	EUR (€)	Prepaid Expenses and Other Current Assets	Prepaid Expenses and Other Current Assets	Other Long Lived Assets
					USD ($)	USD ($)	USD ($)
Derivatives Fair Value [Line Items]	'	'	'	'	'	'	'
Foreign currency forward contracts, notional amount	$10,600,000	$22,200,000	€ 7,700,000	€ 16,800,000	'	'	'
Derivative assets	'	'	'	'	372,000	30,000	21,000
Foreign currency forward contracts unrealized gain (loss)	261,000	51,000	'	'	'	'	'
Foreign currency forward contracts realized gain (loss)	$60,000	$0	'	'	'	'	'

Property_and_Equipment_Detail

Property and Equipment (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property Plant And Equipment [Line Items]	'	'
Property and equipment, gross	$8,759	$7,661
Less accumulated depreciation and amortization	-6,159	-4,800
Property and equipment, net	2,600	2,861
Computer equipment	'	'
Property Plant And Equipment [Line Items]	'	'
Property and equipment, gross	618	515
Capitalized software	'	'
Property Plant And Equipment [Line Items]	'	'
Property and equipment, gross	463	423
Equipment	'	'
Property Plant And Equipment [Line Items]	'	'
Property and equipment, gross	3,690	3,224
Leasehold improvements	'	'
Property Plant And Equipment [Line Items]	'	'
Property and equipment, gross	$3,988	$3,499

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	31-May-10
In Thousands, unless otherwise specified
Accounts Payable And Accrued Liabilities [Line Items]	'	'	'
Research and development related	$16,110	$4,217	'
Legal and accounting fees	462	1,523	'
Deferred rent	879	831	3,200
Other	345	828	'
Total accrued liabilities	$17,796	$7,399	'

Summary_of_Revenue_from_Collab

Summary of Revenue from Collaboration and License Agreements (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	$2,056	$2,766	$2,601	$3,108	$1,958	$738	$66,865	$2,481	$10,531	$72,042	$78,029
Novartis AG ("Novartis")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	0	70,084	9,571
Merck & Co., Inc.	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	0	'	31,402
Biogen Idec	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	0	'	37,056
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	4,042	1,958	'
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	3,876	'	'
Lee’s Pharmaceutical (HK) Ltd (“Lee’s”)	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	194	'	'
Daiichi Sankyo, Inc ("Daiichi")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	2,419	'	'
Licensing Agreements | Novartis AG ("Novartis")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	0	53,846	7,692
Reimbursement of research and development expense	'	'	'	'	'	'	'	'	0	16,238	1,879
Licensing Agreements | Merck & Co., Inc.	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	'	'	21,429
Reimbursement of research and development expense	'	'	'	'	'	'	'	'	0	'	9,973
Licensing Agreements | Biogen Idec	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	0	'	37,056
Licensing Agreements | Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	4,042	1,958	'
Licensing Agreements | Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	3,876	'	'
Licensing Agreements | Lee’s Pharmaceutical (HK) Ltd (“Lee’s”)	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	194	'	'
Licensing Agreements | Daiichi Sankyo, Inc ("Daiichi")	'	'	'	'	'	'	'	'	'	'	'
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	'	'	'	'	'	'	'	'	$2,419	'	'

Collaboration_and_License_Agre2

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

1 Months Ended

3 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

31-May-13

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Apr. 30, 2012

Feb. 28, 2009

Apr. 30, 2012

Aug. 31, 2009

Jul. 31, 2009

Nov. 30, 2012

Oct. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Oct. 31, 2011

Oct. 31, 2011

Oct. 31, 2011

Oct. 31, 2011

Oct. 31, 2011

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Jan. 31, 2013

Dec. 31, 2013

Feb. 01, 2013

Feb. 01, 2013

Feb. 01, 2013

Dec. 31, 2013

Dec. 31, 2013

Jun. 30, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Novartis AG ("Novartis")

Novartis AG ("Novartis")

Novartis AG ("Novartis")

Merck & Co., Inc. (“Merck”)

Merck & Co., Inc. (“Merck”)

Biogen Idec

Biogen Idec

Biogen Idec

Biogen Idec

Biogen Idec

Biogen Idec

Biogen Idec

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")

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

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

Bayer Pharma, AG (“Bayer”)

Janssen Pharmaceuticals, Inc. (“Janssen”)

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

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

Aciex Therapeutics, Inc. (“Aciex”)

Daiichi Sankyo, Inc ("Daiichi")

Daiichi Sankyo, Inc ("Daiichi")

Daiichi Sankyo, Inc ("Daiichi")

PORTOLA PHARMACEUTICALS INC

Absent Collaboration Revenue Acceleration

Phase 2 Clinical Trial

Phase 3 Clinical Trial

Milestone One

Milestone Two

Convertible Preferred Stock

Collaborative Arrangement

Under Previous Accounting Guidance for Multiple Element Arrangements

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

Collaborative Arrangement

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Upfront and non-refundable fee

'

'

'

'

'

'

'

'

'

'

'

'

'

$75,000,000

'

$50,000,000

'

'

$36,000,000

'

'

'

'

'

'

'

'

'

'

'

'

$700,000

'

$2,500,000

$2,500,000

$5,000,000

'

'

'

'

'

'

License fee receivable upon occurrence of certain development and regulatory events

'

'

'

'

'

'

'

'

'

'

'

'

'

505,000,000

'

'

420,000,000

370,000,000

508,500,000

'

'

23,000,000

485,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Clinical trial costs company must fund

'

'

'

'

'

'

'

'

'

'

'

'

'

18,000,000

'

'

'

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Increase in collaborative revenue

'

'

'

'

'

'

'

'

'

1,169,000

-65,426,000

-35,387,000

65,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Impact of scenario on net income

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-65,100,000

'

'

'

'

'

'

'

'

'

'

'

'

3,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net income (loss)

'

-25,062,000

-18,550,000

-21,598,000

-18,142,000

-13,781,000

-11,488,000

49,762,000

-13,127,000

-83,352,000

11,366,000

19,984,000

'

'

53,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net income (loss) per share

'

'

'

'

'

'

'

'

'

'

'

'

$0

'

($3.98)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Sale of stock, value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock issued during the period

9,686,171

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

636,042

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Premium on sale of stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated partial reimbursement of research and development services

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

22,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

36,000,000

22,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000,000

581,000

'

Collaboration revenue recognized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

37,100,000

'

'

4,000,000

2,000,000

'

194,000

'

'

'

3,900,000

'

'

'

2,400,000

'

Reduction in research and development expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

804,000

6,500,000

'

'

'

'

'

734,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Performance period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'2 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notice period for agreement termination

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'120 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'60 days

'

'

'

'

'

'

'

'

'

'

Deferred revenue

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,000,000

'

'

'

506,000

'

'

'

1,100,000

'

'

'

'

'

Additional non-refundable fee

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

250,000

250,000

500,000

'

'

'

'

'

'

Development costs, percent

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

40.00%

Research and development

'

'

'

'

'

'

'

'

'

79,286,000

49,717,000

46,089,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

Collaborative arrangement upfront payment to be received

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,000,000

'

'

'

Upfront fee subject to refund

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000,000

'

'

'

Contingent consideration to be recognized after resolution of contingency

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,000,000

'

'

Contingent consideration of collaboration arrangement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3,000,000

'

Asset_Acquisition_and_License_1

Asset Acquisition and License Agreements - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended			1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 30, 2007	Dec. 31, 2009	Dec. 31, 2009	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2008	Dec. 31, 2013	Dec. 31, 2013
				Millennium	Millennium	Millennium	Millennium	Astellas Pharma Inc	Astellas Pharma Inc	Astellas Pharma Inc	Astellas Pharma Inc
						Series C Convertible Preferred Stock	Maximum				Maximum
Asset Acquisition [Line Items]	'	'	'	'	'	'	'	'	'	'	'
License fees paid	'	'	'	$5,000,000	$250,000	'	'	$7,200,000	$1,000,000	'	'
Research and development	79,286,000	49,717,000	46,089,000	5,000,000	'	250,000	'	7,200,000	'	'	'
Additional license fees payable on occurrence of specified events	'	'	'	'	'	'	$35,000,000	'	'	'	$71,500,000
Convertible preferred stock, shares issued as payment	'	'	'	'	'	17,667	'	'	'	'	'
Issuance of convertible preferred stock, price per share	'	'	'	'	'	$14.15	'	'	'	'	'
Percentage required to pay for any payment received under collaboration excluding royalties	'	'	'	'	'	'	'	'	'	20.00%	'

Restructuring_Charge_Additiona

Restructuring Charge - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended	14 Months Ended
	Apr. 30, 2013	Jan. 31, 2013	Nov. 30, 2012	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
	Employee	Employee	Employee	Employee
Restructuring Cost And Reserve [Line Items]	'	'	'	'	'	'
Number of employees terminated	2	5	16	23	'	'
Net restructuring charge	'	'	'	$79,000	$698,000	'
Payment of Severance cost	'	'	'	223,000	'	'
Accrued restructuring liability	'	'	'	0	0	143,000
Research and Development Expense	'	'	'	'	'	'
Restructuring Cost And Reserve [Line Items]	'	'	'	'	'	'
Net restructuring charge	'	'	'	66,000	'	'
General and Administrative Expense	'	'	'	'	'	'
Restructuring Cost And Reserve [Line Items]	'	'	'	'	'	'
Net restructuring charge	'	'	'	$13,000	'	'

Estimated_Fair_Value_for_Each_

Estimated Fair Value for Each of the Convertible Preferred Stock Warrants (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	22-May-13	Dec. 31, 2012
Convertible Preferred Stock Warrants [Line Items]	'	'	'
Shares	'	81,075	81,075
Estimated Fair Value	'	$659	$683
Series A Preferred Stock	'	'	'
Convertible Preferred Stock Warrants [Line Items]	'	'	'
Expiration Date	'Later of: (i) January 20, 2015 or (ii) 3 years after the closing of an initial public offering of our common stock	'	'
Exercise Price Per Share	10	'	'
Shares	'	4,740	4,740
Estimated Fair Value	'	35	36
Series B Preferred Stock	'	'	'
Convertible Preferred Stock Warrants [Line Items]	'	'	'
Expiration Date	'Later of: (i) September 28, 2016 or (ii) 5 years after the closing of an initial public offering of our common stock	'	'
Exercise Price Per Share	13.1	'	'
Shares	'	76,335	76,335
Estimated Fair Value	'	$624	$647

Estimated_Fair_Value_of_Conver

Estimated Fair Value of Convertible Preferred Stock Warrant Determined Using Black-Sholes Option Pricing Mode (Detail)	5 Months Ended	12 Months Ended
	22-May-13	Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'
Volatility	79.00%	82.00%
Dividend yield	'	'
Minimum	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'
Risk-free interest rate	0.10%	0.30%
Estimated term equal to the remaining contractual term	'1 year 8 months 12 days	'2 years 1 month 6 days
Maximum	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'
Risk-free interest rate	0.90%	0.60%
Estimated term equal to the remaining contractual term	'3 years 9 months 18 days	'4 years 2 months 12 days

Convertible_Preferred_Stock_Wa2

Convertible Preferred Stock Warrant Liability - Additional Information (Detail)	Dec. 31, 2013
Convertible Preferred Stock Warrants [Line Items]	'
Warrant conversion rate	1

Future_Minimum_Commitments_Und

Future Minimum Commitments Under our Non-Cancelable Operating Leases (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule Of Operating Leases [Line Items]	'
2014	$1,660
2015	418
Total	$2,078

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	31-May-10	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commitments And Contingencies [Line Items]	'	'	'	'
Lease cancellation notice period	'	'30 days	'	'
Commitment to payment for services performed in next fiscal year	'	$5,200,000	'	'
Tenant improvement allowance	3,200,000	879,000	831,000	'
Term of optional lease extension	'3 years	'	'	'
Rent expense	'	$803,000	$800,000	$1,000,000

Outstanding_Convertible_Prefer

Outstanding Convertible Preferred Stock (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Class Of Stock [Line Items]	'	'
Shares Authorized	0	243,258,300
Shares Issued	0	24,026,797
Shares Outstanding	0	24,026,797
Carrying Value	'	$317,280
Liquidation Preference	'	317,280
Series A Preferred Stock	'	'
Class Of Stock [Line Items]	'	'
Shares Authorized	'	43,147,400
Shares Issued	'	4,309,972
Shares Outstanding	'	4,309,972
Carrying Value	'	43,100
Liquidation Preference	'	43,100
Series B Preferred Stock	'	'
Class Of Stock [Line Items]	'	'
Shares Authorized	'	36,750,400
Shares Issued	'	3,579,597
Shares Outstanding	'	3,579,597
Carrying Value	'	46,893
Liquidation Preference	'	46,893
Series C Preferred Stock	'	'
Class Of Stock [Line Items]	'	'
Shares Authorized	'	93,000,000
Shares Issued	'	9,214,160
Shares Outstanding	'	9,214,160
Carrying Value	'	130,381
Liquidation Preference	'	130,381
Series D Preferred Stock	'	'
Class Of Stock [Line Items]	'	'
Shares Authorized	'	64,000,000
Shares Issued	'	6,287,026
Shares Outstanding	'	6,287,026
Carrying Value	'	88,962
Liquidation Preference	'	88,962
Series 1 Preferred Stock	'	'
Class Of Stock [Line Items]	'	'
Shares Authorized	'	6,360,500
Shares Issued	'	636,042
Shares Outstanding	'	636,042
Carrying Value	'	7,944
Liquidation Preference	'	$7,944

Summary_of_Stock_Option_Activi

Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Shares Available for Grant	'
Beginning balance	593,011
Options authorized	150,000
Options granted	-1,022,601
Options canceled	361,538
Ending balance	81,948
Shares Subject to Outstanding Options	'
Beginning balance	3,451,178
Options granted	1,022,601
Options exercised	-403,468
Options canceled	-361,538
Ending balance	3,708,773
Weighted-Average Exercise Price Per Share	'
Beginning balance	$6.35
Options granted	$18.31
Options exercised	$6.40
Options cancelled	$8.58
Ending balance	$9.43

Status_of_Options_Detail

Status of Options (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013
Shares	'
Outstanding and exercisable	3,708,773
Vested and expected to vest	3,631,910
Vested	2,324,788
Weighted-Average Exercise Price Per Share	'
Outstanding and exercisable	$9.43
Vested and expected to vest	$9.26
Vested	$6.33
Remaining Contractual Life	'
Outstanding and exercisable	'6 years 6 months
Vested and expected to vest	'6 years 6 months
Vested	'5 years
Aggregate Intrinsic Value	'
Outstanding and exercisable	$60,600
Vested and expected to vest	60,600
Vested	$45,199

Stock_Options_Outstanding_and_

Stock Options Outstanding and Vested and Exercisable (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	3,708,773
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'6 years 6 months
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$9.43
Options Vested, Number of Options Vested	2,324,788
Options Vested, Weighted Average Exercise Price Per Share	$6.33
$1.00 - $2.00	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices, Lower Limit	$1
Exercise Prices, Upper Limit	$2
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	14,042
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'1 year 1 month 6 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$1.34
Options Vested, Number of Options Vested	14,042
Options Vested, Weighted Average Exercise Price Per Share	$1.34
$3.30	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices	$3.30
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	381,521
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'2 years 4 months 24 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$3.30
Options Vested, Number of Options Vested	381,521
Options Vested, Weighted Average Exercise Price Per Share	$3.30
$3.6 - $4.10	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices, Lower Limit	$3.60
Exercise Prices, Upper Limit	$4.10
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	378,399
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'3 years 10 months 24 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$4.09
Options Vested, Number of Options Vested	378,399
Options Vested, Weighted Average Exercise Price Per Share	$4.09
$4.5 - $5.10	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices, Lower Limit	$4.50
Exercise Prices, Upper Limit	$5.10
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	463,189
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'3 years 7 months 6 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$5.02
Options Vested, Number of Options Vested	463,189
Options Vested, Weighted Average Exercise Price Per Share	$5.02
$5.30	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices	$5.30
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	152,750
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'4 years 6 months
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$5.30
Options Vested, Number of Options Vested	152,750
Options Vested, Weighted Average Exercise Price Per Share	$5.30
$7.00	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices	$7
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	449,244
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'8 years 1 month 6 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$7
Options Vested, Number of Options Vested	206,664
Options Vested, Weighted Average Exercise Price Per Share	$7
$8.50	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices	$8.50
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	416,921
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'7 years 2 months 12 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$8.50
Options Vested, Number of Options Vested	270,056
Options Vested, Weighted Average Exercise Price Per Share	$8.50
$9.00	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices	$9
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	379,318
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'6 years 4 months 24 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$9
Options Vested, Number of Options Vested	354,875
Options Vested, Weighted Average Exercise Price Per Share	$9
$9.5 - $10.90	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices, Lower Limit	$9.50
Exercise Prices, Upper Limit	$10.90
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	406,068
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'9 years 2 months 12 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$10.05
Options Vested, Number of Options Vested	26,693
Options Vested, Weighted Average Exercise Price Per Share	$9.75
$19.74 - $28.47	'
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]	'
Exercise Prices, Lower Limit	$19.74
Exercise Prices, Upper Limit	$28.47
Options Outstanding and Exercisable, Number of Options Outstanding and Exercisable	667,321
Options Outstanding and Exercisable, Weighted Average Remaining Contractual Life (Years)	'9 years 7 months 6 days
Options Outstanding and Exercisable, Weighted Average Exercise Price per Share	$22.23
Options Vested, Number of Options Vested	76,599
Options Vested, Weighted Average Exercise Price Per Share	$20.25

Convertible_Preferred_Stock_an2

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	22-May-13
Class Of Stock [Line Items]	'	'	'	'
Convertible preferred stock, shares outstanding	0	24,026,797	'	'
Cash dividend annual rate	8.00%	'	'	'
Warrants to purchase share of common stock were outstanding at exercise price	'	81,075	'	81,075
Term of stock options granted	'10 years	'	'	'
Vesting period of stock options	'4 years	'	'	'
Common stock reserved, shares	81,948	'	'	'
Number of common stock shares reserved for issuance under the 2013 Employee Stock Purchase Plan	4,903,323	'	'	'
Aggregate intrinsic value of options exercised	$6,300,000	$451,000	$290,000	'
Total estimated grant date fair value of options vested	$3,800,000	$3,000,000	$1,800,000	'
Preferred stock, shares authorized	5,000,000	0	'	'
Incentive Stock Options	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Exercise price of stock options granted as a minimum percentage of fair value of common stock	100.00%	'	'	'
Nonstatutory Stock Options	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Exercise price of stock options granted as a minimum percentage of fair value of common stock	85.00%	'	'	'
10% or more	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Exercise price of stock options granted as a minimum percentage of fair value of common stock	110.00%	'	'	'
Percentage of voting stock	10.00%	'	'	'
Warrant	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Warrants to purchase share of common stock were outstanding at exercise price	82,575	'	'	'
Minimum | Warrant	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Exercise Price Per Share	10	'	'	'
Maximum | Warrant	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Exercise Price Per Share	13.1	'	'	'
Series D Preferred Stock	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Convertible preferred stock, shares outstanding	'	6,287,026	'	'
Number of votes per common stock the preferred stock converts into	1	'	'	'
Original issue price of stock	$14.15	'	'	'
Series D Preferred Stock | Minimum	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Percentage of outstanding convertible preferred stock	50.00%	'	'	'
Series 1 Preferred Stock	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Convertible preferred stock, shares outstanding	'	636,042	'	'
Number of votes per common stock the preferred stock converts into	0	'	'	'
Original issue price of stock	$14.15	'	'	'
Series A Preferred Stock	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Convertible preferred stock, shares outstanding	'	4,309,972	'	'
Number of votes per common stock the preferred stock converts into	1	'	'	'
Original issue price of stock	$10	'	'	'
Warrants to purchase share of common stock were outstanding at exercise price	'	4,740	'	4,740
Exercise Price Per Share	10	'	'	'
Series B Preferred Stock	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Convertible preferred stock, shares outstanding	'	3,579,597	'	'
Number of votes per common stock the preferred stock converts into	1	'	'	'
Original issue price of stock	$13.10	'	'	'
Warrants to purchase share of common stock were outstanding at exercise price	'	76,335	'	76,335
Exercise Price Per Share	13.1	'	'	'
Series C Preferred Stock	'	'	'	'
Class Of Stock [Line Items]	'	'	'	'
Convertible preferred stock, shares outstanding	'	9,214,160	'	'
Number of votes per common stock the preferred stock converts into	1	'	'	'
Original issue price of stock	$14.15	'	'	'

Classification_of_StockBased_C

Classification of Stock-Based Compensation Expense (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation	$4,974,000	$2,809,000	$2,353,000
Research and Development Expense	'	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation	2,295,000	1,452,000	1,164,000
General and Administrative Expense	'	'	'
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation	$2,679,000	$1,357,000	$1,189,000

Fair_Values_of_Employee_Stock_

Fair Values of Employee Stock Options (Detail) (Stock Option)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Option	'	'	'
Share Based Compensation Arrangement Assumptions Used To Estimate Fair Values Of Share Options Granted [Line Items]	'	'	'
Risk-free interest rate	1.43%	1.10%	1.10%
Expected life	'6 years	'6 years	'6 years
Expected volatility	79.00%	72.00%	85.00%
Dividend yield	'	'	'

Fair_Value_of_ESPP_Purchase_Ri

Fair Value of ESPP Purchase Rights Granted (Detail) (Employee Stock Purchase Plan)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Stock Purchase Plan	'	'	'
Share Based Compensation Arrangement Assumptions Used To Estimate Fair Values Of Share Options Granted [Line Items]	'	'	'
Risk-free interest rate	0.10%	'	'
Expected life	'5 months 1 day	'	'
Expected volatility	62.00%	'	'
Dividend yield	'	'	'

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]	'	'	'
Unamortized share based compensation expected to be recognized over the remaining vesting period	$12,500,000	'	'
Unamortized share based compensation period for recognition	'2 years 9 months 18 days	'	'
Weighted-average per share fair value of employee options granted	$12.46	$5.90	$4.70
Share based compensation, options weighted average exercise price	$18.31	'	'
Vesting period of stock options	'4 years	'	'
Stock-based compensation	4,974,000	2,809,000	2,353,000
Number of common stock shares reserved for issuance under the 2013 Employee Stock Purchase Plan	4,903,323	'	'
Nonemployee Stock Options	'	'	'
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]	'	'	'
Share based compensation, options granted	32,943	6,380	'
Share based compensation, options weighted average exercise price	$19.88	$7	'
Vesting period of stock options	'4 years	'	'
Stock-based compensation	$775,000	$144,000	$65,000
Employee Stock Purchase Plan	'	'	'
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]	'	'	'
Number of common stock shares reserved for issuance under the 2013 Employee Stock Purchase Plan	1,000,000	'	'
Percentage of common stock to employees at lesser of fair market value	85.00%	'	'
Percentage increase in number of common stock outstanding	2.00%	'	'

Outstanding_Shares_of_Common_S

Outstanding Shares of Common Stock Excluded from Computation of Diluted Net Loss per Share (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
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	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	3,708,773	1,653,298	962,225
Convertible 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	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	82,575	1,500	1,500

Computation_of_Basic_and_Dilut

Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Earnings Per Share Basic And Diluted [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Net income (loss)	($25,062)	($18,550)	($21,598)	($18,142)	($13,781)	($11,488)	$49,762	($13,127)	($83,352)	$11,366	$19,984
Noncumulative dividends on convertible preferred stock	'	'	'	'	'	'	'	'	'	-11,366	-18,757
Undistributed earnings allocated to participating securities	'	'	'	'	'	'	'	'	'	'	-1,148
Net income (loss) attributable to common stockholders, basic	'	'	'	'	'	'	'	'	-83,352	'	79
Adjustment to undistributed earnings allocated to participating securities	'	'	'	'	'	'	'	'	'	'	48
Net income (loss) attributable to common stockholders, diluted	'	'	'	'	'	'	'	'	($83,352)	'	$127
Shares used to compute net income (loss) per share attributable to common stockholders:	'	'	'	'	'	'	'	'	'	'	'
Weighted average common shares outstanding	'	'	'	'	'	'	'	'	22,842,443	1,350,939	1,249,778
Weighted average effect of dilutive stock options	'	'	'	'	'	'	'	'	'	697,928	839,428
Weighted average number of shares outstanding, diluted shares	'	'	'	'	'	'	'	'	22,842,443	2,048,867	2,089,206
Net income (loss) per share attributable to common stockholders:	'	'	'	'	'	'	'	'	'	'	'
Basic	($0.63)	($0.53)	($1.47)	($12.94)	($10.02)	($8.38)	$1.71	($10.08)	($3.65)	'	$0.06
Diluted	($0.63)	($0.53)	($1.47)	($12.94)	($10.02)	($8.38)	$1.67	($10.08)	($3.65)	'	$0.06

Employee_Benefit_Plan_Addition

Employee Benefit Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Contribution Plan [Line Items]	'	'	'
Defined contribution plan maximum annual employer matching contribution per employee	$500	$500	$500
Employee benefit plans, contribution expense	$59,000	$31,000	$35,000

Reconciliation_of_Effective_Ta

Reconciliation of Effective Tax Rate for the Provision for Income Taxes (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Effective Tax Rate Reconciliation [Line Items]	'	'	'
Federal statutory income tax rate	34.00%	34.00%	34.00%
State income taxes, net of federal benefit	0.40%	22.80%	-3.80%
Federal and state research credits	3.40%	0.80%	-5.70%
Stock based compensation	-0.20%	0.40%	1.30%
Other	-0.50%	-0.10%	0.60%
Change in valuation allowance	-37.10%	-57.90%	-26.40%
Effective income tax rate	0.00%	0.00%	0.00%

Significant_Components_of_Defe

Significant Components of Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred tax assets:	'	'
Federal and state net operating loss carryforwards	$102,478	$74,390
Federal and state research tax credit carryforwards	10,750	7,551
Deferred revenue	1,755	1,434
Stock options	2,895	2,362
Capitalized acquisition costs	1,295	1,503
Other	654	1,859
Total deferred tax assets	119,827	89,099
Valuation allowance	-119,827	-89,099
Net deferred tax assets	'	'

Reconciliation_of_the_Beginnin

Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation Of Unrecognized Tax Benefits [Line Items]	'	'	'
Unrecognized tax benefits, beginning of period	$1,435	$1,344	$973
Gross increases - current period tax positions	619	91	371
Gross decreases - tax position in prior period	-6	'	'
Unrecognized tax benefits, end of period	$2,048	$1,435	$1,344

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax [Line Items]	'	'	'	'
Increase (Decrease) in valuation allowance	$30,700,000	($6,800,000)	'	'
Unrecognized income tax benefits that, if recognized, would affect effective tax rate	365,000	365,000	'	'
Unrecognized income tax benefits	2,048,000	1,435,000	1,344,000	973,000
Minimum	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Tax years remain open to examinations	'2003	'	'	'
Maximum	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Tax years remain open to examinations	'2013	'	'	'
Federal	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Net operating loss carryforwards	260,000,000	'	'	'
Federal | Research Tax Credit Carryforward	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Tax credits carryforwards	10,900,000	'	'	'
Federal | Research Tax Credit Carryforward | Minimum	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Federal research tax credits, expiration year	'2023	'	'	'
Federal | Research Tax Credit Carryforward | Maximum	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Federal research tax credits, expiration year	'2033	'	'	'
State	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Net operating loss carryforwards	227,600,000	'	'	'
State | Minimum	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Net operating loss carryforwards, expiration year	'2014	'	'	'
State | Maximum	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Net operating loss carryforwards, expiration year	'2033	'	'	'
State | Research Tax Credit Carryforward	'	'	'	'
Income Tax [Line Items]	'	'	'	'
Tax credits carryforwards	$2,400,000	'	'	'

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]	'	'
Receivables from related parties	$394,000	$57,000
Master Services Agreement	'	'
Related Party Transaction [Line Items]	'	'
Reduction in research and development expense	$816,000	$57,000

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)

3 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Jan. 31, 2014

Dec. 31, 2013

Jan. 31, 2014

Jan. 31, 2014

Jan. 31, 2014

Jan. 31, 2014

Jan. 31, 2014

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")

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

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

Upfront Payment

Upfront Payment

Milestone Payment

Milestone Payment

Subsequent Event

Subsequent Event

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

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

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

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

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event

Subsequent Event [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Consideration on agreement

$2,056

$2,766

$2,601

$3,108

$1,958

$738

$66,865

$2,481

$10,531

$72,042

$78,029

$4,042

$1,958

$25,000

$3,876

$25,000

$13,000

$10,000

$12,000

$15,000

Quarterly_Financial_Informatio

Quarterly Financial Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration and license revenue	$2,056	$2,766	$2,601	$3,108	$1,958	$738	$66,865	$2,481	$10,531	$72,042	$78,029
Operating expenses	-27,412	-21,995	-24,541	-20,761	-16,438	-12,833	-16,147	-15,768	-94,709	-61,186	-58,160
Net income (loss)	($25,062)	($18,550)	($21,598)	($18,142)	($13,781)	($11,488)	$49,762	($13,127)	($83,352)	$11,366	$19,984
Net income (loss) per share:	'	'	'	'	'	'	'	'	'	'	'
Basic	($0.63)	($0.53)	($1.47)	($12.94)	($10.02)	($8.38)	$1.71	($10.08)	($3.65)	'	$0.06
Diluted	($0.63)	($0.53)	($1.47)	($12.94)	($10.02)	($8.38)	$1.67	($10.08)	($3.65)	'	$0.06

Quarterly_Financial_Data_Addit

Quarterly Financial Data - Additional Information (Detail)	1 Months Ended
	17-May-13
Conversion Of Stock [Line Items]	'
Reverse stock split ratio on preferred and common stock	0.1