Collaboration and License Agreements - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended						6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Apr. 30, 2014	Nov. 30, 2012	Jan. 31, 2014	Jan. 31, 2013	Feb. 28, 2013	Jul. 31, 2014	Jun. 30, 2013
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	$ 2,359,000	$ 2,372,000
Research and development	39,858,000	28,155,000
PORTOLA PHARMACEUTICALS INC
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development costs, percent	40.00%
Biogen Idec
Research And Development Arrangement Contract To Perform For Others [Line Items]
License fee receivable upon occurrence of certain development and regulatory events				370,000,000
Notice period for agreement termination				120 days
Payments Upon the Completion of Certain Commercial Milestones			15,000,000
Reduction in research and development expense	0	70,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee					13,000,000
Milestone Payments of Development and Regulatory Event					12,000,000
Percentage of consideration received under agreement					50.00%
Non-contingent consideration being recognized as revenue over estimated period of performance	6,500,000
Contingent consideration to be recognized after resolution of contingency	6,500,000
Collaboration and license revenue	380,000	442,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | January 2014 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue	11,100,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | Collaborative Arrangement | January 2014 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	380,000	442,000
Lee’s Pharmaceutical (HK) Ltd (“Lee’s”)
Research And Development Arrangement Contract To Perform For Others [Line Items]
Notice period for agreement termination						60 days
Upfront fee						700,000
Collaboration and license revenue	52,000	62,000
Deferred revenue	200,000
Lee’s Pharmaceutical (HK) Ltd (“Lee’s”) | Collaborative Arrangement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	52,000	62,000
Aciex Therapeutics, Inc. (“Aciex”)
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development costs, percent	60.00%
Percentage of profits entitle to receive under agreement	50.00%
Research and development	0	0
Bayer Pharma AG
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee							2,500,000
Additional non-refundable fee							250,000
Janssen Pharmaceuticals, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee							2,500,000
Additional non-refundable fee							250,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee							5,000,000
Additional non-refundable fee							500,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee					10,000,000
Milestone Payments of Development and Regulatory Event					8,000,000
Collaboration and license revenue	799,000	913,000
Contingent payment receivable upon achievement					7,000,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | January 2014 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue	9,700,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | February 2013 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue	0
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | Collaborative Arrangement | January 2014 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	799,000	511,000
Contingent Payments Received	3,000,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | Collaborative Arrangement | January 2014 Agreement | Future Contingent Payments
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	0
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | Collaborative Arrangement | February 2013 Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue		401,000
Daiichi Sankyo, Inc ("Daiichi")
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront fee								15,000,000
Milestone Payments of Development and Regulatory Event								20,000,000
Non-contingent consideration being recognized as revenue over estimated period of performance	3,000,000
Contingent consideration to be recognized after resolution of contingency	3,000,000
Collaboration and license revenue	1,128,000	955,000
Contingent payment receivable upon achievement								5,000,000
Collaborative arrangement upfront payment to be received									6,000,000
Upfront fee subject to refund									3,000,000
Daiichi Sankyo, Inc ("Daiichi") | Collaborative Agreement to Study Safety and Efficacy of Andexanet Alfa
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue	12,400,000
Daiichi Sankyo, Inc ("Daiichi") | Collaborative Agreement to Study Safety and Efficacy of Andexanet Alfa | Future Contingent Payments
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	0
Daiichi Sankyo, Inc ("Daiichi") | Collaborative Arrangement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Contingent consideration to be recognized after resolution of contingency	258,000	955,000
Deferred revenue	788,000
Daiichi Sankyo, Inc ("Daiichi") | Collaborative Arrangement | Collaborative Agreement to Study Safety and Efficacy of Andexanet Alfa
Research And Development Arrangement Contract To Perform For Others [Line Items]
Collaboration and license revenue	$ 871,000