Collaboration and License Agreements - Additional Information (Detail) - USD ($)	1 Months Ended								3 Months Ended					6 Months Ended	24 Months Ended
	Mar. 31, 2016	Feb. 29, 2016	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Feb. 28, 2013	Jan. 31, 2013	Nov. 30, 2012	Mar. 31, 2016	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2015
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue									$ 8,258,000		$ 2,359,000
Research and development									58,813,000		39,858,000
Daiichi Sankyo, Inc ("Daiichi")
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative arrangement upfront payment to be received														$ 6,000,000
Upfront fee subject to refund														$ 3,000,000
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
Contingent and non-contingent consideration to be recognized after resolution of contingency											258,000
Deferred revenue	$ 0								0
Upfront fee			$ 15,000,000
Contingent payment receivable upon achievement			5,000,000
Milestone Payments of Development and Regulatory Event			$ 20,000,000
Collaboration and license revenue									3,385,000		1,128,000
Daiichi Sankyo, Inc ("Daiichi") | March 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	5,000,000								5,000,000
Collaboration and license revenue									5,000
Daiichi Sankyo, Inc ("Daiichi") | Future Contingent Payments | March 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue									0
Daiichi Sankyo, Inc ("Daiichi") | Collaborative Agreement to Study Safety and Efficacy of Andexanet Alfa
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	$ 8,800,000								8,800,000
Collaboration and license revenue									3,400,000		871,000
Daiichi Sankyo, Inc ("Daiichi") | Collaborative Agreement to Study Safety and Efficacy of Andexanet Alfa | Future Contingent Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue									2,500,000		0
Daiichi Sankyo, Inc ("Daiichi") | ESS-Study | March 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage	33.00%
Daiichi Sankyo, Inc ("Daiichi") | Edoxaban | March 2016 Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage	33.00%
Daiichi Sankyo, Inc ("Daiichi") | Edoxaban | March 2016 Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage	100.00%
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee	$ 5,000,000				$ 10,000,000	$ 5,000,000
Contingent payment receivable upon achievement	10,000,000				7,000,000
Milestone Payments of Development and Regulatory Event					8,000,000
Collaboration and license revenue									3,307,000		799,000
Reduced contingent payment receivable upon achievement	7,000,000
Additional non-refundable fee						500,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | February 2013 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborative Arrangement Payment Received										$ 500,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | January 2014 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	6,500,000								6,500,000
Collaboration and license revenue									3,300,000		799,000
Contingent Payments Received												$ 3,000,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | Future Contingent Payments | January 2014 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue									2,500,000		0
Bayer Pharma AG
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee		$ 5,000,000				2,500,000
Contingent payment receivable upon achievement		10,000,000
Collaboration and license revenue									260,000
Reduced contingent payment receivable upon achievement		$ 7,000,000
Additional non-refundable fee						250,000
Bayer Pharma AG | February 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	4,700,000								4,700,000
Collaboration and license revenue									260,000
Bayer Pharma AG | Future Contingent Payments | February 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue									0
Bayer Pharma AG | ESS-Study | February 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		33.00%
Bayer Pharma AG | Rivaroxaban | February 2016 Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		33.00%
Bayer Pharma AG | Rivaroxaban | February 2016 Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		100.00%
Janssen Pharmaceuticals, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee						2,500,000
Additional non-refundable fee						$ 250,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
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
Upfront fee					13,000,000
Contingent payment receivable upon achievement									4,000,000
Milestone Payments of Development and Regulatory Event					$ 12,000,000
Collaboration and license revenue									1,254,000		380,000
Percentage of consideration received under agreement					50.00%
Milestone payments of regulatory and clinical event									2,800,000
Milestone payments which remains payable									750,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | January 2014 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	12,200,000								12,200,000
Collaboration and license revenue									475,000		380,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | February 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	14,200,000								14,200,000
Collaboration and license revenue									$ 779,000
Upfront fee		$ 15,000,000
Contingent payment receivable upon achievement of regulatory events		20,000,000
Contingent payment receivable upon achievement of annual net sales volumes		$ 70,000,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | February 2016 Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of royalties entitle to receive under agreement									5.00%
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | February 2016 Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of royalties entitle to receive under agreement									15.00%
Lee’s Pharmaceutical (HK) Ltd (“Lee’s”)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue	$ 0								$ 0		200,000
Upfront fee							$ 700,000
Collaboration and license revenue									$ 52,000		52,000
Notice period for agreement termination							60 days
Ora, Inc. (“Ora”)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Notice period for agreement termination									90 days
Development costs, percent									60.00%
Percentage of profits entitle to receive under agreement									50.00%
Rights to buy compound interests and licensed agreements									Each party may also buy out the rights and interests in the licensed compound by paying the greater of $6.0 million or two times the actual aggregate development cost incurred by both parties before or 90 days after an End of Phase 2 meeting with the FDA.
Research and development									$ 351,000
Ora, Inc. (“Ora”) | PORTOLA PHARMACEUTICALS INC
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development costs, percent									40.00%
Biogen Idec
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License fee receivable upon occurrence of certain development and regulatory events								$ 370,000,000
Payments Upon the Completion of Certain Commercial Milestones				$ 15,000,000
Reduction in research and development expense									$ 0		$ 0