Collaboration and License Agreements - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		1 Months Ended		3 Months Ended			3 Months Ended			3 Months Ended	1 Months Ended		3 Months Ended			1 Months Ended					3 Months Ended		3 Months Ended		6 Months Ended	3 Months Ended
	Nov. 30, 2012 Biogen Idec	Mar. 31, 2014 Biogen Idec	Mar. 31, 2013 Biogen Idec	Apr. 30, 2014 Biogen Idec Subsequent Event	Jan. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Mar. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Dec. 31, 2013 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Mar. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") October 2012 Agreement	Mar. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") October 2012 Agreement Collaborative Arrangement	Mar. 31, 2013 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") October 2012 Agreement Collaborative Arrangement	Mar. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") January 2014 Agreement	Mar. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") January 2014 Agreement Collaborative Arrangement	Jan. 31, 2013 Lee's Pharmaceutical (HK) Ltd (“Lee's”)	Mar. 31, 2014 Lee's Pharmaceutical (HK) Ltd (“Lee's”)	Mar. 31, 2014 Lee's Pharmaceutical (HK) Ltd (“Lee's”) Collaborative Arrangement	Mar. 31, 2013 Lee's Pharmaceutical (HK) Ltd (“Lee's”) Collaborative Arrangement	Mar. 31, 2014 Aciex Therapeutics, Inc. (“Aciex”)	Feb. 01, 2013 Bayer Pharma AG	Feb. 01, 2013 Janssen Pharmaceuticals, Inc.	Jan. 31, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Feb. 01, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Mar. 31, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") January 2014 Agreement	Mar. 31, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") January 2014 Agreement Collaborative Arrangement	Mar. 31, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement	Mar. 31, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement Collaborative Arrangement	Mar. 31, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement Collaborative Arrangement	Jun. 30, 2013 Daiichi Sankyo, Inc ("Daiichi")	Mar. 31, 2014 Daiichi Sankyo, Inc ("Daiichi") Collaborative Arrangement	Mar. 31, 2013 Daiichi Sankyo, Inc ("Daiichi") Collaborative Arrangement	Mar. 31, 2014 Daiichi Sankyo, Inc ("Daiichi") Second Quarter	Mar. 31, 2014 Daiichi Sankyo, Inc ("Daiichi") First Quarter	Mar. 31, 2014 PORTOLA PHARMACEUTICALS INC
Research And Development Arrangement Contract To Perform For Others [Line Items]
License fee receivable upon occurrence of certain development and regulatory events	$ 370,000,000
Notice period for agreement termination	120 days												60 days
Payments Upon the Completion of Certain Commercial Milestones				15,000,000
Reduction in research and development expense		70,000	330,000
Deferred revenue							6,000,000	0			12,600,000			444,000								9,500,000		722,000				2,600,000
Collaboration revenue recognized									0	2,000,000		442,000			62,000	0							511,000		401,000	1,100,000		955,000	0
Upfront fee					13,000,000								700,000					2,500,000	2,500,000	10,000,000	5,000,000
Milestone Payments of Development and Regulatory Event					12,000,000															8,000,000
Percentage of consideration received under agreement					50.00%
Non-contingent consideration being recognized as revenue over estimated period of performance						6,500,000																								3,000,000	3,000,000
Contingent consideration to be recognized after resolution of contingency						6,500,000																									3,000,000
Development costs, percent																	60.00%															40.00%
Additional non-refundable fee																		250,000	250,000		500,000
Contingent payment payable upon achievement																				7,000,000
Collaborative arrangement upfront payment to be received																											6,000,000
Upfront fee subject to refund																											$ 3,000,000