Collaboration and License Agreements - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		1 Months Ended		3 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended			3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended	1 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		1 Months Ended					3 Months Ended	6 Months Ended			3 Months Ended		6 Months Ended				9 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Apr. 30, 2014 Biogen Idec	Nov. 30, 2012 Biogen Idec	Jun. 30, 2014 Biogen Idec	Jun. 30, 2013 Biogen Idec	Jun. 30, 2014 Biogen Idec	Jun. 30, 2013 Biogen Idec	Jan. 31, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Dec. 31, 2013 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") October 2012 Agreement	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") October 2012 Agreement Collaborative Arrangement	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") October 2012 Agreement Collaborative Arrangement	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") January2014 Agreement	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") January2014 Agreement Collaborative Arrangement	Jun. 30, 2014 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") January2014 Agreement Collaborative Arrangement	Jan. 31, 2013 Lee's Pharmaceutical (HK) Ltd (“Lee's”)	Jun. 30, 2014 Lee's Pharmaceutical (HK) Ltd (“Lee's”)	Jun. 30, 2014 Lee's Pharmaceutical (HK) Ltd (“Lee's”) Collaborative Arrangement	Jun. 30, 2013 Lee's Pharmaceutical (HK) Ltd (“Lee's”) Collaborative Arrangement	Jun. 30, 2014 Lee's Pharmaceutical (HK) Ltd (“Lee's”) Collaborative Arrangement	Jun. 30, 2013 Lee's Pharmaceutical (HK) Ltd (“Lee's”) Collaborative Arrangement	Jun. 30, 2014 Aciex Therapeutics, Inc. (“Aciex”)	Jun. 30, 2013 Aciex Therapeutics, Inc. (“Aciex”)	Jun. 30, 2014 Aciex Therapeutics, Inc. (“Aciex”)	Jun. 30, 2013 Aciex Therapeutics, Inc. (“Aciex”)	Feb. 28, 2013 Bayer Pharma AG	Feb. 28, 2013 Janssen Pharmaceuticals, Inc.	Jan. 31, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Feb. 28, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") January2014 Agreement	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") January2014 Agreement Collaborative Arrangement	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") January2014 Agreement Collaborative Arrangement	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") January2014 Agreement Collaborative Arrangement Future Contingent Payments	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement Collaborative Arrangement	Jun. 30, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement Collaborative Arrangement	Jun. 30, 2014 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement Collaborative Arrangement	Jun. 30, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") February 2013 Agreement Collaborative Arrangement	Jun. 30, 2014 Daiichi Sankyo, Inc ("Daiichi")	Jun. 30, 2013 Daiichi Sankyo, Inc ("Daiichi")	Mar. 31, 2014 Daiichi Sankyo, Inc ("Daiichi")	Jun. 30, 2014 Daiichi Sankyo, Inc ("Daiichi") Collaborative Arrangement	Jun. 30, 2013 Daiichi Sankyo, Inc ("Daiichi") Collaborative Arrangement	Jun. 30, 2014 Daiichi Sankyo, Inc ("Daiichi") Collaborative Arrangement	Jun. 30, 2013 Daiichi Sankyo, Inc ("Daiichi") Collaborative Arrangement	Jun. 30, 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							86,000	164,000	156,000	494,000
Deferred revenue													6,000,000	0			12,100,000				380,000													8,700,000				316,000								2,000,000		2,000,000
Collaboration revenue recognized															1,100,000	3,100,000		503,000	945,000			63,000	52,000	125,000	52,000										788,000	1,300,000	0		406,000	1,300,000	807,000	2,400,000				655,000	125,000	1,600,000	125,000
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
Contingent consideration to be recognized after resolution of contingency												6,500,000																															3,000,000
Development costs, percent																												60.00%																						40.00%
Research and development	28,983,000	20,833,000	57,138,000	38,556,000																						0	0	0	0
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