Collaboration Agreements - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended			3 Months Ended		6 Months Ended				3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Collaborative agreement [Member]	Jun. 30, 2013 Collaborative agreement [Member] Astellas [Member]	Dec. 31, 2009 Up-front cash payment arrangement [Member] Astellas [Member]	Dec. 31, 2008 Up-front cash payment arrangement [Member] Pfizer [Member]	Jun. 30, 2013 Development milestone payments [Member] Astellas [Member]	Jun. 30, 2013 Development milestone payments [Member] Astellas [Member]	Jun. 30, 2013 Sales milestone payments [Member] Astellas [Member]	Jun. 30, 2013 Development cost-sharing payments [Member] Collaborative agreement [Member] Astellas [Member]	Dec. 31, 2008 Development cost-sharing payments [Member] Collaborative agreement [Member] Pfizer [Member]	Jun. 30, 2013 Development cost-sharing payments [Member] Collaborative agreement [Member] Pfizer [Member]	Jun. 30, 2013 Commercial cost sharing-payments [Member] Collaborative agreement [Member] Astellas [Member]	Dec. 31, 2008 Commercial cost sharing-payments [Member] Collaborative agreement [Member] Medivation [Member]	Jun. 30, 2013 Commercial cost sharing-payments [Member] Collaborative agreement [Member] Medivation [Member]
Deferred Revenue Arrangement [Line Items]
Co-promotion of sales and medical affairs percentage			50.00%
Royalty received on ex-U.S. sales per collaboration arrangement				low teens to the low twenties
Non-refundable, up-front cash payment					$ 110,000,000	$ 225,000,000
Eligible to receive milestone payments							335,000,000
Eligible to receive milestone payments									320,000,000
Astellas development milestones received		63,000,000					63,000,000
Receivable from collaboration partner								15,000,000
Remaining development milestone payments the Company is eligible to receive								257,000,000
Percentage share of development milestone payments							10.00%	10.00%
Share percentage of developing and commercializing dimebon											60.00%	60.00%		40.00%	40.00%
Share of developing and commercializing XTANDI U.S.										50.00%			50.00%
Share of developing and commercializing XTANDI ex-U.S.										33.33%			66.67%
Collaboration revenue percentage compared to U.S. XTANDI net sales	50.00%	50.00%
Collaboration revenue attributable to ex-U.S. XTANDI sales	500,000	500,000
Aggregate upfront and milestones received			$ 173,000,000