Collaboration Agreements - Collaboration Revenue and Collaboration Receivables - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue percentage compared to U.S. XTANDI net sales	50.00%	50.00%
Collaboration revenue related to ex-U.S. XTANDI sales	$ 49,500,000	$ 6,300,000	$ 0
Deferred revenue, Current	2,822,000	16,931,000
Collaboration receivable	184,737,000	107,210,000
Collaborative agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue, Current	2,800,000	16,900,000
Collaboration receivable	$ 184,700,000	$ 107,200,000
Development cost-sharing payments [Member] | Collaborative agreement [Member] | Medivation Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Share of developing and commercializing XTANDI U.S.	50.00%
Share of developing and commercializing XTANDI ex-U.S.	33.33%
Commercial cost sharing-payments [Member] | Astellas Pharma Inc. [Member] | Collaborative agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Share of developing and commercializing XTANDI U.S.	50.00%
Share of developing and commercializing XTANDI ex-U.S.	66.67%