Collaboration Agreement - Collaboration Revenue and Collaboration Receivables - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
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	$ 9,992,000	$ 482,000	$ 15,723,000	$ 482,000
Deferred revenue, Current	8,466,000		8,466,000		16,931,000
Development cost-sharing payments [Member] | Astellas Pharma Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development cost-sharing payments	17,500,000	11,300,000	33,400,000	18,500,000
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 Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Commercialization cost-sharing payments	$ 2,600,000	$ 3,800,000	$ 10,200,000	$ 8,600,000
Commercial cost sharing-payments [Member] | Collaborative agreement [Member] | Astellas Pharma 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.			66.67%