Collaboration Agreements - Schedule of Collaboration Revenue Attributable to Sales (Detail) (U.S. XTANDI sales [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Collaborative Arrangements [Line Items]
Shared U.S. development and commercialization costs	$ (61,431)	$ (119,101)
Pre-tax U.S. profit	20,971	38,679
Collaboration revenue attributable to U.S. XTANDI sales	41,201	78,890
Astellas [Member]
Collaborative Arrangements [Line Items]
Net U.S. sales (as reported by Astellas)	82,402	157,780
Medivation [Member]
Collaborative Arrangements [Line Items]
Medivation's share of pre-tax U.S. profit	10,486	19,340
Reimbursement of Medivation's share of shared U.S. costs	$ 30,715	$ 59,550