Collaboration Agreements (Schedule Of Collaboration Revenue Attributable To Sales) (Detail) (United States XTANDI Sales [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Collaborative Arrangements Non collaborative Arrangements And Business Acquisitions Transactions [Line Items]
Shared U.S. development and commercialization costs	$ (41,928)	$ (41,928)
Pre-tax U.S. profit (loss)	(27,816)	(27,816)
Collaboration revenue attributable to U.S. XTANDI sales	7,056	7,056
Astellas [Member]
Collaborative Arrangements Non collaborative Arrangements And Business Acquisitions Transactions [Line Items]
Net U.S. sales (as reported by Astellas)	14,112	14,112
Medivation [Member]
Collaborative Arrangements Non collaborative Arrangements And Business Acquisitions Transactions [Line Items]
Medivation's share of pre-tax U.S. profit (loss)	(13,908)	(13,908)
Reimbursement of Medivation's share of shared U.S. costs	$ 20,964	$ 20,964