Collaboration Agreements - Collaboration Revenue and Collaboration Receivables - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Revenue Arrangement [Line Items]
Collaboration revenue percentage compared to U.S. XTANDI net sales	50.00%								50.00%
Collaboration revenue attributable to U.S. XTANDI sales	$ 96,612,000	$ 60,027,000	$ 70,149,000	$ 46,154,000	$ 37,161,000	$ 64,798,000	$ 42,912,000	$ 36,825,000	$ 272,942,000	$ 181,696,000	$ 60,389,000
Collaboration revenue attributable to ex-U.S. XTANDI sales									6,300,000	0	0
Collaboration receivable	$ 107,210,000				$ 35,458,000				$ 107,210,000	$ 35,458,000
Development cost-sharing payments [Member] | Collaborative agreement [Member] | Astellas Pharma Inc. [Member]
Deferred Revenue Arrangement [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] | Collaborative agreement [Member] | Astellas Pharma Inc. [Member]
Deferred Revenue Arrangement [Line Items]
Share of developing and commercializing XTANDI U.S.									50.00%
Share of developing and commercializing XTANDI ex-U.S.									66.67%