Description of Business - Additional Information (Detail) - Jun. 30, 2015 $ in Millions	USD ($) Product	USD ($) Product
Convertible Senior Notes Due 2017 [Member] | Senior Notes [Member]
Organization And Description Of Business [Line Items]
Debt instrument, interest rate	2.625%	2.625%
Convertible Notes, maturity date	Apr. 01, 2017
Astellas Pharma Inc. [Member] | Milestone and cost-sharing payments [Member]
Organization And Description Of Business [Line Items]
Remaining sales milestone payments may receive	$ 245.0
XTANDI [Member]
Organization And Description Of Business [Line Items]
Number of commercial products | Product	1	1
XTANDI [Member] | Astellas Pharma Inc. [Member]
Organization And Description Of Business [Line Items]
World wide net sales		$ 2,400.0
Collaborative agreement [Member] | Astellas Pharma Inc. [Member]
Organization And Description Of Business [Line Items]
Range of percentage rates for royalties received on ex-U.S. net sales, as defined by collaboration agreement	Low teens to the low twenties