Collaboration Agreement - Schedule of Potential Milestone Payments in Sales (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone Payment	$ 50.0	$ 25.0
Milestone Payment Three [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Remaining future milestone payments eligible to receive			$ 70.0
Milestone Payment Four [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Remaining future milestone payments eligible to receive			175.0
Milestone Sales One [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Annual global net sales of XTANDI (calendar year), as reported by Astellas			400.0
Milestone Sales Two [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Annual global net sales of XTANDI (calendar year), as reported by Astellas			800.0
Milestone Sales Three [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Annual global net sales of XTANDI (calendar year), as reported by Astellas			1,200.0
Milestone Sales Four [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Annual global net sales of XTANDI (calendar year), as reported by Astellas			$ 1,600.0