Collaboration Agreements - Schedule of Potential Milestone Payments in Sales (Detail) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone Payment	$ 50,000,000	$ 25,000,000
Milestone Payment Three [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Remaining future milestone payments eligible to receive			70,000,000
Milestone Payment Four [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Remaining future milestone payments eligible to receive			175,000,000
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			400,000,000
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			800,000,000
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			1,200,000,000
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			$ 1,600,000,000