Collaboration Agreement - Substantive Development Milestone Payments Eligible to Receive under Astellas Collaboration Agreement (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
4th line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | The U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	$ 0
4th line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | The first major country in Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
4th line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
4th line prostate cancer patients [Member] | First approval of a marketing application [Member] | The U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
4th line prostate cancer patients [Member] | First approval of a marketing application [Member] | The first major country in Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
4th line prostate cancer patients [Member] | First approval of a marketing application [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
3rd line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | The U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
3rd line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | The first major country in Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
3rd line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
3rd line prostate cancer patients [Member] | First approval of a marketing application [Member] | The U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
3rd line prostate cancer patients [Member] | First approval of a marketing application [Member] | The first major country in Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	15
3rd line prostate cancer patients [Member] | First approval of a marketing application [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	15
2nd line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | The U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
2nd line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | The first major country in Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
2nd line prostate cancer patients [Member] | First acceptance for filing of a marketing application [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
2nd line prostate cancer patients [Member] | First approval of a marketing application [Member] | The U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	0
2nd line prostate cancer patients [Member] | First approval of a marketing application [Member] | The first major country in Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	30
2nd line prostate cancer patients [Member] | First approval of a marketing application [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments eligible to receive under Collaboration Agreement	$ 30