Collaboration Agreement - Additional Information (Detail) (USD $)	3 Months Ended			3 Months Ended	88 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Licensing Agreements Astellas Pharma Inc.	Mar. 31, 2013 Licensing Agreements Astellas Pharma Inc.	Mar. 31, 2012 Licensing Agreements Astellas Pharma Inc. Approval of Regnite in Japan	Mar. 31, 2013 Licensing Agreements Astellas Pharma Inc. Initial license payment	Mar. 31, 2012 Licensing Agreements Astellas Pharma Inc. Initial license payment
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized	$ 459,000	$ 10,379,000			$ 51,300,000	$ 10,000,000	$ 379,000	$ 379,000
Royalty revenue	80,000			80,000
Deferred revenue				13,889,000	13,889,000
Deferred revenue, current	1,515,000		1,515,000	1,515,000	1,515,000
Deferred revenue, noncurrent	$ 12,374,000		$ 12,753,000	$ 12,374,000	$ 12,374,000