License and Collaboration Agreements - Schedule of Revenue Recognized and Assets and Liabilities under Collaborative Arrangements (Detail) (License and Collaboration Agreements [Member], Sanofi [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
License and Collaboration Agreements [Member] | Sanofi [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment	$ 5,000	$ 5,000	$ 5,000
Milestone payment	2,083	2,975	2,616
Development services	36,283	36,905	25,053
Manufacturing services and other	3,867	3,307	1,456
Total	47,233	48,187	34,125
Accounts receivable, billed	2,357	1,577
Accounts receivable, unbilled	3,417	7,690
Deferred revenues	$ 73,392	$ 79,913