Collaborative Agreements (Details) (USD $)			1 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Apr. 30, 2010 Takeda	Mar. 31, 2010 Takeda	Mar. 31, 2014 Takeda	Dec. 31, 2010 Takeda	Mar. 31, 2013 Takeda Maximum	Mar. 31, 2014 Takeda Maximum	Mar. 31, 2014 3SBio License Agreement	Dec. 31, 2008 3SBio License Agreement
Collaborative Agreements
Upfront payment received			$ 60,000,000							$ 1,000,000
Additional upfront payment						1,000,000
Period of recognition of deferred revenues				10 years
Milestone payments expected to be received under the agreement								186,000,000
Deferred revenue recognized in earnings related to upfront payments					2,000,000				1,000,000
Other reimbursement revenues					100,000		100,000
Product sales and royalty revenue recognized					200,000
Deferred revenues					2,300,000
Deferred revenues, short-term	9,118,000	8,226,000			1,200,000
Deferred revenues, long-term	40,567,000	44,534,000			1,100,000
Deferred costs					2,200,000
Deferred costs, short-term					1,100,000
Deferred costs, long-term					$ 1,100,000