Collaborative Agreements (Details) (USD $)	3 Months Ended		1 Months Ended		3 Months Ended	12 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Apr. 30, 2010 Takeda	Mar. 31, 2010 Takeda	Mar. 31, 2013 Takeda item	Dec. 31, 2012 Takeda	Dec. 31, 2010 Takeda	Mar. 31, 2013 Takeda Maximum
Collaborative Agreements
Number of deliverables					4
Upfront payment received			$ 60,000,000
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
Milestone revenue received						18,000,000
License fee and other collaboration revenues	2,003,000	1,753,000			2,000,000
Milestone payments revenue recognized under the agreement					500,000
Deferred revenue recognized in earnings related to upfront payment					1,500,000
Other reimbursement revenues								100,000
Product sales and royalty revenue recognized								100,000
Deferred revenues					1,100,000
Deferred costs					$ 1,000,000