Collaborative Agreements (Details) (USD $)	3 Months Ended								12 Months Ended			1 Months Ended			12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2012	Apr. 30, 2010	Mar. 31, 2010	Dec. 31, 2010	Dec. 31, 2008
Collaborative Agreements
Cost of product sales	$ 11,758,000	$ 2,968,000	$ 2,743,000	$ 2,837,000	$ 3,326,000	$ 2,547,000	$ 3,145,000	$ 2,942,000	$ 20,306,000	$ 11,960,000	$ 14,220,000
Deferred revenues, short-term	44,376,000				8,226,000				44,376,000	8,226,000
Deferred revenues, long-term					44,534,000					44,534,000
License Development and Commercialization Agreement with Takeda [Member]
Collaborative Agreements
Number of deliverables	4								4
Upfront payment received													60,000,000
Additional upfront payment															1,000,000
Period of recognition of deferred revenues									12 months					10 years
Milestone payments revenue recognized under the agreement									8,200,000			15,000,000
Milestone revenue											18,000,000
Other reimbursement revenues									1,700,000	500,000	400,000
Product sales and royalty revenue recognized									3,500,000
Cost of product sales									2,800,000
Accelerated Recognition Of Deferred Revenue									300,000
Deferred revenues, short-term	3,200,000								3,200,000
License Development and Commercialization Agreement with Takeda [Member] | Termination Agreement [Member]
Collaborative Agreements
Milestone revenue									3,000,000
Other reimbursement revenues									6,700,000
Transfer period									60 days
Extension period									30 days
Transition period									180 days
Transition extension period									180 days
Percentage paid									5.00%
Withdrawal period									120 days
Collaboration and Exclusive License Agreement with 3SBio Inc [Member]
Collaborative Agreements
Upfront payment received																$ 1,000,000