Liability Related to Sale of Future Royalties (Details Textual) (USD $)			3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Purchase and Sale Agreement with RPI [Member]	Mar. 31, 2012 CIMZIA and MIRCERA [Member] Purchase and Sale Agreement with RPI [Member]	Mar. 31, 2011 CIMZIA and MIRCERA [Member] Purchase and Sale Agreement with RPI [Member]	Mar. 31, 2012 Milestone Scenario One [Member] Purchase and Sale Agreement with RPI [Member]	Mar. 31, 2012 Milestone Scenario Two [Member] Purchase and Sale Agreement with RPI [Member]
Liability Related to Sale of Future Royalties (Textual) [Abstract]
Proceeds from sale of royalty rights			$ 124,000,000
Transaction costs related to sale of potential future royalties			4,400,000
Potential payments milestone not achieved year one						3,000,000
Potential payments milestone not achieved year two							7,000,000
Liability related to sale of future royalties	125,785,000
Royalty agreement contingent payment description						if certain worldwide net sales thresholds of MIRCERA® for the 12 month period ending on December 31, 2012 are not achieved	if certain worldwide net sales thresholds of MIRCERA® for the 12 month period ending on December 31, 2013 are not achieved
Royalty Revenue				$ 2,700,000	$ 1,800,000
Effective interest rate under royalty agreement			17