Liability Related to Sale of Future Royalties - Additional Information (Detail) (USD $)	12 Months Ended				3 Months Ended	9 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Purchase and Sale Agreement with RPI [Member]	Mar. 31, 2012 CIMZIA and MIRCERA [Member]	Dec. 31, 2012 CIMZIA and MIRCERA [Member]	Dec. 31, 2012 CIMZIA and MIRCERA [Member]	Dec. 31, 2012 MIRCERA [Member]	Dec. 31, 2012 Milestone Scenario One [Member]	Dec. 31, 2012 Milestone Scenario Two [Member]
Proceeds from sale of royalty rights				$ 124,000,000
Transaction costs related to sale of potential future royalties				4,400,000
Royalty revenues	4,874,000	10,327,000	7,255,000		2,700,000		13,500,000
Non-cash royalty revenue related to sale of future royalties	10,791,000					10,800,000
Annual interest rate	17.00%
Potential payments milestone not achieved year one									3,000,000
Potential payments milestone not achieved year two										7,000,000
Royalty agreement contingent payment description									If certain worldwide net sales thresholds of MIRCERAfor the 12 month period ending on December 31, 2012 are not achieved	If certain worldwide net sales thresholds of MIRCERAfor the 12 month period ending on December 31, 2013 are not achieved
Other current liabilities	$ 12,414,000	$ 4,681,000						$ 3,000,000