Product Revenue (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Concentration Risk [Line Items]
Net product sales		$ 44,686,000	$ 25,254,000	$ 18,364,000
EYLEA Net Product Sales [Member] | Product Concentration Risk [Member]
Concentration Risk [Line Items]
Net product sales		24,800,000
ARCALYST Net Product Sales [Member] | Product Concentration Risk [Member]
Concentration Risk [Line Items]
Deferred net product sales recognized as revenue	4,800,000
Change in accounting estimate, deferred revenue - lower net loss per share (in dollars per share)			$ (0.06)
Net product sales		19,900,000	25,300,000	18,400,000
Net product sales, excluding deferred sales recognized as revenue			$ 20,500,000