Collaboration Agreements (Bayer HealthCare LLC) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Collaboration Agreement [Line Items]
Deferred Revenue, Additions			$ 25,500,000
Other Collaboration Revenue	97,295,000	31,104,000	222,607,000	46,011,000
EYLEA
Collaboration Agreement [Line Items]
Net profit (loss) from commercialization of products under collaboration agreement	66,781,000	19,055,000	127,940,000	25,417,000
Revenue Recognition, Milestone Method, Revenue Recognized	15,000,000	0	45,000,000	0
Reimbursement of Regeneron research and development expenses	1,494,000	3,629,000	21,841,000	9,466,000
Contracts Revenue	10,813,000	8,420,000	21,745,000	11,128,000
Other Collaboration Revenue	94,088,000	31,104,000	216,526,000	46,011,000
PDGFR-beta
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses	626,000	0	1,139,000	0
Deferred Revenue, Additions	2,581,000	0	4,942,000	0
Other Collaboration Revenue	$ 3,207,000	$ 0	$ 6,081,000	$ 0