Collaboration Agreements (Bayer) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015
Collaboration Agreement [Line Items]
Other Collaboration Revenue	$ 191,298	$ 157,596		$ 562,786	$ 415,679
EYLEA
Collaboration Agreement [Line Items]
Net profit (loss) from commercialization of products under collaboration agreement	170,854	130,510		484,181	326,567
Revenue Recognition, Milestone Method, Revenue Recognized				0	15,000
Reimbursement of Regeneron research and development expenses	2,219	1,827		7,186	6,948
Contracts Revenue	6,077	21,155		45,924	50,685
Other Collaboration Revenue	179,150	153,492		537,291	399,200
PDGFR-beta
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses	3,912	1,508		8,570	8,688
Contracts Revenue	2,603	2,596		7,836	7,791
Other Collaboration Revenue	6,515	4,104		16,406	16,479
Ang2
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses	3,521	0		5,595	0
Contracts Revenue	2,112	0		3,494	0
Other Collaboration Revenue	$ 5,633	$ 0		$ 9,089	$ 0
sales achievement - $200 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized			$ 15,000