Collaboration Agreements (EYLEA) (Details) $ in Thousands	3 Months Ended					6 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Collaboration Agreement [Line Items]
Number of sales milestone payments the Company received			1	2		5
Number of development milestone payments the Company received						3,000,000
Levels of twelve month sales at which sales milestone payments were received - 500 million						$ 500,000
Levels of twelve month sales at which sales milestone payments were received - 600 million						600,000
Levels of twelve month sales at which sales milestone payments were received - 700 million						$ 700,000
Levels of twelve month sales at which sales milestone payments were received - 800 million				$ 800,000
Levels of twelve month sales at which sales milestone payments were received - 900 million				900,000
Period for Achieving Sales Target for Milestone Payment, Rolling Basis			12 months			12 months
sales achievement - $500 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized						$ 15,000
sales achievement - $600 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized						15,000
sales achievement - $700 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized						$ 15,000
sales achievement - $200 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized			$ 15,000
Collaboration Agreement with Bayer HealthCare LLC [Member]
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized	$ 0			30,000			$ 15,000	$ 75,000
Levels of twelve month sales at which sales milestone payments were received - 200 million			$ 200,000
Reimbursement of Regeneron research and development expenses	$ 1,827			$ 4,394			$ 6,948	$ 26,235
PDGF
Collaboration Agreement [Line Items]
Number of development milestone payments the Company received		1			2
Revenue Recognition, Milestone Method, Revenue Recognized		$ 5,000
BRVO
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses					$ 15,700