Collaboration Agreements (EYLEA) (Details) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)
Collaboration Agreement [Line Items]
Number of sales milestone payments the Company received		1				3
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
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		$ 15,000		$ 15,000	45,000
Levels of twelve month sales at which sales milestone payments were received - 200 million		$ 200,000
Reimbursement of Regeneron research and development expenses	2,464		$ 1,494		$ 5,121	$ 21,841
PDGF
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized	$ 5,000
BRVO
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses				$ 15,700