Commitments and Contingencies - Research Collaboration and Licensing Agreements (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Agreements with Royalty Provisions
Research Collaboration and Licensing Arrangements [Line Items]
Royalty rate minimum	0.50%
Royalty rate maximum	16.50%
Royalty expense	$ 169,900,000	$ 128,100,000	$ 59,500,000
License agreement with Genentech - EYLEA
Research Collaboration and Licensing Arrangements [Line Items]
First payment made or maybe made upon reaching minimum sales target			60,000,000
Cumulative relevant sales minimum sales target			400,000,000
Cumulative sales range, 1st tier minimum	400,000,000
Sales range maximum 1st tier	3,000,000,000
Cumulative sales range, 2nd tier minimum	$ 3,000,000,000
Royalty payment percentage of cumulative sales within cumulative sales range	4.75%
Royalty payment percentage of cumulative sales over range	5.50%