Commitments and Contingencies - Research Collaboration and Licensing Agreements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	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	$ 247.9	$ 169.9	$ 128.1
License agreement with Genentech - EYLEA
Research Collaboration and Licensing Arrangements [Line Items]
First payment made or maybe made upon reaching minimum sales target				$ 60.0
Cumulative relevant sales minimum sales target				$ 400.0
Cumulative sales range, 1st tier minimum	400.0
Sales range maximum 1st tier	3,000.0
Cumulative sales range, 2nd tier minimum	$ 3,000.0
Royalty payment percentage of cumulative sales within cumulative sales range	4.75%
Royalty payment percentage of cumulative sales over range	5.50%