Income Taxes (Stock Option Deductions Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 27, 2015
Business Acquisition [Line Items]
Increase in additional paid-in capital on realization of stock option deduction benefits for income tax purposes	$ 302.1	$ 252.6	$ 170.0
Deferred income taxes recorded as a component of accumulated other comprehensive income resulting in a deferred income tax asset	129.9	236.5
Deferred tax liability related to acquisition	$ 312.1	$ 618.5
Receptos
Business Acquisition [Line Items]
Deferred tax liability related to acquisition				$ 2,519.0