Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective tax rate	41.40%	15.70%
Income tax charge due to change in expectation of realizibility of R&D credits	$ 46.1
Income tax benefit for first quarter results of share-based payments to employees	17.8
Net unrecognized tax benefit	73.4		$ 69.8
Income tax interest and penalties accrued	2.8
Deferred tax assets	163.8
Valuation allowance	$ 61.9
U.S. federal statutory rate	35.00%