Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective tax rate	5.30%	8.50%	16.90%	13.20%
Tax benefit from release of uncertain tax positions due to the expiration of statute of limitations	$ 7.9		$ 7.9
Tax benefit for international statutory tax transaction			9.8
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			20.9
Net unrecognized tax benefit	69.2		69.2		$ 69.8
Income tax interest and penalties accrued	2.4		2.4
Deferred tax assets	$ 194.5		$ 194.5
U.S. federal statutory rate			35.00%