Income Taxes - Schedule of a Reconciliation of the Provision for Income Taxes at the U.S. Federal Statutory Income Tax Rate to the Actual Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of provision for income taxes at U.S. federal statutory income tax rate to effective income tax rate
Provision for taxes at U.S. federal statutory rate	$ 113.1	$ 118.2	$ 111.4
State and local taxes, net of federal benefit	0.2	3.1	2.5
Foreign effective rate differential	(14.4)	(26.8)	(22.6)
Tax credits	(16.0)	(10.1)	(3.1)
Change in Valuation Allowance	(9.1)	10.4	3.1
Remeasurement of deferred taxes	(67.8)
Transition Tax on undistributed foreign earnings	45.7
Excess Tax Benefits of Stock Based Compensation	(7.6)	(2.8)
Other	4.9	4.9	3.3
Release of reserves for uncertain tax positions	(6.5)	(6.6)	(11.6)
Total provision for income taxes	$ 42.5	$ 90.3	$ 83.0