Income Taxes - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Aug. 31, 2019	Jun. 30, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Holiday [Line Items]
Provisional income tax expense											$ 0.0	$ 0.5	$ 317.8
U.S. tax on foreign earnings											55.0	43.7	8.4
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit)													47.6
Estimated cumulative undistributed foreign earnings		$ 1,600.0
Deferred tax remeasurement due to Swiss Tax Reform	$ 51.3										51.3	0.0	0.0
Valuation allowance			$ (57.2)				$ (42.3)				(57.2)	(42.3)
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount			33.7	$ 28.8	$ 11.3	$ 72.7	15.8	$ 24.1	$ 21.6	$ 54.7	146.5	116.2	102.8
Total gross unrecognized tax benefits			96.7				78.8				96.7	78.8	65.4	$ 106.0
Net increase in gross unrecognized tax benefits											17.9
Interest and penalties related to unrecognized tax benefits accrued			$ 2.9				$ 2.6				$ 2.9	$ 2.6	1.8
Swiss Federal Tax Administration (FTA)
Income Tax Holiday [Line Items]
Tax benefit from tax holiday													$ 10.9
Tax benefit from tax holiday (in dollars per share)													$ 0.09
Pro forma
Income Tax Holiday [Line Items]
U.S. tax on foreign earnings													$ 270.2