Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended		24 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 26.4	$ 25.7	$ 26.4
Unrecognized tax benefits that would impact effective tax rate	62.0		62.0
Unrecognized tax benefits, income tax penalties and interest expense	1.7
Accrued interest and penalties	6.9	5.1	6.9
Expected decrease of unrecognized tax benefits	2.3		2.3
Tax Act, total impact, income tax benefit			229.5
Tax Act, provisional income tax benefit		215.4
Tax Act, measurement period adjustment, income tax benefit	14.1
Tax Act, change in tax rate, income tax benefit		379.0
Tax Act, mandatory repatriation on undistributed foreign earnings, total income tax expense			102.4
Tax Act, mandatory repatriation on undistributed foreign earnings, provisional income tax expense		110.7
Tax Act, mandatory repatriation on undistributed foreign earnings, measurement period adjustment, income tax benefit	8.3
Tax Act, repatriation of foreign earnings, change in assertion, total income tax expense			22.8
Tax Act, repatriation of foreign earnings, change in assertion, provisional income tax expense		28.7
Tax Act, repatriation of foreign earnings, change in assertion, measurement period adjustment, income tax benefit	5.8
Tax Cuts and Jobs Act of 2017, write off of foreign tax credits		$ 24.2
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	19.7		19.7
Valuation allowance	9.1		9.1
Internal Revenue Service (IRS) | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	8.0		8.0
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	32.2		32.2
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	22.8		22.8
Valuation allowance	$ 17.3		$ 17.3