Income Taxes Narrative (Details) $ in Millions		12 Months Ended
	Dec. 22, 2017 USD ($)	Dec. 31, 2017 USD ($) country	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Tax Credit Carryforward [Line Items]
Tax Cuts and Jobs Act of 2017, provisional income tax expense	$ 57.0
Tax Cuts and Jobs Act of 2017, undistributed accumulated earnings of foreign subsidiary		$ 720.0
Income tax credits		21.0	$ 30.9
Net operating loss carryforwards		19.0	27.2
Valuation allowance		19.4	22.6
Income taxes paid		130.8	117.4	$ 139.1
Unrecognized tax benefits timing of deductibility unknown		0.9
Unrecognized tax benefits, income tax penalties and interest expense		0.5	0.7	$ 1.2
Unrecognized tax benefits, income tax penalties and interest accrued		5.2	$ 4.8
Minimum
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits that would impact effective tax rate		15.9
Significant (increase) decrease in unrecognized tax benefits is reasonably possible, estimated range of change, upper bound		1.0
Maximum
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits that would impact effective tax rate		26.1
Significant (increase) decrease in unrecognized tax benefits is reasonably possible, estimated range of change, upper bound		11.8
Federal, State, and Local
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards		19.0
Tax credit carryforward indefinitely
Tax Credit Carryforward [Line Items]
Income tax credits		12.7
Net operating loss carryforwards		9.1
Carryforward Subject To Expiration
Tax Credit Carryforward [Line Items]
Income tax credits		8.3
Net operating loss carryforwards		$ 9.9
Non-US
Tax Credit Carryforward [Line Items]
Number of countries in which entity operates | country		17