Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Foreign operating loss carryforwards	$ 24.8
Operating Loss Carryforwards, Net of Valuation Allowance	0.4
Other income (expense)
Income Taxes
Income tax expense (benefit)	20.9	$ 18.3	$ 20.1
Tax years between 2018 and 2024
Income Taxes
Operating loss carryforwards	$ 14.0