Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Examination [Line Items]
Federal corporate tax rate		35.00%	35.00%	35.00%
Tax benefit recognized due to change in U.S. corporate income tax rate		$ (110.5)
Increase (decrease) in net liability for unrecognized tax benefits		(1.6)	$ (1.1)
Accrued interest expense		0.2	0.2
Unrecognized tax benefits that would impact our effective tax rate		2.3	3.9
Interest included in total liability		0.4	$ 1.1
Significant increases or decreases for uncertain tax positions		$ 0.0
State and Foreign Tax Authorities | Minimum
Income Tax Examination [Line Items]
Period of statute of limitations (years)		3 years
State and Foreign Tax Authorities | Maximum
Income Tax Examination [Line Items]
Period of statute of limitations (years)		4 years
Statutory federal income tax rate [Domain]
Income Tax Examination [Line Items]
Federal corporate tax rate	21.00%