Income Taxes Income Taxes - Income Tax (Benefit) Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Current federal tax expense (benefit)	$ (1.4)	$ (0.2)	$ 5.9
Current state and local tax expense (benefit)	2.1	1.5	1.7
Current foreign tax expense (benefit)	4.2	8.2	(4.0)
Current income tax expense (benefit)	4.9	9.5	3.6
Deferred federal income tax expense (benefit)	7.1	(10.4)	6.5
Deferred state and local income tax expense (benefit)	1.9	(1.9)	1.0
Deferred foreign income tax expense (benefit)	0.1	(1.2)	2.0
Deferred income tax expense (benefit)	9.1	(13.5)	9.5
Income tax expense (benefit)	$ 14.0	$ (4.0)	$ 13.1