Income Taxes - Components of Income Tax Expense (Benefit), Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income taxes:
U.S. federal	$ 8.1	$ (9.2)	$ 53.2
U.S. state	0.8	0.8	0.6
Foreign	9.7	11.6	14.2
Current income taxes	18.6	3.2	68.0
Deferred income taxes:
U.S. federal	2.3	3.6	(1.3)
U.S. state	(1.9)	1.4	2.9
Foreign	(3.8)	2.5	0.0
Deferred income taxes	(3.4)	7.5	1.6
Provision for income taxes	$ 15.2	$ 10.7	$ 69.6