Income Taxes - Schedule of Components of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current provision:
Federal	$ 19.2	$ 10.1	$ 29.5
State and local	6.0	3.8	3.0
Current income tax expense (benefit)	25.2	13.9	32.5
Deferred provision (benefit):
Federal	16.1	35.0	(53.0)
State and local	15.5	2.5	0.8
Foreign	0.0	(0.1)	(0.2)
Deferred income tax expense (benefit)	31.6	37.4	(52.4)
Income tax expense (benefit)	$ 56.8	$ 51.3	$ (19.9)