Income Taxes - Components of Benefit for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current
Federal	$ (6.4)	$ (3.2)	$ (1.1)
State	(12.6)	3.2	1.2
Current income tax expense	(19.0)	0.0	0.1
Deferred
Federal	(5.8)	6.2	(44.8)
State	4.4	(1.6)	3.5
Deferred income tax expense (benefit)	(1.4)	4.6	(41.3)
(Benefit) expense from income taxes	$ (20.4)	$ 4.6	$ (41.2)