Income Taxes - Income Tax Provisions (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal									$ 17.4	$ 10.6	$ (2.2)
State									4.4	3.7	0.9
Current Foreign Tax Expense (Benefit)									1.8	0.0	0.0
Total current tax provision (benefit)									23.6	14.3	(1.3)
Deferred:
Federal									(3.1)	(0.5)	(5.3)
State									(0.9)	0.1	1.4
Foreign									0.1	0.5	0.1
Total deferred tax (benefit) provision									(3.9)	0.1	(3.8)
Income tax provision (benefit)	$ 4.6	$ 8.1	$ 6.5	$ 0.5	$ 3.1	$ 7.4	$ 4.4	$ (0.5)	$ 19.7	$ 14.4	$ (5.1)