Income Taxes - Schedule of Reconciliation of the Reported Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of income tax provision (benefit) to the amount computed by multiplying book income/(loss) before income taxes by federal income tax rate
Tax at statutory rate	$ (50.5)	$ 14.9	$ 16.0
Permanent differences	0.7	0.8	0.2
State taxes, net of federal benefit	(13.9)	4.5	6.3
Effect of foreign tax rates	0.4	0.6	0.6
Federal net operating loss carryback rate differential	(6.1)	0.0	0.0
Effect of 2017 Tax Act	0.0	0.0	(1.5)
Noncontrolling interest	0.0	(0.6)	(0.7)
Current year adjustment to deferred taxes	0.0	0.8	0.4
Recognition of tax credits	(0.5)	(1.8)	(2.7)
Income tax expense before change in valuation allowance	(69.9)	19.2	18.6
Change in valuation allowance	2.4	0.2	1.0
Income tax (benefit) expense	$ (67.5)	$ 19.4	$ 19.6
Effective tax rate	28.10%	27.30%	25.80%