Income Taxes - Reconciliation of Amount Computed by Applying the Federal Statutory Income Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Federal statutory tax on earnings before income taxes	$ 1.7	$ 41.2	$ 49.1
State income taxes, net of federal income tax benefit	(0.6)	8.0	5.4
Net operating loss carry back - CARES Act	(13.3)	0.0	0.0
Windfall deduction from equity compensation	(5.1)	(5.2)	(4.7)
Non-deductible officer's compensation	7.3	5.5	2.6
Re-measurement of deferred taxes	1.9	8.3	0.0
Uncertain tax positions	1.7	(1.0)	0.0
Valuation allowance - state and foreign net operating losses	1.1	0.0	0.0
Other	0.0	0.0	(1.1)
Income tax (benefit) provision	$ (5.3)	$ 56.8	$ 51.3