Income Taxes - Reconciliation of Effective Income Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Percent and amount of pretax income
Federal statutory rate	21.00%	21.00%	21.00%
State and local income taxes, net of federal benefits	1.40%	9.90%	(6.20%)
Nondeductible expenses	(0.30%)	4.00%	6.90%
Goodwill impairment losses	(2.30%)	14.40%	0.00%
Compensation	2.50%	0.30%	(3.80%)
Foreign	0.00%	0.10%	(0.10%)
Federal valuation allowance	(3.90%)	0.00%	(20.30%)
Tax credits	1.20%	0.00%	0.00%
Other	0.20%	0.20%	(1.50%)
Total effective tax rate and income tax benefit (expense)	19.80%	49.90%	(4.00%)
Amount of pretax income
Federal statutory rate	$ 175.2	$ (18.1)	$ (18.9)
State and local income taxes - net of federal benefits	12.1	(8.5)	5.6
Nondeductible expenses	(2.6)	(3.5)	(6.2)
Goodwill impairment	(19.0)	(12.4)	0.0
Compensation	20.5	(0.3)	3.4
Foreign	(0.4)	(0.1)	0.1
Valuation allowance	(32.7)	0.0	18.3
Tax Act - deferred rate change	10.0	0.0	0.0
Other miscellaneous items	2.0	(0.1)	1.3
Total income tax benefit (expense)	$ 165.1	$ (43.0)	$ 3.6

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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