Income Taxes - Components of Deferred Tax Liabilities (Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Depreciation	$ 99.5	$ 109.0
Right of use - leases	93.7	0.0
Deferred revenue	6.3	9.3
Intangibles	3.4	6.0
State taxes	19.6	19.9
Other	16.0	15.2
Deferred tax liabilities	238.5	159.4
Claims and insurance	(89.9)	(84.8)
Net operating loss carryforwards	(210.7)	(199.9)
Employee benefit accruals	(94.8)	(88.9)
Deferred Tax Asset, Sale Leaseback Transaction	(55.5)	(54.5)
Lease liabilities	(93.8)	0.0
Other	(28.4)	(20.6)
Deferred tax assets	(573.1)	(448.7)
Valuation allowance	334.0	291.1
Net deferred tax assets	(239.1)	(157.6)
Net deferred tax (asset) liability	$ (0.6)
Net deferred tax (asset) liability		$ 1.8