Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 258.3	$ 239.9
Finance and operating lease obligations	22.6	19.7
Pension and postretirement benefits	36.0	50.4
Employee benefits	5.8	9.1
Interest limitation	4.9	0.0
State tax credit	8.6	9.0
Other	24.4	31.4
Total deferred tax assets	360.6	359.5
Valuation allowance	(18.4)	(28.4)
Total deferred tax assets, net of valuation allowance	342.2	331.1
Deferred tax liabilities:
Property, plant and equipment and intangibles	(475.5)	(250.9)
Other	(1.0)	(8.6)
Total deferred tax liabilities	(476.5)	(259.5)
Net deferred tax liabilities	$ (134.3)
Net deferred tax assets		$ 71.6