Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Accruals not yet deductible for tax purposes	$ 17.1	$ 16.0
Net operating loss carryforwards	219.4	252.1
Foreign, federal and state credits	6.4	6.5
Employee benefit items	45.4	78.7
Capitalized expenses	3.9	6.2
Intangibles	15.4	24.9
Derivatives and other	45.4	59.8
Sub-total deferred tax assets	353.0	444.2
Valuation allowance	(189.6)	(207.1)
Total deferred tax assets	163.4	237.1
Depreciation and amortization	(78.6)	(66.0)
Unremitted foreign earnings	0.0	(11.0)
Intangible assets	0.0	0.0
Other	(0.2)	(4.0)
Total deferred tax liabilities	(78.8)	(81.0)
Net deferred tax assets	$ 84.6	$ 156.1