Employee Retirement Plans (Accumulated Benefit Obligations, Amounts Recognized on Balance Sheets, and Reconciliation of AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax
Amount arising during the period	$ 20.4	$ 3.2
Impact of pension plan settlement charge included in net loss	0.9	0.1
Pension Benefits
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Current liabilities	(1.6)	(1.7)
Noncurrent liabilities	(17.6)	(54.9)
Total amount recognized	(19.2)	(56.6)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax
Accumulated other comprehensive income (loss), before Tax, beginning balance	(38.1)	(41.4)
Amount arising during the period	20.3	3.2
Impact of pension plan settlement charge included in net loss	0.9	0.1
Accumulated other comprehensive income (loss), before Tax, ending balance	(16.9)	(38.1)
Settlement charge	$ (0.9)	$ (0.1)