Revision of Previously Issued Financial Statements - Condensed Consolidated Statement of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification [Line Items]
Net income	$ 13.7	$ 42.5	$ 57.9	$ 105.6
Amortization of actuarial losses, net of income taxes	5.2	11.5	15.6	34.5
Comprehensive income	$ 18.9	54.0	$ 73.5	140.1
Previously Reported
Reclassification [Line Items]
Net income		42.6		105.7
Amortization of actuarial losses, net of income taxes		11.5		34.5
Comprehensive income		54.1		140.2
Adjustments
Reclassification [Line Items]
Net income		(0.1)		(0.1)
Amortization of actuarial losses, net of income taxes		0.0		0.0
Comprehensive income		$ (0.1)		$ (0.1)