Pensions and Postretirement Benefits - Summary of Change in Defined Benefit and Postretirement Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in plan assets
Fair value of plan assets at beginning of year	$ 131.5
Fair value of plan assets at end of year	147.9	$ 131.5
Funded (underfunded) status of the plans
Pension assets	75.1	63.9
Pension Benefits
Change in benefit obligation
Benefit obligation at beginning of year	67.6	83.7
Service costs	4.3	4.3	$ 4.2
Interest costs	3.5	1.8	1.4
Actuarial loss (gain)	3.2	(15.8)
Benefits and expenses paid	(6.2)	(6.4)
Curtailment loss - discontinued operations	0.4	0.0	0.0
Benefit obligation at end of year	72.8	67.6	83.7
Change in plan assets
Fair value of plan assets at beginning of year	131.5	169.9
Actual return (loss) on plan assets	22.6	(32.0)
Benefits and expenses paid	(6.2)	(6.4)
Fair value of plan assets at end of year	147.9	131.5	169.9
Funded (underfunded) status of the plans	75.1	63.9
Funded (underfunded) status of the plans
Pension assets	75.1	63.9
Other current liabilities	0.0	0.0
Other long-term liabilities	0.0	0.0
Asset (liability), defined benefit plan	75.1	63.9
Amounts recognized in Accumulated other comprehensive loss
Net actuarial loss	26.8	39.9
Net prior service cost	0.1	0.1
Accumulated other comprehensive loss	26.9	40.0
Postretirement Benefits
Change in benefit obligation
Benefit obligation at beginning of year	5.2	6.9
Service costs	0.0	0.0	0.0
Interest costs	0.3	0.1	0.1
Actuarial loss (gain)	0.2	(0.8)
Benefits and expenses paid	(0.7)	(1.0)
Curtailment loss - discontinued operations	0.0	0.0	0.0
Benefit obligation at end of year	5.0	5.2	6.9
Change in plan assets
Fair value of plan assets at beginning of year	3.6	4.5
Actual return (loss) on plan assets	0.5	0.1
Benefits and expenses paid	(0.7)	(1.0)
Fair value of plan assets at end of year	3.4	3.6	$ 4.5
Funded (underfunded) status of the plans	(1.6)	(1.6)
Funded (underfunded) status of the plans
Pension assets	0.0	0.0
Other current liabilities	0.0	0.0
Other long-term liabilities	1.6	1.6
Asset (liability), defined benefit plan	(1.6)	(1.6)
Amounts recognized in Accumulated other comprehensive loss
Net actuarial loss	2.0	2.4
Net prior service cost	0.0	0.0
Accumulated other comprehensive loss	$ 2.0	$ 2.4