Accumulated Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 652.2	$ 631.2
Other comprehensive loss, net of tax		(2.1)	(1.1)
Ending balance		664.9	635.6
Defined Benefit Plans:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		11.0	2.8
Less: income tax benefit (expense)	[1]	0.1	(0.2)
Other comprehensive loss, net of tax		(0.5)	0.7
Ending balance		10.5	3.5
Defined Benefit Plans: Net Actuarial Gain
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of unrealized loss upon settlement of cash flow hedges	[2]	(0.3)	(0.3)
Defined Benefit Plans: Net Prior Service (Credit) Cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of unrealized loss upon settlement of cash flow hedges	[2]	(0.3)	1.2
Cash Flow Hedges:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		2.1	0.4
Unrealized loss on cash flow hedges		(4.2)	(2.6)
Less: income tax benefit		1.0	0.6
Net unrealized loss on cash flow hedges		(3.2)	(2.0)
Reclassification of unrealized loss upon settlement of cash flow hedges		2.1	0.2
Less: income tax benefit (expense)		(0.5)
Net loss reclassified from AOCI to Net income		1.6	0.2
Other comprehensive loss, net of tax		(1.6)	(1.8)
Ending balance	[3]	0.5	(1.4)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		13.1	3.2
Other comprehensive loss, net of tax		(2.1)	(1.1)
Ending balance		$ 11.0	$ 2.1

[1] Income tax amounts reclassified out of AOCI were included as a component of Income tax provision.

[2] Amounts amortized out of AOCI related to pension and other postretirement benefits were included within Net periodic postretirement benefit cost (see Note 3).

[3] As of March 31, 2024, we estimate a net mark-to-market gain before tax of $0.5 million in AOCI will be reclassified into Net income upon settlement within the next 12 months.