Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended								9 Months Ended
		Sep. 30, 2023		Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022		Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023		Sep. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 638.1		$ 635.6	$ 631.2	$ 650.0		$ 708.2	$ 692.5	$ 631.2		$ 692.5
Other comprehensive income (loss), net of tax		6.0		(7.3)	(1.1)	(0.4)		(35.6)	18.0	(2.4)		(18.0)
Ending balance		640.7		638.1	635.6	642.0		650.0	708.2	640.7		642.0
Defined Benefit Plans:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(1.1)			2.8	(19.6)			(21.4)	2.8		(21.4)
Less: income tax (expense) benefit	[1]	(0.3)				(0.2)				(0.7)		(0.9)
Net loss (gain) reclassified from AOCI to Net income (loss)		0.8				1.0				2.4		2.8
Other comprehensive income (loss), net of tax		0.8				1.0				(3.1)		2.8
Ending balance		(0.3)		(1.1)		(18.6)		(19.6)		(0.3)		(18.6)
Defined Benefit Plans: Net Actuarial Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Unrealized (loss) gain on cash flow hedges										(0.6)
Less: income tax benefit										0.1
Net unrealized (loss) gain on cash flow hedges										(0.5)
Reclassification of unrealized loss (gain) upon settlement of cash flow hedges	[2]	(0.3)								(0.9)
Defined Benefit Plans: Net Prior Service Cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Unrealized (loss) gain on cash flow hedges										(6.6)
Less: income tax benefit										1.6
Net unrealized (loss) gain on cash flow hedges										(5.0)
Reclassification of unrealized loss (gain) upon settlement of cash flow hedges	[2]	1.4				1.2				4.0		3.7
Cash Flow Hedges:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(4.1)			0.4	(1.7)			17.7	0.4		17.7
Unrealized (loss) gain on cash flow hedges		2.4				(9.8)				(9.2)		(18.2)
Less: income tax benefit		(0.6)				2.2				2.1		4.2
Net unrealized (loss) gain on cash flow hedges		1.8				(7.6)				(7.1)		(14.0)
Reclassification of unrealized loss (gain) upon settlement of cash flow hedges		4.5				8.1				10.2		(8.9)
Less: income tax (expense) benefit	[1]	(1.1)				(1.9)				(2.4)		2.1
Net loss (gain) reclassified from AOCI to Net income (loss)		3.4				6.2				7.8		(6.8)
Other comprehensive income (loss), net of tax		5.2				(1.4)				0.7		(20.8)
Ending balance		1.1	[3]	(4.1)		(3.1)	[3]	(1.7)		1.1	[3]	(3.1)	[3]
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(5.2)		2.1	3.2	(21.3)		14.3	(3.7)	3.2		(3.7)
Other comprehensive income (loss), net of tax		6.0		(7.3)	(1.1)	(0.4)		(35.6)	18.0
Ending balance		$ 0.8		$ (5.2)	$ 2.1	$ (21.7)		$ (21.3)	$ 14.3	$ 0.8		$ (21.7)

[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 September 30, 2023, we estimate a net mark-to-market gain before tax of $1.0 million in AOCI will be reclassified into Net income (loss) upon settlement within the next 12 months.