Employee Benefit Plans and Other Postretirement Benefits - Change in Benefit Obligations and Change in Fair Value of Plan Assets Related to Pension and Postretirement Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		$ 0.0
Company contributions		25.0	$ 25.0	$ 50.0
Fair value of plan assets at plan year end		0.0	0.0
Amounts Recognized on Consolidated Balance Sheets:
Noncurrent liabilities		(106.2)	(95.9)
Pension Plans
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		1,118.7	1,202.1
Service cost		10.3	12.3	14.1
Interest cost		57.0	55.3	55.8
Plan amendments		1.6	2.7
Actuarial (gain) loss (a)	[1]	24.9	(89.8)
Participant contributions		0.0	0.0
Benefits paid		(68.0)	(63.9)
Benefit obligation at plan year end		1,144.5	1,118.7	1,202.1
Accumulated benefit obligation portion of above		1,130.8	1,098.7
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		1,133.4	1,161.6
Actual return on plan assets		88.4	9.5
Company contributions		1.3	26.2
Participant contributions		0.0	0.0
Benefits paid		(68.0)	(63.9)
Fair value of plan assets at plan year end		1,155.1	1,133.4	1,161.6
Overfunded (underfunded) status		10.6	14.7
Amounts Recognized on Consolidated Balance Sheets:
Noncurrent assets		62.2	63.3
Current liabilities		(3.5)	(2.7)
Noncurrent liabilities		(48.1)	(45.9)
Accrued asset (obligation) recognized at December 31		10.6	14.7
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax):
Prior service credit		22.4	26.4
Actuarial gain		80.8	81.8
Total		103.2	108.2
Postretirement Plans
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		10.1	10.5
Service cost		0.2	0.2	0.2
Interest cost		0.5	0.5	0.5
Plan amendments		0.0	0.0
Actuarial (gain) loss (a)	[1]	2.1	0.2
Participant contributions		0.4	0.4
Benefits paid		(1.6)	(1.7)
Benefit obligation at plan year end		11.7	10.1	10.5
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		(0.0)	0.0
Actual return on plan assets		0.0	0.0
Company contributions		1.2	1.3
Participant contributions		0.4	0.4
Benefits paid		(1.6)	(1.7)
Fair value of plan assets at plan year end		0.0	(0.0)	$ 0.0
Overfunded (underfunded) status		(11.7)	(10.1)
Amounts Recognized on Consolidated Balance Sheets:
Noncurrent assets		0.0	0.0
Current liabilities		(0.9)	(0.5)
Noncurrent liabilities		(10.8)	(9.6)
Accrued asset (obligation) recognized at December 31		(11.7)	(10.1)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax):
Prior service credit		(3.0)	(3.4)
Actuarial gain		(2.0)	(4.3)
Total		$ (5.0)	$ (7.7)

[1] For the year ended December 31, 2025, the most significant driver of the increase in the aggregate benefit obligations for the pension and OPEB plans was the actuarial loss due to a decrease in the discount rate assumption. Additional losses were experienced due to updated benefit multipliers in the PCA Hourly Pension Plan, assumption changes resulting from the 2025 experience study, and updated claims and trend assumptions for the Retiree Medical plan. For the year ended December 31, 2024, the most significant driver of the decrease in the aggregate benefit obligations for the pension and OPEB plans was the actuarial gain due to an increase in the discount rate assumption. Additional gains due to participant experience and the decrease in the salary scale were offset by actuarial losses due to increases in the PCA Hourly Pension Plan benefit multipliers and updated medical assumptions to better reflect anticipated future experience.