Pensions and Other Postretirement Benefits - Narrative (Details) $ in Millions	5 Months Ended	12 Months Ended
	May 31, 2024 USD ($) employee	Dec. 31, 2025 USD ($) investment_firm	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan's accumulated benefit obligation		$ 1,900	$ 1,900
Unfunded pension plans projected benefit obligation		277	273
Unfunded pension plans accumulated benefit obligations		$ 265	256
Number of investment firms | investment_firm		8
Multiemployer plan, contributions by employer		$ 6	9	$ 11
Defined contribution plan, cost		26	25	25
Employee Severance
Defined Benefit Plan Disclosure [Line Items]
Number of management employees separated from service | employee	350
Level 2
Defined Benefit Plan Disclosure [Line Items]
Trust-owned life insurance fair value		$ 156	$ 145
Minimum
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets target allocation for equity		50.00%	50.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets target allocation for equity		65.00%	65.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation, by asset category		35.00%	35.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain	$ 0
Estimated net loss for defined pension plans amortized from AOCI into net periodic cost		$ 17
Assumed increases in per capita cost of covered health care benefits		6.50%
Ultimate health care cost trend rate		5.00%
Pension plan assets target allocation for equity		75.00%
Assumed rate of return on pension plan assets		8.00%
Expected contribution for the next fiscal year		$ 23
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain		0	$ 20	$ 0
Defined benefit plan, increase (decrease) in future years of service for plan participants, curtailment	10.00%
Defined benefit plan, future amortization of prior service cost (credit)		23
Expected contribution for the next fiscal year		$ 34
Other Postretirement Benefits | Defined Benefit Plan, Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation, by asset category		65.00%	65.00%