Accumulated Other Comprehensive Income Reclassifications out of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	$ 19	$ 115	$ 21
Total
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Balance	581	234	194
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(62)	362	67
Reclassification AOCI, Amortization of actuarial (gains)/losses	(30)	(20)	(36)
Reclassification AOCI, Settlement (gain)/loss	2
Reclassification AOCI, Tax	7	5	9
Balance	498	581	234
Equity Method Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Balance	9	8	9
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	1	(1)
Reclassification AOCI, Amortization of actuarial (gains)/losses	0	0	0
Reclassification AOCI, Settlement (gain)/loss	0
Reclassification AOCI, Tax	0	0	0
Balance	9	9	8
Pension and Retiree Health and Welfare Benefit Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Balance	572	226	185
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(62)	361	68
Reclassification AOCI, Amortization of actuarial (gains)/losses	(30)	(20)	(36)
Reclassification AOCI, Settlement (gain)/loss	2
Reclassification AOCI, Tax	7	5	9
Balance	$ 489	$ 572	$ 226