Accumulated Other Comprehensive Income Reclassifications out of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Balance	$ 98	$ 145	$ 130
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	251	(47)	15
Reclassification AOCI, Tax	(1)	(1)	(1)
Balance	353	98	145
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	81	(17)	4
Amortization of net gain
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income	6
Amortization of prior service credits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income		2	(4)
Settlement (gain) lossa
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income	(1)	(1)	5
Equity Method Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Balance	(3)	(4)	(3)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	1	(1)
Reclassification AOCI, Tax	0	0	0
Balance	(3)	(3)	(4)
Equity Method Investments | Amortization of net gain
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income	0
Equity Method Investments | Amortization of prior service credits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income		0	0
Equity Method Investments | Settlement (gain) lossa
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income	0	0	0
Pension and Retiree Health and Welfare Benefit Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Balance	101	149	133
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	251	(48)	16
Reclassification AOCI, Tax	(1)	(1)	(1)
Balance	356	101	149
Pension and Retiree Health and Welfare Benefit Items | Amortization of net gain
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income	6
Pension and Retiree Health and Welfare Benefit Items | Amortization of prior service credits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income		2	(4)
Pension and Retiree Health and Welfare Benefit Items | Settlement (gain) lossa
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income	$ (1)	$ (1)	$ 5