Accumulated Other Comprehensive Income AOCI by Component (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Beginning Balance	$ 194	$ 353
Other comprehensive income (loss), net before reclassifications	(1)	11
Reclassification from AOCI, Current Period, Tax	6	(1)
Ending Balance	173	367
Equity Method Investments
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Beginning Balance	9	(3)
Other comprehensive income (loss), net before reclassifications	(1)	11
Reclassification from AOCI, Current Period, Tax	0	0
Ending Balance	8	8
Pension and Retiree Health and Welfare Benefit Items
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Beginning Balance	185	356
Other comprehensive income (loss), net before reclassifications	0	0
Reclassification from AOCI, Current Period, Tax	6	(1)
Ending Balance	165	359
Amortization of net loss
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amortization of actuarial losses	(26)	4
Amortization of net loss | Equity Method Investments
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amortization of actuarial losses	0	0
Amortization of net loss | Pension and Retiree Health and Welfare Benefit Items
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]
Amortization of actuarial losses	$ (26)	$ 4