Accumulated Other Comprehensive Income (Loss) - After-tax Changes by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (123)	$ (152)	$ (124)	$ (157)
Amounts arising during the period	(15)	22	(14)	22
Reclassifications from AOCI	1	6	1	11
Net OCI during the period	(14)	28	(13)	33
Balance at end of period	(137)	(124)	(137)	(124)
Unrealized gains (losses) on qualifying derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	4	2	3	1
Amounts arising during the period	0	0	0	0
Reclassifications from AOCI	0	0	1	1
Net OCI during the period	0	0	1	1
Balance at end of period	4	2	4	2
Defined benefit plans Prior service costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(5)	(6)	(5)	(6)
Amounts arising during the period	0	0	0	(1)
Reclassifications from AOCI	1	0	1	1
Net OCI during the period	1	0	1	0
Balance at end of period	(4)	(6)	(4)	(6)
Defined benefit plans Actuarial gain (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(125)	(149)	(124)	(152)
Amounts arising during the period	(15)	21	(15)	21
Reclassifications from AOCI	0	6	(1)	9
Net OCI during the period	(15)	27	(16)	30
Balance at end of period	(140)	(122)	(140)	(122)
Equity Investees' OCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	3	1	2	0
Amounts arising during the period	0	1	1	2
Reclassifications from AOCI	0	0	0	0
Net OCI during the period	0	1	1	2
Balance at end of period	$ 3	$ 2	$ 3	$ 2