Accumulated Other Comprehensive Income (Loss) - After-tax Changes by Component (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (184)	$ (163)
Amounts arising during the period		1
Reclassifications from AOCI	0	1
Net OCI during the period	0	2
Balance at end of period	(184)	(161)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(3)	(4)
Amounts arising during the period		0
Reclassifications from AOCI	0	0
Net OCI during the period	0	0
Balance at end of period	(3)	(4)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(194)	(168)
Amounts arising during the period		0
Reclassifications from AOCI	(1)	0
Net OCI during the period	(1)	0
Balance at end of period	(195)	(168)
Equity Investees' OCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	4	3
Amounts arising during the period		1
Reclassifications from AOCI	0	0
Net OCI during the period	0	1
Balance at end of period	4	4
Unrealized gains (losses) on qualifying derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	9	6
Amounts arising during the period		0
Reclassifications from AOCI	1	1
Net OCI during the period	1	1
Balance at end of period	$ 10	$ 7