Accumulated Other Comprehensive Loss (Changes in Accumulated Other Comprehensive Loss by Component) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		$ (131)	$ 2	$ (67)
Other comprehensive income (loss) before reclassifications, net of tax		52	(79)	58
Amounts reclassified from accumulated other comprehensive loss:
Amortization of prior service cost (credit)		(55)	(67)	(67)
Amortization of actuarial loss		6	(5)	10
Settlement (gain) loss		3	(1)	79
Other			(1)
Tax effect		11	20	(11)
Other comprehensive income (loss)		17	(133)	69
Ending balance		(114)	(131)	2
Other comprehensive income (loss) before reclassifications, tax		16	(22)	11
Pension Benefits
Amounts reclassified from accumulated other comprehensive loss:
Amortization of prior service cost (credit)		(33)	(45)	(45)
Other Benefits
Amounts reclassified from accumulated other comprehensive loss:
Amortization of prior service cost (credit)		(22)	(22)	(22)
Accumulated Defined Benefit Plans Adjustment | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(261)	(163)	(117)
Other comprehensive income (loss) before reclassifications, net of tax		44	(60)	(70)
Amounts reclassified from accumulated other comprehensive loss:
Amortization of prior service cost (credit)	[1]	(33)	(45)	(45)
Amortization of actuarial loss	[1]	6	(5)	4
Settlement (gain) loss	[1]	3	(1)	79
Tax effect		6	13	(14)
Other comprehensive income (loss)		26	(98)	(46)
Ending balance		(235)	(261)	(163)
Accumulated Defined Benefit Plans Adjustment | Other Benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		129	165	49
Other comprehensive income (loss) before reclassifications, net of tax		10	(21)	129
Amounts reclassified from accumulated other comprehensive loss:
Amortization of prior service cost (credit)	[1]	(22)	(22)	(22)
Amortization of actuarial loss	[1]	0	0	6
Settlement (gain) loss	[1]	0	0	0
Tax effect		5	7	3
Other comprehensive income (loss)		(7)	(36)	116
Ending balance		122	129	165
Other
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		1	0	1
Other comprehensive income (loss) before reclassifications, net of tax		(2)	2	(1)
Amounts reclassified from accumulated other comprehensive loss:
Other			(1)
Tax effect		0	0	0
Other comprehensive income (loss)		(2)	1	(1)
Ending balance		$ (1)	$ 1	$ 0

[1] These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 24.