Benefit Plans: (Movements in Other Comprehensive Earnings (Losses)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amortization:
Net losses (gains)	$ 227	$ 175	$ 96
Prior service cost (credit)	(6)	(6)	7
Other income/expense:
Net losses (gains)	2	2	12
Prior service cost (credit)	(2)
Deferred income taxes	(46)	(36)	(28)
Amortization of net losses, prior service costs and net transition costs	175	135	87
Other movements during the year:
Deferred income taxes	(176)	8	182
Net gains (losses) and prior service costs	884	(10)	(861)
Total accumulated other comprehensive losses
Other movements during the year:
Net (losses) gains	1,056	(19)	(1,035)
Prior service (cost) credit	1	4
Deferred income taxes	(176)	8	181
Net gains (losses) and prior service costs	881	(7)	(854)
Total movements in other comprehensive earnings (losses)	1,056	128	(767)
Pension
Amortization:
Net losses (gains)	145	88	19
Prior service cost (credit)	(6)	(6)	7
Other income/expense:
Net losses (gains)	2	1	11
Prior service cost (credit)	(2)
Deferred income taxes	(26)	(13)	(9)
Amortization of net losses, prior service costs and net transition costs	113	70	28
Other movements during the year:
Net (losses) gains	1,087	114	(918)
Prior service (cost) credit	1	4
Deferred income taxes	(184)	(24)	154
Net gains (losses) and prior service costs	904	94	(764)
Total movements in other comprehensive earnings (losses)	1,017	164	(736)
Post- retirement
Amortization:
Net losses (gains)	3	1	1
Prior service cost (credit)	0	0	0
Other income/expense:
Net losses (gains)	1	1	1
Prior service cost (credit)	0
Deferred income taxes	(1)	(2)	(1)
Amortization of net losses, prior service costs and net transition costs	3	0	1
Other movements during the year:
Net (losses) gains	(11)	(2)	(24)
Prior service (cost) credit	0	0
Deferred income taxes	3	2	6
Net gains (losses) and prior service costs	(8)	0	(18)
Total movements in other comprehensive earnings (losses)	(5)	0	(17)
Post- employment
Amortization:
Net losses (gains)	79	86	76
Prior service cost (credit)	0	0	0
Other income/expense:
Net losses (gains)	(1)	0	0
Prior service cost (credit)	0
Deferred income taxes	(19)	(21)	(18)
Amortization of net losses, prior service costs and net transition costs	59	65	58
Other movements during the year:
Net (losses) gains	(20)	(131)	(93)
Prior service (cost) credit	0	0
Deferred income taxes	5	30	21
Net gains (losses) and prior service costs	(15)	(101)	(72)
Total movements in other comprehensive earnings (losses)	$ 44	$ (36)	$ (14)