Benefit Plans: (Obligations and Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Employer contributions, net of refunds	$ (139)	$ (110)	$ (21)
Pension
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning balance	10,456	10,567
Service cost	240	218	174
Interest cost	209	234	258
Benefits paid	(567)	(434)
Employee contributions	168	157
Settlement, curtailment and plan amendment	(32)	(12)
Actuarial losses (gains)	(640)	460
Currency	1,317	(708)
Other	(17)	(26)
Benefit obligation, ending balance	11,134	10,456	10,567
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning balance	9,030	8,851
Actual return on plan assets	882	973
Employer contributions, net of refunds	139	110
Employee contributions	168	157
Benefits paid	(567)	(434)
Settlement	(18)	(10)
Currency	1,182	(600)
Other	0	(17)
Fair value of plan assets, ending balance	10,816	9,030	8,851
Net benefit liability	(318)	(1,426)
Post- retirement
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning balance	248	246
Service cost	4	3	4
Interest cost	12	13	12
Benefits paid	(13)	(14)
Employee contributions	0	0
Settlement, curtailment and plan amendment	0	(1)
Actuarial losses (gains)	11	2
Currency	4	5
Other	(3)	(6)
Benefit obligation, ending balance	263	248	246
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, beginning balance	3	3
Actual return on plan assets	0	0
Employer contributions, net of refunds	13	14
Employee contributions	0	0
Benefits paid	(13)	(14)
Settlement	0	(1)
Currency	0	1
Other	0	0
Fair value of plan assets, ending balance	3	3	$ 3
Net benefit liability	$ (260)	$ (245)