Benefit Plans: (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Amounts charged to expense for defined contribution plans	$ 158	$ 123	$ 111
Estimated contribution to pension plans	164
Net postemployment costs	$ 250	$ 238	213
Postemployment weighted-average discount rate	4.90%	4.90%
Postemployment annual weighted-average turnover rate	2.90%	2.90%
Postemployment percentage increase in assumed compensation cost	2.20%	2.30%
Assets related to postemployment cost	$ 30	$ 30
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	55.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	45.00%
Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 10,600	9,900
Accumulated benefit obligations in excess of plan assets, accumulated benefit obligation	8,400	7,700
Accumulated benefit obligations in excess of plan assets, fair value of plan assets	7,600	6,200
Projected benefit obligations in excess of plan assets, project benefit obligation	8,800	8,200
Projected benefit obligations in excess of plan assets, fair value of plan assets	7,600	6,200
Accrued postemployment costs	11,134	10,456	$ 10,567
Post- employment
Defined Benefit Plan Disclosure [Line Items]
Accrued postemployment costs	$ 1,036	$ 929
Pension Plan Portfolio | Benefit Obligation | Switzerland:
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage	71.00%	69.00%
Pension Plan Portfolio | Benefit Obligation | United States
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage	5.00%	6.00%
Pension Plan Portfolio | Fair Value Of Plan Assets | Switzerland:
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage	65.00%	63.00%
Pension Plan Portfolio | Fair Value Of Plan Assets | United States
Defined Benefit Plan Disclosure [Line Items]
Concentration risk percentage	5.00%	6.00%