Benefit Plans: (Pension and Postretirement Liabilities Recognized in Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other assets	$ 926	$ 490
Accrued liabilities — employment costs	(29)	(33)
Long-term employment costs	(1,215)	(1,883)
Net benefit liability	(318)	(1,426)
Post- retirement
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other assets
Accrued liabilities — employment costs	(16)	(14)
Long-term employment costs	(244)	(231)
Net benefit liability	$ (260)	$ (245)