v3.25.0.1
Income Taxes: (Schedule of Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits [Roll Forward]      
Beginning balance $ 55 $ 72 $ 89
Additions based on tax positions related to the current year 6 7 12
Additions for tax positions of previous years 1 1 2
Reductions for tax positions of prior years 0 (23) (18)
Reductions due to lapse of statute of limitations (2) (3) (6)
Settlements 0 0 (4)
Other (4) 1 (3)
Ending balance $ 56 $ 55 $ 72