v3.24.0.1
Income Taxes: (Schedule of Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits [Roll Forward]      
Beginning balance $ 72 $ 89 $ 72
Additions based on tax positions related to the current year 7 12 12
Additions for tax positions of previous years 1 2 15
Reductions for tax positions of prior years (23) (18) (1)
Reductions due to lapse of statute of limitations (3) (6) (3)
Settlements 0 (4) 0
Other 1 (3) (6)
Ending balance $ 55 $ 72 $ 89