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Capitalization (Tables)
3 Months Ended
Mar. 31, 2023
Capitalization [Abstract]  
Schedule of carrying amount and fair value of the bonds
   (Thousands of Dollars)
   March 31, 2023  December 31, 2022
   Carrying  Fair  Carrying  Fair
   Amount  Value  Amount  Value
FMBs  $146,496   $137,983   $147,269   $138,756