v3.25.1
Capitalization (Tables)
3 Months Ended
Mar. 31, 2025
Capitalization [Abstract]  
Schedule of Carrying Amount and Fair Value of First Mortgage Bonds (FMBs) The carrying amount and fair value of the FMBs were as follows:
    (Thousands of Dollars)
    March 31, 2025   December 31, 2024
    Carrying   Fair   Carrying   Fair
    Amount   Value   Amount   Value
FMBs   $ 128,857     $ 124,031     $ 129,602     $ 125,067