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Business Description And Significant Accounting Policies: Materials, Supplies and Fuel (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Inventory, Net [Abstract]    
Materials and supplies $ 85,250 $ 82,809
Fuel 1,531 2,425
Natural gas in storage 30,619 31,938
Total materials, supplies and fuel $ 117,400 $ 117,172