BUSINESS SEGMENTS - Revenue From Major Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 879,654	$ 829,424	$ 734,159
Southern California Public Power
Disaggregation of Revenue [Line Items]
Revenues	$ 181,120	$ 181,656	$ 157,663
Percentage of revenues	20.60%	21.20%	21.50%
Sierra Pacific Power Company and Nevada Power Company
Disaggregation of Revenue [Line Items]
Revenues	$ 133,108	$ 116,797	$ 124,116
Percentage of revenues	15.10%	14.10%	16.90%
KPLC
Disaggregation of Revenue [Line Items]
Revenues	$ 114,066	$ 109,217	$ 105,837
Percentage of revenues	13.00%	13.20%	14.40%