FAIR VALUE MEASUREMENTS: Fair Value Measurements Level 4 (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, All Levels Transfers, Amount		$ 0	$ 0
Money market funds	[1]	64,173,000	97,833,000
Asset derivatives		405,000	3,655,000
Equity Securities, FV-NI		42,738,000	36,488,000
Liability derivatives		846,000	974,000
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	[1]	64,173,000	97,833,000
Asset derivatives		392,000	3,655,000
Equity Securities, FV-NI		42,738,000	36,488,000
Liability derivatives		814,000	870,000
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	[1]	0	0
Asset derivatives		13,000	0
Equity Securities, FV-NI		0	0
Liability derivatives		32,000	104,000
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	[1]	0	0
Asset derivatives		0	0
Equity Securities, FV-NI		0	0
Liability derivatives		0	0
Idaho Power Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds		26,510,000	79,228,000
Idaho Power Company | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds		26,510,000	79,228,000
Idaho Power Company | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds		0	0
Idaho Power Company | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds		$ 0	$ 0

[1] Holding company only. Does not include amounts held by Idaho Power.