OTHER INCOME AND EXPENSE Other Income and Expense Level 4 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Schedule of other nonoperating income (expense) [Line Items]
Interest and dividend income, net	$ 8,181	$ 5,605		$ 3,872
Carrying charges on regulatory assets	5,494	4,075		2,310
Net periodic benefit cost	10,976	15,781	[1]	11,194
Income from life insurance investments	4,104	2,779		2,090
Other Expense	(301)
Other Income		455		813
Other (expense) income, net	6,502	(2,867)		(2,109)
Idaho Power Company
Schedule of other nonoperating income (expense) [Line Items]
Interest and dividend income, net	5,898	4,688		3,787
Carrying charges on regulatory assets	5,494	4,075		2,310
Net periodic benefit cost	10,976	15,781	[1]	11,194
Income from life insurance investments	4,104	2,779		2,090
Other Expense	(2,254)	(1,612)		(1,749)
Other (expense) income, net	$ 2,266	$ (5,851)		$ (4,756)

[1] The 2018 pension and postretirement non-service costs includes $4.2 million of expense for a temporary deviation from the cost-sharing provisions of the substantive postretirement plan as described in Note 12 - "Benefit Plans."