Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities:
Net Income	$ 233,328	$ 227,523	$ 213,188
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	173,800	169,120	165,933
Deferred income taxes and investment tax credits	22,389	11,292	33,245
Changes in regulatory assets and liabilities	(4,310)	48,392	57,131
Pension and postretirement benefit plan expense	27,804	32,256	28,911
Contributions to pension and postretirement benefit plans	(48,525)	(45,899)	(46,589)
Earnings of unconsolidated equity-method investments	(12,370)	(12,449)	(11,374)
Distributions from unconsolidated equity-method investments	21,800	31,115	24,975
Allowance for equity funds used during construction	(27,112)	(24,353)	(20,784)
Gain on sale of investments and assets	(285)	(155)	(131)
Other non-cash adjustments to net income, net	8,325	9,152	8,454
Change in:
Accounts receivable	(5,996)	729	1,045
Accounts payable and other accrued liabilities	(9,526)	29,666	(17,208)
Taxes accrued/receivable	742	4,725	4,361
Other current assets	(8,820)	12,707	2,814
Other current liabilities	(799)	6,848	1,017
Other assets	(4,375)	(7,488)	(8,734)
Other liabilities	555	(1,555)	(1,093)
Net cash provided by operating activities	366,625	491,626	435,161
Investing Activities:
Additions to property, plant and equipment	(278,705)	(277,853)	(285,488)
Payments received from transmission project joint funding partners	2,442	21,587	6,074
Purchase of available-for-sale securities	(10,896)	(11,390)	(11,356)
Proceeds from sale of available-for-sale securities	5,080	5,007	4,989
Other	1,587	4,472	5,340
Net cash used in investing activities	(280,492)	(258,177)	(280,441)
Financing Activities:
Issuance of long-term debt	166,100	220,000	0
Retirement of long-term debt	(166,100)	(130,000)	(1,064)
Dividends on common stock	(129,677)	(121,421)	(113,127)
Dividends, Common Stock, Cash	129,872	121,786	113,181
Net change in short-term borrowings	0	0	(21,800)
Acquisition of treasury stock	(4,160)	(3,614)	(3,212)
Make-whole premium on retirement of long-term debt	0	(4,607)	0
Other	(2,534)	(2,964)	(348)
Net cash used in financing activities	(136,371)	(42,606)	(139,551)
Net increase (decrease) in cash and cash equivalents	(50,238)	190,843	15,169
Cash and cash equivalents at beginning of the year	267,492	76,649	61,480
Cash and cash equivalents at end of the year	217,254	267,492	76,649
Cash paid during the period for:
Income taxes	14,055	5,272	14,742
Interest (net of amount capitalized)	85,260	80,951	80,004
Non-cash investing activities:
Additions to property, plant and equipment in accounts payable	38,815	29,528	33,220
Idaho Power Company
Operating Activities:
Net Income	224,437	222,334	206,347
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	173,205	168,519	165,337
Deferred income taxes and investment tax credits	14,889	(2,272)	(10,875)
Changes in regulatory assets and liabilities	(4,310)	48,392	57,131
Pension and postretirement benefit plan expense	27,788	32,240	28,894
Contributions to pension and postretirement benefit plans	(48,509)	(45,883)	(46,573)
Earnings of unconsolidated equity-method investments	(10,285)	(10,712)	(9,267)
Distributions from unconsolidated equity-method investments	19,450	29,400	23,000
Allowance for equity funds used during construction	(27,112)	(24,353)	(20,784)
Gain on sale of investments and assets	(285)	(155)	(131)
Other non-cash adjustments to net income, net	(463)	(210)	1,069
Change in:
Accounts receivable	(4,724)	633	(5,282)
Accounts payable and other accrued liabilities	(9,463)	(25,532)	38,111
Taxes accrued/receivable	2,281	15,509	(3,601)
Other current assets	(8,821)	12,707	2,812
Other current liabilities	(870)	6,822	996
Other assets	(4,280)	(7,488)	(8,734)
Other liabilities	584	(1,476)	(967)
Net cash provided by operating activities	343,512	418,475	417,483
Investing Activities:
Additions to property, plant and equipment	(278,707)	(277,823)	(285,471)
Payments received from transmission project joint funding partners	2,442	21,587	6,074
Purchase of available-for-sale securities	(10,896)	(11,390)	(11,356)
Proceeds from sale of available-for-sale securities	5,080	5,007	4,989
Other	4,117	4,320	5,176
Net cash used in investing activities	(277,964)	(258,299)	(280,588)
Financing Activities:
Issuance of long-term debt	166,100	220,000	0
Retirement of long-term debt	(166,100)	(130,000)	(1,064)
Dividends on common stock		(121,791)	(113,284)
Dividends, Common Stock, Cash	129,877	121,791	113,284
Net change in short-term borrowings	0	0	(21,800)
Make-whole premium on retirement of long-term debt	0	(4,607)	0
Other	(2,181)	(2,964)	(241)
Net cash used in financing activities	(132,058)	(39,362)	(136,389)
Net increase (decrease) in cash and cash equivalents	(66,510)	120,814	506
Cash and cash equivalents at beginning of the year	165,460	44,646	44,140
Cash and cash equivalents at end of the year	98,950	165,460	44,646
Cash paid during the period for:
Income taxes	19,856	63,914	12,444
Interest (net of amount capitalized)	85,198	80,894	79,918
Non-cash investing activities:
Additions to property, plant and equipment in accounts payable	$ 38,815	$ 29,528	$ 33,220