Electric utility segment - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Utility property, plant and equipment
Total property, plant and equipment, net	$ 6,183,503	$ 6,150,126
Current assets
Cash and cash equivalents	485,192	679,546	$ 315,334
Restricted cash	17,531	15,028	4,216
Other long-term assets
Operating lease right-of-use assets	91,182	94,905
Total assets	16,923,208	17,243,821
Capitalization
Common stock equity	2,377,380	2,344,841	2,237,955	$ 2,202,499
Preferred stock of subsidiaries - not subject to mandatory redemption	34,293	34,293
Current liabilities
Interest and dividends payable	61,452	51,206
Deferred credits and other liabilities
Deferred income taxes	299,012	297,954
Total liabilities and shareholders’ equity	16,923,208	17,243,821
Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	52,019	52,098
Plant and equipment	8,302,449	8,232,810
Financing lease right-of-use assets	354,401	342,174
Less accumulated depreciation	(3,249,089)	(3,197,514)
Construction in progress	330,743	320,223
Utility property, plant and equipment, net	5,790,523	5,749,791
Nonutility property, plant and equipment, less accumulated depreciation	6,941	6,942
Total property, plant and equipment, net	5,797,464	5,756,733
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	129,754	106,077	116,022
Restricted cash	2,000	2,000	0
Advances to affiliates	0	0
Customer accounts receivable, net	209,999	244,309
Accrued unbilled revenues, net	171,455	185,644
Other accounts receivable, net	38,025	111,519
Fuel oil stock, at average cost	161,433	148,237
Materials and supplies, at average cost	115,719	114,433
Prepayments and other	72,025	58,491
Regulatory assets	82,503	68,453
Total current assets	982,913	1,039,163
Other long-term assets
Operating lease right-of-use assets	68,217	71,877
Regulatory assets	232,564	226,351
Other	193,704	189,430
Total other long-term assets	494,485	487,658
Total assets	7,274,862	7,283,554
Capitalization
Common stock equity	2,435,282	2,409,110	2,358,884	2,344,170
Preferred stock of subsidiaries - not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,886,028	1,934,277
Total capitalization	4,355,603	4,377,680
Current liabilities
Current portion of operating lease liabilities	16,234	16,617
Current portion of long-term debt	46,931	0
Accounts payable	198,636	191,040
Interest and dividends payable	43,926	22,882
Taxes accrued, including revenue taxes	282,446	291,942
Regulatory liabilities	26,149	36,559
Other	108,006	171,436
Total current liabilities	722,328	730,476
Deferred credits and other liabilities
Operating lease liabilities	58,399	62,098
Finance lease liabilities	341,141	330,978
Deferred income taxes	403,761	399,001
Regulatory liabilities	1,133,662	1,114,131
Unamortized tax credits	81,771	84,312
Defined benefit pension and other postretirement benefit plans liability	62,331	60,671
Other	115,866	124,207
Total deferred credits and other liabilities	2,196,931	2,175,398
Total liabilities and shareholders’ equity	7,274,862	7,283,554
Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	0	0
Consolidating adjustments | Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	0	0
Plant and equipment	0	0
Financing lease right-of-use assets	0	0
Less accumulated depreciation	0	0
Construction in progress	0	0
Utility property, plant and equipment, net	0	0
Nonutility property, plant and equipment, less accumulated depreciation	0	0
Total property, plant and equipment, net	0	0
Investment in wholly owned subsidiaries, at equity	(728,222)	(722,211)
Current assets
Cash and cash equivalents	0	0	0
Restricted cash	0	0
Advances to affiliates	(93,000)	(70,500)
Customer accounts receivable, net	0	0
Accrued unbilled revenues, net	0	0
Other accounts receivable, net	(38,307)	(77,480)
Fuel oil stock, at average cost	0	0
Materials and supplies, at average cost	0	0
Prepayments and other	(1,434)	(1,638)
Regulatory assets	0	0
Total current assets	(132,741)	(149,618)
Other long-term assets
Operating lease right-of-use assets	0	0
Regulatory assets	0	0
Other	(14,484)	(14,171)
Total other long-term assets	(14,484)	(14,171)
Total assets	(875,447)	(886,000)
Capitalization
Common stock equity	(728,222)	(722,211)	(705,212)	(701,833)
Preferred stock of subsidiaries - not subject to mandatory redemption	0	0
Long-term debt, net	0	0
Total capitalization	(728,222)	(722,211)
Current liabilities
Current portion of operating lease liabilities	0	0
Current portion of long-term debt	0
Accounts payable	0	0
Interest and dividends payable	(547)	(375)
Taxes accrued, including revenue taxes	(1,434)	(1,638)
Regulatory liabilities	0	0
Other	(37,760)	(77,105)
Total current liabilities	(132,741)	(149,618)
Deferred credits and other liabilities
Operating lease liabilities	0	0
Finance lease liabilities	0	0
Deferred income taxes	0	0
Regulatory liabilities	0	0
Unamortized tax credits	0	0
Defined benefit pension and other postretirement benefit plans liability	(14,484)	(14,171)
Other	0	0
Total deferred credits and other liabilities	(14,484)	(14,171)
Total liabilities and shareholders’ equity	(875,447)	(886,000)
Consolidating adjustments | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	(93,000)	(70,500)
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	42,860	42,859
Plant and equipment	5,442,481	5,398,281
Financing lease right-of-use assets	318,326	306,099
Less accumulated depreciation	(1,962,980)	(1,925,660)
Construction in progress	249,111	247,836
Utility property, plant and equipment, net	4,089,798	4,069,415
Nonutility property, plant and equipment, less accumulated depreciation	5,294	5,295
Total property, plant and equipment, net	4,095,092	4,074,710
Investment in wholly owned subsidiaries, at equity	728,222	722,211
Current assets
Cash and cash equivalents	111,200	89,755	49,393
Restricted cash	2,000	2,000
Advances to affiliates	93,000	70,500
Customer accounts receivable, net	148,241	172,747
Accrued unbilled revenues, net	124,691	136,367
Other accounts receivable, net	47,107	143,160
Fuel oil stock, at average cost	121,468	108,228
Materials and supplies, at average cost	65,457	64,334
Prepayments and other	52,174	40,767
Regulatory assets	69,284	58,920
Total current assets	834,622	886,778
Other long-term assets
Operating lease right-of-use assets	33,628	34,856
Regulatory assets	194,038	189,417
Other	138,076	134,033
Total other long-term assets	365,742	358,306
Total assets	6,023,678	6,042,005
Capitalization
Common stock equity	2,435,282	2,409,110	2,358,884	2,344,170
Preferred stock of subsidiaries - not subject to mandatory redemption	22,293	22,293
Long-term debt, net	1,385,625	1,426,516
Total capitalization	3,843,200	3,857,919
Current liabilities
Current portion of operating lease liabilities	6,298	6,788
Current portion of long-term debt	39,941
Accounts payable	139,015	136,102
Interest and dividends payable	35,795	17,085
Taxes accrued, including revenue taxes	219,385	211,840
Regulatory liabilities	11,488	20,013
Other	81,609	165,131
Total current liabilities	533,531	556,959
Deferred credits and other liabilities
Operating lease liabilities	33,090	34,262
Finance lease liabilities	306,262	295,935
Deferred income taxes	283,734	280,029
Regulatory liabilities	817,663	803,404
Unamortized tax credits	59,188	61,130
Defined benefit pension and other postretirement benefit plans liability	76,815	74,842
Other	70,195	77,525
Total deferred credits and other liabilities	1,646,947	1,627,127
Total liabilities and shareholders’ equity	6,023,678	6,042,005
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	0	0
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	5,645	5,645
Plant and equipment	1,470,238	1,459,639
Financing lease right-of-use assets	36,075	36,075
Less accumulated depreciation	(673,926)	(666,581)
Construction in progress	36,013	33,488
Utility property, plant and equipment, net	874,045	868,266
Nonutility property, plant and equipment, less accumulated depreciation	115	115
Total property, plant and equipment, net	874,160	868,381
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	11,146	10,658	28,006
Restricted cash	0	0
Advances to affiliates	0	0
Customer accounts receivable, net	32,461	38,216
Accrued unbilled revenues, net	24,052	25,102
Other accounts receivable, net	7,619	13,318
Fuel oil stock, at average cost	15,596	17,968
Materials and supplies, at average cost	14,470	14,397
Prepayments and other	6,713	7,724
Regulatory assets	6,484	5,771
Total current assets	118,541	133,154
Other long-term assets
Operating lease right-of-use assets	25,733	27,470
Regulatory assets	14,050	13,575
Other	36,846	36,439
Total other long-term assets	76,629	77,484
Total assets	1,069,330	1,079,019
Capitalization
Common stock equity	364,177	359,790	346,629	344,720
Preferred stock of subsidiaries - not subject to mandatory redemption	7,000	7,000
Long-term debt, net	244,251	249,339
Total capitalization	615,428	616,129
Current liabilities
Current portion of operating lease liabilities	7,098	7,025
Current portion of long-term debt	4,992
Accounts payable	28,690	29,418
Interest and dividends payable	3,808	3,098
Taxes accrued, including revenue taxes	34,955	43,932
Regulatory liabilities	8,353	8,508
Other	27,837	33,240
Total current liabilities	115,733	125,221
Deferred credits and other liabilities
Operating lease liabilities	18,989	20,792
Finance lease liabilities	34,879	35,043
Deferred income taxes	51,699	51,661
Regulatory liabilities	202,178	199,173
Unamortized tax credits	11,351	11,650
Defined benefit pension and other postretirement benefit plans liability	0	0
Other	19,073	19,350
Total deferred credits and other liabilities	338,169	337,669
Total liabilities and shareholders’ equity	1,069,330	1,079,019
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	0	0
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	3,514	3,594
Plant and equipment	1,389,730	1,374,890
Financing lease right-of-use assets	0	0
Less accumulated depreciation	(612,183)	(605,273)
Construction in progress	45,619	38,899
Utility property, plant and equipment, net	826,680	812,110
Nonutility property, plant and equipment, less accumulated depreciation	1,532	1,532
Total property, plant and equipment, net	828,212	813,642
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	7,331	5,587	38,546
Restricted cash	0	0
Advances to affiliates	0	0
Customer accounts receivable, net	29,297	33,346
Accrued unbilled revenues, net	22,712	24,175
Other accounts receivable, net	21,606	32,521
Fuel oil stock, at average cost	24,369	22,041
Materials and supplies, at average cost	35,792	35,702
Prepayments and other	14,572	11,638
Regulatory assets	6,735	3,762
Total current assets	162,414	168,772
Other long-term assets
Operating lease right-of-use assets	8,856	9,551
Regulatory assets	24,476	23,359
Other	33,266	33,129
Total other long-term assets	66,598	66,039
Total assets	1,057,224	1,048,453
Capitalization
Common stock equity	363,968	362,344	358,506	357,036
Preferred stock of subsidiaries - not subject to mandatory redemption	5,000	5,000
Long-term debt, net	256,152	258,422
Total capitalization	625,120	625,766
Current liabilities
Current portion of operating lease liabilities	2,838	2,804
Current portion of long-term debt	1,998
Accounts payable	30,931	25,520
Interest and dividends payable	4,870	3,074
Taxes accrued, including revenue taxes	29,540	37,808
Regulatory liabilities	6,308	8,038
Other	36,320	50,170
Total current liabilities	205,805	197,914
Deferred credits and other liabilities
Operating lease liabilities	6,320	7,044
Finance lease liabilities	0	0
Deferred income taxes	68,328	67,311
Regulatory liabilities	113,821	111,554
Unamortized tax credits	11,232	11,532
Defined benefit pension and other postretirement benefit plans liability	0	0
Other	26,598	27,332
Total deferred credits and other liabilities	226,299	224,773
Total liabilities and shareholders’ equity	1,057,224	1,048,453
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	93,000	70,500
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	0	0
Plant and equipment	0	0
Financing lease right-of-use assets	0	0
Less accumulated depreciation	0	0
Construction in progress	0	0
Utility property, plant and equipment, net	0	0
Nonutility property, plant and equipment, less accumulated depreciation	0	0
Total property, plant and equipment, net	0	0
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	77	77	77
Restricted cash	0	0
Advances to affiliates	0	0
Customer accounts receivable, net	0	0
Accrued unbilled revenues, net	0	0
Other accounts receivable, net	0	0
Fuel oil stock, at average cost	0	0
Materials and supplies, at average cost	0	0
Prepayments and other	0	0
Regulatory assets	0	0
Total current assets	77	77
Other long-term assets
Operating lease right-of-use assets	0	0
Regulatory assets	0	0
Other	0	0
Total other long-term assets	0	0
Total assets	77	77
Capitalization
Common stock equity	77	77	$ 77	$ 77
Preferred stock of subsidiaries - not subject to mandatory redemption	0	0
Long-term debt, net	0	0
Total capitalization	77	77
Current liabilities
Current portion of operating lease liabilities	0	0
Current portion of long-term debt	0
Accounts payable	0	0
Interest and dividends payable	0	0
Taxes accrued, including revenue taxes	0	0
Regulatory liabilities	0	0
Other	0	0
Total current liabilities	0	0
Deferred credits and other liabilities
Operating lease liabilities	0	0
Finance lease liabilities	0	0
Deferred income taxes	0	0
Regulatory liabilities	0	0
Unamortized tax credits	0	0
Defined benefit pension and other postretirement benefit plans liability	0	0
Other	0
Total deferred credits and other liabilities	0	0
Total liabilities and shareholders’ equity	77	77
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	$ 0	$ 0