Electric utility segment - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Utility property, plant and equipment
Total property, plant and equipment, net	$ 6,296,088			$ 6,150,126
Current assets
Cash and cash equivalents	1,159,635			679,546	$ 667,129
Restricted cash	13,645			15,028	15,164
Other long-term assets
Operating lease right-of-use assets	84,645			94,905
Total assets	17,731,228			17,243,821
Capitalization
Common stock equity	1,577,041	$ 1,085,273	$ 2,377,380	2,344,841	2,224,354	$ 2,249,377	$ 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	50,076			51,206
Deferred credits and other liabilities
Deferred income taxes	0			297,954
Total liabilities and shareholders’ equity	17,731,228			17,243,821
Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	52,019			52,098
Plant and equipment	8,413,151			8,232,810
Financing lease right-of-use assets	449,572			342,174
Less accumulated depreciation	(3,323,190)			(3,197,514)
Construction in progress	346,673			320,223
Utility property, plant and equipment, net	5,938,225			5,749,791
Nonutility property, plant and equipment, less accumulated depreciation	6,939			6,942
Total property, plant and equipment, net	5,945,164			5,756,733
Investment in wholly owned subsidiaries, at equity	0			0
Current assets
Cash and cash equivalents	147,624			106,077	274,854
Restricted cash	2,000			2,000	2,000
Advances to affiliates	0			0
Customer accounts receivable, net	207,953			244,309
Accrued unbilled revenues, net	199,657			185,644
Other accounts receivable, net	85,488			111,519
Fuel oil stock, at average cost	109,043			148,237
Materials and supplies, at average cost	114,054			114,433
Prepayments and other	94,823			58,491
Regulatory assets	59,836			68,453
Total current assets	1,020,478			1,039,163
Other long-term assets
Operating lease right-of-use assets	61,007			71,877
Regulatory assets	254,411			226,351
Other	282,144			189,430
Total other long-term assets	597,562			487,658
Total assets	7,563,204			7,283,554
Capitalization
Common stock equity	1,110,259	$ 1,192,842	$ 2,435,282	2,409,110	2,383,023	$ 2,371,889	$ 2,358,884	2,344,170
Preferred stock of subsidiaries - not subject to mandatory redemption	34,293			34,293
Long-term debt, net	1,888,003			1,934,277
Total capitalization	3,032,555			4,377,680
Current liabilities
Current portion of operating lease liabilities	15,411			16,617
Current portion of long-term debt	46,977			0
Accounts payable	202,427			191,040
Interest and dividends payable	29,817			22,882
Taxes accrued, including revenue taxes	261,653			291,942
Regulatory liabilities	25,684			36,559
Wildfire tort-related claims (Note 2)	478,750			75,000
Other	113,695			96,436
Total current liabilities	1,174,414			730,476
Deferred credits and other liabilities
Operating lease liabilities	51,096			62,098
Finance lease liabilities	430,923			330,978
Deferred income taxes	0			399,001
Regulatory liabilities	1,165,415			1,114,131
Unamortized tax credits	78,206			84,312
Defined benefit pension and other postretirement benefit plans liability	60,881			60,671
Wildfire tort-related claims (Note 2)	1,436,250			0
Other	133,464			124,207
Total deferred credits and other liabilities	3,356,235			2,175,398
Total liabilities and shareholders’ equity	7,563,204			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	(669,450)			(722,211)
Current assets
Cash and cash equivalents	0			0	0
Restricted cash	0			0	0
Advances to affiliates	(46,200)			(70,500)
Customer accounts receivable, net	0			0
Accrued unbilled revenues, net	0			0
Other accounts receivable, net	(223,945)			(77,480)
Fuel oil stock, at average cost	0			0
Materials and supplies, at average cost	0			0
Prepayments and other	(1,718)			(1,638)
Regulatory assets	0			0
Total current assets	(271,863)			(149,618)
Other long-term assets
Operating lease right-of-use assets	0			0
Regulatory assets	0			0
Other	(40,584)			(14,171)
Total other long-term assets	(40,584)			(14,171)
Total assets	(981,897)			(886,000)
Capitalization
Common stock equity	(669,450)			(722,211)	(703,311)			(701,833)
Preferred stock of subsidiaries - not subject to mandatory redemption	0			0
Long-term debt, net	0			0
Total capitalization	(669,450)			(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	(537)			(375)
Taxes accrued, including revenue taxes	(1,718)			(1,638)
Regulatory liabilities	0			0
Wildfire tort-related claims (Note 2)	0			0
Other	(223,408)			(77,105)
Total current liabilities	(271,863)			(149,618)
Deferred credits and other liabilities
Operating lease liabilities	0			0
Finance lease liabilities	0			0
Deferred income taxes	(25,558)			0
Regulatory liabilities	0			0
Unamortized tax credits	0			0
Defined benefit pension and other postretirement benefit plans liability	(15,026)			(14,171)
Wildfire tort-related claims (Note 2)	0
Other	0			0
Total deferred credits and other liabilities	(40,584)			(14,171)
Total liabilities and shareholders’ equity	(981,897)			(886,000)
Consolidating adjustments | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	(46,200)			(70,500)
Hawaiian Electric
Current assets
Cash and cash equivalents	677,700
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	42,860			42,859
Plant and equipment	5,503,512			5,398,281
Financing lease right-of-use assets	362,741			306,099
Less accumulated depreciation	(2,028,302)			(1,925,660)
Construction in progress	276,525			247,836
Utility property, plant and equipment, net	4,157,336			4,069,415
Nonutility property, plant and equipment, less accumulated depreciation	5,292			5,295
Total property, plant and equipment, net	4,162,628			4,074,710
Investment in wholly owned subsidiaries, at equity	669,450			722,211
Current assets
Cash and cash equivalents	99,392			89,755	233,518
Restricted cash	2,000			2,000	2,000
Advances to affiliates	46,200			70,500
Customer accounts receivable, net	32,405			172,747
Accrued unbilled revenues, net	23,595			136,367
Other accounts receivable, net	193,771			143,160
Fuel oil stock, at average cost	79,736			108,228
Materials and supplies, at average cost	66,289			64,334
Prepayments and other	70,526			40,767
Regulatory assets	46,579			58,920
Total current assets	660,493			886,778
Other long-term assets
Operating lease right-of-use assets	31,134			34,856
Regulatory assets	207,572			189,417
Other	250,162			134,033
Total other long-term assets	488,868			358,306
Total assets	5,981,439			6,042,005
Capitalization
Common stock equity	1,110,259			2,409,110	2,383,023			2,344,170
Preferred stock of subsidiaries - not subject to mandatory redemption	22,293			22,293
Long-term debt, net	1,387,029			1,426,516
Total capitalization	2,519,581			3,857,919
Current liabilities
Current portion of operating lease liabilities	5,183			6,788
Current portion of long-term debt	39,980
Accounts payable	141,147			136,102
Interest and dividends payable	22,194			17,085
Taxes accrued, including revenue taxes	187,756			211,840
Regulatory liabilities	10,887			20,013
Wildfire tort-related claims (Note 2)	383,000			75,000
Other	91,572			90,131
Total current liabilities	881,719			556,959
Deferred credits and other liabilities
Operating lease liabilities	30,785			34,262
Finance lease liabilities	346,344			295,935
Deferred income taxes	0			280,029
Regulatory liabilities	839,392			803,404
Unamortized tax credits	56,219			61,130
Defined benefit pension and other postretirement benefit plans liability	75,907			74,842
Wildfire tort-related claims (Note 2)	1,149,000
Other	82,492			77,525
Total deferred credits and other liabilities	2,580,139			1,627,127
Total liabilities and shareholders’ equity	5,981,439			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	1,494,982			1,459,639
Financing lease right-of-use assets	36,074			36,075
Less accumulated depreciation	(685,469)			(666,581)
Construction in progress	27,878			33,488
Utility property, plant and equipment, net	879,110			868,266
Nonutility property, plant and equipment, less accumulated depreciation	115			115
Total property, plant and equipment, net	879,225			868,381
Investment in wholly owned subsidiaries, at equity	0			0
Current assets
Cash and cash equivalents	25,734			10,658	32,716
Restricted cash	0			0	0
Advances to affiliates	0			0
Customer accounts receivable, net	7,594			38,216
Accrued unbilled revenues, net	5,568			25,102
Other accounts receivable, net	61,265			13,318
Fuel oil stock, at average cost	10,657			17,968
Materials and supplies, at average cost	14,736			14,397
Prepayments and other	7,456			7,724
Regulatory assets	4,761			5,771
Total current assets	137,771			133,154
Other long-term assets
Operating lease right-of-use assets	22,422			27,470
Regulatory assets	16,091			13,575
Other	37,716			36,439
Total other long-term assets	76,229			77,484
Total assets	1,093,225			1,079,019
Capitalization
Common stock equity	237,105			359,790	352,170			344,720
Preferred stock of subsidiaries - not subject to mandatory redemption	7,000			7,000
Long-term debt, net	244,437			249,339
Total capitalization	488,542			616,129
Current liabilities
Current portion of operating lease liabilities	7,302			7,025
Current portion of long-term debt	4,998
Accounts payable	24,484			29,418
Interest and dividends payable	3,652			3,098
Taxes accrued, including revenue taxes	40,137			43,932
Regulatory liabilities	9,782			8,508
Wildfire tort-related claims (Note 2)	47,875			0
Other	28,782			33,240
Total current liabilities	167,012			125,221
Deferred credits and other liabilities
Operating lease liabilities	15,480			20,792
Finance lease liabilities	34,543			35,043
Deferred income taxes	3,024			51,661
Regulatory liabilities	208,022			199,173
Unamortized tax credits	10,887			11,650
Defined benefit pension and other postretirement benefit plans liability	0			0
Wildfire tort-related claims (Note 2)	143,625
Other	22,090			19,350
Total deferred credits and other liabilities	437,671			337,669
Total liabilities and shareholders’ equity	1,093,225			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	1,414,657			1,374,890
Financing lease right-of-use assets	50,757			0
Less accumulated depreciation	(609,419)			(605,273)
Construction in progress	42,270			38,899
Utility property, plant and equipment, net	901,779			812,110
Nonutility property, plant and equipment, less accumulated depreciation	1,532			1,532
Total property, plant and equipment, net	903,311			813,642
Investment in wholly owned subsidiaries, at equity	0			0
Current assets
Cash and cash equivalents	11,833			5,587	8,543
Restricted cash	0			0	0
Advances to affiliates	0			0
Customer accounts receivable, net	9,774			33,346
Accrued unbilled revenues, net	3,560			24,175
Other accounts receivable, net	54,397			32,521
Fuel oil stock, at average cost	18,650			22,041
Materials and supplies, at average cost	33,029			35,702
Prepayments and other	18,559			11,638
Regulatory assets	8,496			3,762
Total current assets	158,298			168,772
Other long-term assets
Operating lease right-of-use assets	7,451			9,551
Regulatory assets	30,748			23,359
Other	34,850			33,129
Total other long-term assets	73,049			66,039
Total assets	1,134,658			1,048,453
Capitalization
Common stock equity	280,629			362,344	351,064			357,036
Preferred stock of subsidiaries - not subject to mandatory redemption	5,000			5,000
Long-term debt, net	256,537			258,422
Total capitalization	542,166			625,766
Current liabilities
Current portion of operating lease liabilities	2,926			2,804
Current portion of long-term debt	1,999
Accounts payable	36,796			25,520
Interest and dividends payable	4,508			3,074
Taxes accrued, including revenue taxes	34,984			37,808
Regulatory liabilities	5,015			8,038
Wildfire tort-related claims (Note 2)	47,875			0
Other	33,180			50,170
Total current liabilities	213,483			197,914
Deferred credits and other liabilities
Operating lease liabilities	4,831			7,044
Finance lease liabilities	50,036			0
Deferred income taxes	22,534			67,311
Regulatory liabilities	118,001			111,554
Unamortized tax credits	11,100			11,532
Defined benefit pension and other postretirement benefit plans liability	0			0
Wildfire tort-related claims (Note 2)	143,625
Other	28,882			27,332
Total deferred credits and other liabilities	379,009			224,773
Total liabilities and shareholders’ equity	1,134,658			1,048,453
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	46,200			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	10,665			77	77
Restricted cash	0			0	0
Advances to affiliates	0			0
Customer accounts receivable, net	158,180			0
Accrued unbilled revenues, net	166,934			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	335,779			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	335,779			77
Capitalization
Common stock equity	151,716			77	$ 77			$ 77
Preferred stock of subsidiaries - not subject to mandatory redemption	0			0
Long-term debt, net	0			0
Total capitalization	151,716			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	494			0
Regulatory liabilities	0			0
Wildfire tort-related claims (Note 2)	0			0
Other	183,569			0
Total current liabilities	184,063			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
Wildfire tort-related claims (Note 2)	0
Other	0
Total deferred credits and other liabilities	0			0
Total liabilities and shareholders’ equity	335,779			77
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated | Affiliated Entity
Current liabilities
Short-term borrowings from non-affiliates	$ 0			$ 0