Electric utility segment - Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Utility property, plant and equipment
Finance lease right-of-use assets	$ 342,834	$ 49,370
Total property, plant and equipment, net	6,150,126	5,687,003
Current assets
Cash and cash equivalents	679,546	199,877	$ 305,551
Restricted cash	15,000	5,100
Other long-term assets
Operating lease right-of-use-assets	94,905	115,684
Total assets	17,243,821	16,284,244	15,822,637
Capitalization
Total shareholders’ equity	2,344,841	2,202,499	2,390,884	$ 2,337,502
Cumulative preferred stock – not subject to mandatory redemption	34,293	34,293
Current liabilities
Short-term borrowings—other than bank	0	172,568
Interest and dividends payable	51,206	21,333
Deferred credits and other liabilities
Deferred income taxes	297,954	262,462
Total capitalization and liabilities	17,243,821	16,284,244
Hawaiian Electric Company, Inc. and Subsidiaries
Utility property, plant and equipment
Land	52,098	52,060
Plant and equipment	8,232,810	7,979,510
Finance lease right-of-use assets	342,174	48,371
Less accumulated depreciation	(3,197,514)	(3,086,499)
Construction in progress	320,223	275,353
Utility property, plant and equipment, net	5,749,791	5,268,795
Nonutility property, plant and equipment, less accumulated depreciation	6,942	6,945
Total property, plant and equipment, net	5,756,733	5,275,740
Investment in wholly-owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	106,077	39,242	52,169
Restricted cash	2,000	0
Advances to affiliates	0	0
Customer accounts receivable, net	244,309	288,338
Accrued unbilled revenues, net	185,644	183,280
Other accounts receivable, net	111,519	13,567
Fuel oil stock, at average cost	148,237	191,530
Materials and supplies, at average cost	114,433	79,568
Prepayments and other	58,491	33,482
Regulatory assets	68,453	52,273
Total current assets	1,039,163	881,280
Other long-term assets
Operating lease right-of-use-assets	71,877	89,318
Regulatory assets	226,351	190,240
Other	189,430	160,889
Total other long-term assets	487,658	440,447
Total assets	7,283,554	6,597,467
Capitalization
Total shareholders’ equity	2,409,110	2,344,170	2,261,899	2,141,918
Cumulative preferred stock – not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,934,277	1,584,854
Total capitalization	4,377,680	3,963,317
Current liabilities
Current portion of operating lease liabilities	16,617	19,095
Current portion of long-term debt, net	0	99,962
Accounts payable	191,040	202,492
Interest and dividends payable	22,882	17,176
Taxes accrued, including revenue taxes	291,942	289,902
Regulatory liabilities	36,559	31,475
Other	171,436	85,596
Total current liabilities	730,476	833,665
Deferred credits and other liabilities
Operating lease liabilities	62,098	78,715
Finance lease liabilities	330,978	46,048
Deferred income taxes	399,001	384,430
Regulatory liabilities	1,114,131	1,024,175
Unamortized tax credits	84,312	95,300
Defined benefit pension and other postretirement benefit plans liability	60,671	49,748
Other	124,207	122,069
Total deferred credits and other liabilities	2,175,398	1,800,485
Total capitalization and liabilities	7,283,554	6,597,467
Hawaiian Electric Company, Inc. and Subsidiaries | Nonrelated Party
Current liabilities
Short-term borrowings—other than bank	0	87,967
Hawaiian Electric Company, Inc. and Subsidiaries | Affiliated Entity
Current liabilities
Short-term borrowings—other than bank	0	0
Consolidating adjustments | Hawaiian Electric Company, Inc. and Subsidiaries
Utility property, plant and equipment
Land	0	0
Plant and equipment	0	0
Finance 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	(722,211)	(701,833)
Current assets
Cash and cash equivalents	0	0	0
Restricted cash	0
Advances to affiliates	(70,500)	(26,200)
Customer accounts receivable, net	0	0
Accrued unbilled revenues, net	0	0
Other accounts receivable, net	(77,480)	(22,384)
Fuel oil stock, at average cost	0	0
Materials and supplies, at average cost	0	0
Prepayments and other	(1,638)	(1,041)
Regulatory assets	0	0
Total current assets	(149,618)	(49,625)
Other long-term assets
Operating lease right-of-use-assets	0	0
Regulatory assets	0	0
Other	(14,171)	(16,288)
Total other long-term assets	(14,171)	(16,288)
Total assets	(886,000)	(767,746)
Capitalization
Total shareholders’ equity	(722,211)	(701,833)	(676,237)	(626,891)
Cumulative preferred stock – not subject to mandatory redemption	0	0
Long-term debt, net	0	0
Total capitalization	(722,211)	(701,833)
Current liabilities
Current portion of operating lease liabilities	0	0
Current portion of long-term debt, net		0
Accounts payable	0	0
Interest and dividends payable	(375)	(80)
Taxes accrued, including revenue taxes	(1,638)	(1,041)
Regulatory liabilities	0	0
Other	(77,105)	(22,304)
Total current liabilities	(149,618)	(49,625)
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	(14,171)	(16,288)
Other	0	0
Total deferred credits and other liabilities	(14,171)	(16,288)
Total capitalization and liabilities	(886,000)	(767,746)
Consolidating adjustments | Hawaiian Electric Company, Inc. and Subsidiaries | Nonrelated Party
Current liabilities
Short-term borrowings—other than bank		0
Consolidating adjustments | Hawaiian Electric Company, Inc. and Subsidiaries | Affiliated Entity
Current liabilities
Short-term borrowings—other than bank	(70,500)	(26,200)
Hawaiian Electric
Utility property, plant and equipment
Total property, plant and equipment, net	1,495	1,877
Current assets
Cash and cash equivalents	136,510	611	479
Other long-term assets
Total assets	3,216,333	2,929,232
Capitalization
Total shareholders’ equity	2,344,841	2,202,499
Current liabilities
Short-term borrowings—other than bank	0	34,918
Deferred credits and other liabilities
Total capitalization and liabilities	3,216,333	2,929,232
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Utility property, plant and equipment
Land	42,859	42,860
Plant and equipment	5,398,281	5,260,685
Finance lease right-of-use assets	306,099	48,371
Less accumulated depreciation	(1,925,660)	(1,855,150)
Construction in progress	247,836	215,560
Utility property, plant and equipment, net	4,069,415	3,712,326
Nonutility property, plant and equipment, less accumulated depreciation	5,295	5,298
Total property, plant and equipment, net	4,074,710	3,717,624
Investment in wholly-owned subsidiaries, at equity	722,211	701,833
Current assets
Cash and cash equivalents	89,755	27,579	23,344
Restricted cash	2,000
Advances to affiliates	70,500	0
Customer accounts receivable, net	172,747	216,802
Accrued unbilled revenues, net	136,367	136,508
Other accounts receivable, net	143,160	23,746
Fuel oil stock, at average cost	108,228	153,342
Materials and supplies, at average cost	64,334	48,130
Prepayments and other	40,767	24,040
Regulatory assets	58,920	46,504
Total current assets	886,778	676,651
Other long-term assets
Operating lease right-of-use-assets	34,856	42,752
Regulatory assets	189,417	154,040
Other	134,033	115,028
Total other long-term assets	358,306	311,820
Total assets	6,042,005	5,407,928
Capitalization
Total shareholders’ equity	2,409,110	2,344,170	2,261,899	2,141,918
Cumulative preferred stock – not subject to mandatory redemption	22,293	22,293
Long-term debt, net	1,426,516	1,126,915
Total capitalization	3,857,919	3,493,378
Current liabilities
Current portion of operating lease liabilities	6,788	9,775
Current portion of long-term debt, net		49,981
Accounts payable	136,102	143,253
Interest and dividends payable	17,085	12,398
Taxes accrued, including revenue taxes	211,840	207,798
Regulatory liabilities	20,013	13,145
Other	165,131	64,659
Total current liabilities	556,959	615,176
Deferred credits and other liabilities
Operating lease liabilities	34,262	41,049
Finance lease liabilities	295,935	46,048
Deferred income taxes	280,029	271,234
Regulatory liabilities	803,404	729,683
Unamortized tax credits	61,130	69,614
Defined benefit pension and other postretirement benefit plans liability	74,842	65,907
Other	77,525	75,839
Total deferred credits and other liabilities	1,627,127	1,299,374
Total capitalization and liabilities	6,042,005	5,407,928
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Nonrelated Party
Current liabilities
Short-term borrowings—other than bank		87,967
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Affiliated Entity
Current liabilities
Short-term borrowings—other than bank	0	26,200
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Utility property, plant and equipment
Land	5,645	5,606
Plant and equipment	1,459,639	1,425,442
Finance lease right-of-use assets	36,075	0
Less accumulated depreciation	(666,581)	(644,457)
Construction in progress	33,488	23,989
Utility property, plant and equipment, net	868,266	810,580
Nonutility property, plant and equipment, less accumulated depreciation	115	115
Total property, plant and equipment, net	868,381	810,695
Investment in wholly-owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	10,658	5,092	5,326
Restricted cash	0
Advances to affiliates	0	4,500
Customer accounts receivable, net	38,216	39,339
Accrued unbilled revenues, net	25,102	23,839
Other accounts receivable, net	13,318	5,519
Fuel oil stock, at average cost	17,968	16,964
Materials and supplies, at average cost	14,397	9,783
Prepayments and other	7,724	6,346
Regulatory assets	5,771	2,435
Total current assets	133,154	113,817
Other long-term assets
Operating lease right-of-use-assets	27,470	34,283
Regulatory assets	13,575	21,816
Other	36,439	32,654
Total other long-term assets	77,484	88,753
Total assets	1,079,019	1,013,265
Capitalization
Total shareholders’ equity	359,790	344,720	332,900	317,451
Cumulative preferred stock – not subject to mandatory redemption	7,000	7,000
Long-term debt, net	249,339	224,439
Total capitalization	616,129	576,159
Current liabilities
Current portion of operating lease liabilities	7,025	6,690
Current portion of long-term debt, net		19,992
Accounts payable	29,418	32,113
Interest and dividends payable	3,098	2,576
Taxes accrued, including revenue taxes	43,932	42,436
Regulatory liabilities	8,508	8,553
Other	33,240	20,856
Total current liabilities	125,221	133,216
Deferred credits and other liabilities
Operating lease liabilities	20,792	27,817
Finance lease liabilities	35,043	0
Deferred income taxes	51,661	50,615
Regulatory liabilities	199,173	194,222
Unamortized tax credits	11,650	13,150
Defined benefit pension and other postretirement benefit plans liability	0	129
Other	19,350	17,957
Total deferred credits and other liabilities	337,669	303,890
Total capitalization and liabilities	1,079,019	1,013,265
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Nonrelated Party
Current liabilities
Short-term borrowings—other than bank		0
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Affiliated Entity
Current liabilities
Short-term borrowings—other than bank	0	0
Maui Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Utility property, plant and equipment
Land	3,594	3,594
Plant and equipment	1,374,890	1,293,383
Finance lease right-of-use assets	0	0
Less accumulated depreciation	(605,273)	(586,892)
Construction in progress	38,899	35,804
Utility property, plant and equipment, net	812,110	745,889
Nonutility property, plant and equipment, less accumulated depreciation	1,532	1,532
Total property, plant and equipment, net	813,642	747,421
Investment in wholly-owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	5,587	6,494	23,422
Restricted cash	0
Advances to affiliates	0	21,700
Customer accounts receivable, net	33,346	32,197
Accrued unbilled revenues, net	24,175	22,933
Other accounts receivable, net	32,521	6,686
Fuel oil stock, at average cost	22,041	21,224
Materials and supplies, at average cost	35,702	21,655
Prepayments and other	11,638	4,137
Regulatory assets	3,762	3,334
Total current assets	168,772	140,360
Other long-term assets
Operating lease right-of-use-assets	9,551	12,283
Regulatory assets	23,359	14,384
Other	33,129	29,495
Total other long-term assets	66,039	56,162
Total assets	1,048,453	943,943
Capitalization
Total shareholders’ equity	362,344	357,036	343,260	309,363
Cumulative preferred stock – not subject to mandatory redemption	5,000	5,000
Long-term debt, net	258,422	233,500
Total capitalization	625,766	595,536
Current liabilities
Current portion of operating lease liabilities	2,804	2,630
Current portion of long-term debt, net		29,989
Accounts payable	25,520	27,126
Interest and dividends payable	3,074	2,282
Taxes accrued, including revenue taxes	37,808	40,709
Regulatory liabilities	8,038	9,777
Other	50,170	22,385
Total current liabilities	197,914	134,898
Deferred credits and other liabilities
Operating lease liabilities	7,044	9,849
Finance lease liabilities	0	0
Deferred income taxes	67,311	62,581
Regulatory liabilities	111,554	100,270
Unamortized tax credits	11,532	12,536
Defined benefit pension and other postretirement benefit plans liability	0	0
Other	27,332	28,273
Total deferred credits and other liabilities	224,773	213,509
Total capitalization and liabilities	1,048,453	943,943
Maui Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Nonrelated Party
Current liabilities
Short-term borrowings—other than bank		0
Maui Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Affiliated Entity
Current liabilities
Short-term borrowings—other than bank	70,500	0
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Utility property, plant and equipment
Land	0	0
Plant and equipment	0	0
Finance 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
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
Total shareholders’ equity	77	77	$ 77	$ 77
Cumulative preferred stock – 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, net		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
Total deferred credits and other liabilities	0	0
Total capitalization and liabilities	77	77
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Nonrelated Party
Current liabilities
Short-term borrowings—other than bank		0
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries | Affiliated Entity
Current liabilities
Short-term borrowings—other than bank	$ 0	$ 0