Electric utility segment - Consolidating Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Income Statements, Captions [Line Items]
Revenues	$ 799,180	$ 833,239	$ 795,417	$ 792,014	$ 853,424	$ 800,899	$ 798,800	$ 834,380	$ 3,219,850	$ 3,287,503	$ 3,420,917
Expenses
Total expenses									4,926,610	3,012,511	3,141,362
Operating income (loss)	53,662	(149,720)	(1,661,589)	50,887	74,331	62,552	68,111	69,998	(1,706,760)	274,992	279,555
Allowance for equity funds used during construction									13,786	15,164	10,574
Retirement defined benefits credit—other than service costs									3,754	4,014	3,688
Allowance for borrowed funds used during construction									5,470	5,201	3,416
Interest income									19,362	9,105	0
Income (loss) from continuing operations before income taxes									(1,791,595)	182,300	201,954
Income tax expense (benefit)									(470,962)	34,534	38,915
Income (loss) from continuing operations									(1,424,119)	201,128	243,028
Preferred stock dividends of Hawaiian Electric									1,890	1,890	1,890
Net income (loss) for common stock	$ (68,245)	$ (104,402)	$ (1,295,484)	$ 42,122	$ 48,789	$ 41,118	$ 54,610	$ 54,721	(1,426,009)	199,238	241,138
Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues									3,206,700	3,269,521	3,408,587
Expenses
Fuel oil									1,078,045	1,211,420	1,265,614
Purchased power									703,371	671,769	793,584
Other operation and maintenance									609,672	533,557	497,601
Wildfire tort-related claims, net (Note 2)									1,875,000	0	0
Depreciation									251,142	243,705	235,424
Taxes, other than income taxes									301,328	306,912	317,173
Total expenses									4,818,558	2,967,363	3,109,396
Operating income (loss)									(1,611,858)	302,158	299,191
Allowance for equity funds used during construction									13,786	15,164	10,574
Equity in earnings of subsidiaries									0	0	0
Retirement defined benefits credit—other than service costs									4,137	4,303	3,835
Interest expense and other charges, net									(82,082)	(86,140)	(76,416)
Allowance for borrowed funds used during construction									5,470	5,201	3,416
Interest income									6,633	6,454	0
Income (loss) from continuing operations before income taxes									(1,663,914)	247,140	240,600
Income tax expense (benefit)									(439,547)	51,193	49,676
Loss from continuing operations									(1,224,367)	195,947	190,924
Preferred stock dividends of subsidiaries									915	915	915
Income (loss) from continuing operations									(1,225,282)	195,032	190,009
Preferred stock dividends of Hawaiian Electric									1,080	1,080	1,080
Net income (loss) for common stock									(1,226,362)	193,952	188,929
Consolidating adjustments | Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues									(6,165)	0	(327)
Expenses
Fuel oil									0	0	0
Purchased power									0	0	0
Other operation and maintenance									(6,165)	0	0
Wildfire tort-related claims, net (Note 2)									0
Depreciation									0	0	0
Taxes, other than income taxes									0	0	0
Total expenses									(6,165)	0	0
Operating income (loss)									0	0	(327)
Allowance for equity funds used during construction									0	0	0
Equity in earnings of subsidiaries									248,004	(44,809)	(47,493)
Retirement defined benefits credit—other than service costs									0	0	0
Interest expense and other charges, net									5,934	805	327
Allowance for borrowed funds used during construction									0	0	0
Interest income									(5,934)	(805)
Income (loss) from continuing operations before income taxes									248,004	(44,809)	(47,493)
Income tax expense (benefit)									0	0	0
Loss from continuing operations									248,004	(44,809)	(47,493)
Preferred stock dividends of subsidiaries									0	0	0
Income (loss) from continuing operations									248,004	(44,809)	(47,493)
Preferred stock dividends of Hawaiian Electric									0	0	0
Net income (loss) for common stock									248,004	(44,809)	(47,493)
Hawaiian Electric
Condensed Income Statements, Captions [Line Items]
Revenues									492	268	320
Expenses
Total expenses									40,382	24,228	21,981
Operating income (loss)									(1,311,072)	162,210	171,426
Retirement defined benefits credit—other than service costs									(383)	(289)	(147)
Interest income									12,729	2,651	0
Income (loss) from continuing operations before income taxes									(1,338,132)	131,942	149,282
Income tax expense (benefit)									(15,609)	(13,934)	(11,867)
Net income (loss) for common stock									(1,426,009)	199,238	241,138
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues									2,283,148	2,356,478	2,452,969
Expenses
Fuel oil									790,004	913,801	917,801
Purchased power									517,583	486,067	601,235
Other operation and maintenance									390,111	343,462	326,785
Wildfire tort-related claims, net (Note 2)									1,500,000
Depreciation									167,909	164,150	158,725
Taxes, other than income taxes									215,137	221,664	228,843
Total expenses									3,580,744	2,129,144	2,233,389
Operating income (loss)									(1,297,596)	227,334	219,580
Allowance for equity funds used during construction									10,853	11,721	8,464
Equity in earnings of subsidiaries									(248,004)	44,809	47,493
Retirement defined benefits credit—other than service costs									3,574	3,735	3,296
Interest expense and other charges, net									(59,906)	(62,362)	(55,260)
Allowance for borrowed funds used during construction									4,300	4,081	2,769
Interest income									11,136	5,113
Income (loss) from continuing operations before income taxes									(1,575,643)	234,431	226,342
Income tax expense (benefit)									(350,361)	39,399	36,333
Loss from continuing operations									(1,225,282)	195,032	190,009
Preferred stock dividends of subsidiaries									0	0	0
Income (loss) from continuing operations									(1,225,282)	195,032	190,009
Preferred stock dividends of Hawaiian Electric									1,080	1,080	1,080
Net income (loss) for common stock									(1,226,362)	193,952	188,929
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues									483,715	464,161	485,590
Expenses
Fuel oil									121,719	105,009	133,238
Purchased power									132,086	142,837	143,636
Other operation and maintenance									102,883	85,261	85,110
Wildfire tort-related claims, net (Note 2)									187,500
Depreciation									43,855	42,541	41,404
Taxes, other than income taxes									45,025	43,095	44,685
Total expenses									633,068	418,743	448,073
Operating income (loss)									(149,353)	45,418	37,517
Allowance for equity funds used during construction									1,189	1,411	898
Equity in earnings of subsidiaries									0	0	0
Retirement defined benefits credit—other than service costs									665	667	666
Interest expense and other charges, net									(11,422)	(11,650)	(10,659)
Allowance for borrowed funds used during construction									355	451	277
Interest income									1,062	1,071
Income (loss) from continuing operations before income taxes									(157,504)	37,368	28,699
Income tax expense (benefit)									(41,624)	8,327	6,349
Loss from continuing operations									(115,880)	29,041	22,350
Preferred stock dividends of subsidiaries									534	534	534
Income (loss) from continuing operations									(116,414)	28,507	21,816
Preferred stock dividends of Hawaiian Electric									0	0	0
Net income (loss) for common stock									(116,414)	28,507	21,816
Maui Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues									440,432	448,882	470,355
Expenses
Fuel oil									166,322	192,610	214,575
Purchased power									53,702	42,865	48,713
Other operation and maintenance									121,693	104,834	85,706
Wildfire tort-related claims, net (Note 2)									187,500
Depreciation									39,378	37,014	35,295
Taxes, other than income taxes									41,166	42,153	43,645
Total expenses									609,761	419,476	427,934
Operating income (loss)									(169,329)	29,406	42,421
Allowance for equity funds used during construction									1,744	2,032	1,212
Equity in earnings of subsidiaries									0	0	0
Retirement defined benefits credit—other than service costs									(102)	(99)	(127)
Interest expense and other charges, net									(16,688)	(12,933)	(10,824)
Allowance for borrowed funds used during construction									815	669	370
Interest income									369	1,075
Income (loss) from continuing operations before income taxes									(183,191)	20,150	33,052
Income tax expense (benefit)									(48,700)	3,467	6,994
Loss from continuing operations									(134,491)	16,683	26,058
Preferred stock dividends of subsidiaries									381	381	381
Income (loss) from continuing operations									(134,872)	16,302	25,677
Preferred stock dividends of Hawaiian Electric									0	0	0
Net income (loss) for common stock									(134,872)	16,302	25,677
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues									5,570
Expenses
Fuel oil									0
Purchased power									0
Other operation and maintenance									1,150
Wildfire tort-related claims, net (Note 2)									0
Depreciation									0
Taxes, other than income taxes									0
Total expenses									1,150
Operating income (loss)									4,420
Allowance for equity funds used during construction									0	0	0
Equity in earnings of subsidiaries									0
Retirement defined benefits credit—other than service costs									0
Interest expense and other charges, net									0
Allowance for borrowed funds used during construction									0
Interest income									0
Income (loss) from continuing operations before income taxes									4,420
Income tax expense (benefit)									1,138
Loss from continuing operations									3,282	$ 0	$ 0
Preferred stock dividends of subsidiaries									0
Income (loss) from continuing operations									3,282
Preferred stock dividends of Hawaiian Electric									0
Net income (loss) for common stock									$ 3,282