Electric utility segment - Condensed Consolidating Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Condensed Income Statements, Captions [Line Items]
Revenues	$ 790,610	$ 833,239	$ 2,281,072	$ 2,420,670
Expenses
Total expenses	738,564	982,959	2,112,859	4,181,092
Operating income (loss)	52,046	(149,720)	168,213	(1,760,422)
Allowance for equity funds used during construction	3,821	3,300	11,108	10,276
Retirement defined benefits credit (expense)—other than service costs	817	849	2,653	2,851
Allowance for borrowed funds used during construction	1,500	1,331	4,379	4,061
Interest income	6,960	3,662	27,162	9,929
Income (loss) before income taxes	39,946	(172,663)	113,460	(1,829,381)
Income tax expense (benefit)	8,728	(49,954)	28,540	(479,109)
Net income (loss) attributable to Hawaiian Electric			84,920	(1,356,347)
Preferred stock dividends of Hawaiian Electric	471	471	1,417	1,417
Net income (loss) for common stock	30,747	(104,402)	83,503	(1,357,764)
Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	787,428	829,617	2,268,276	2,410,526
Expenses
Fuel oil	240,547	279,038	689,855	821,986
Purchased power	183,813	189,165	505,493	530,310
Other operation and maintenance	161,819	162,197	463,144	453,648
Wildfire tort-related claims	0	163,000	0	1,875,000
Depreciation	64,022	62,812	192,015	188,436
Taxes, other than income taxes	74,434	77,969	214,495	226,795
Total expenses	724,635	934,181	2,065,002	4,096,175
Operating income (loss)	62,793	(104,564)	203,274	(1,685,649)
Allowance for equity funds used during construction	3,821	3,300	11,108	10,276
Equity in earnings of subsidiaries	0	0	0	0
Retirement defined benefits credit (expense)—other than service costs	998	959	3,101	3,103
Interest expense and other charges, net	(22,114)	(20,223)	(66,272)	(61,625)
Allowance for borrowed funds used during construction	1,500	1,331	4,379	4,061
Interest income	1,461	1,671	4,657	4,555
Income (loss) before income taxes	48,459	(117,526)	160,247	(1,725,279)
Income tax expense (benefit)	10,973	(35,439)	34,797	(454,017)
Net income (loss)	37,486	(82,087)	125,450	(1,271,262)
Preferred stock dividends of subsidiaries	228	228	686	686
Net income (loss) attributable to Hawaiian Electric	37,258	(82,315)	124,764	(1,271,948)
Preferred stock dividends of Hawaiian Electric	270	270	810	810
Net income (loss) for common stock	36,988	(82,585)	123,954	(1,272,758)
Consolidating adjustments | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	(3,541)	(2,647)	(10,751)	(2,647)
Expenses
Fuel oil	0	0	0	0
Purchased power	0	0	0	0
Other operation and maintenance	(3,541)	(2,647)	(10,751)	(2,647)
Wildfire tort-related claims		0		0
Depreciation	0	0	0	0
Taxes, other than income taxes	0	0	0	0
Total expenses	(3,541)	(2,647)	(10,751)	(2,647)
Operating income (loss)	0	0	0	0
Allowance for equity funds used during construction	0	0	0	0
Equity in earnings of subsidiaries	(6,123)	18,558	(23,615)	258,633
Retirement defined benefits credit (expense)—other than service costs	0	0	0	0
Interest expense and other charges, net	1,296	1,731	3,631	5,016
Allowance for borrowed funds used during construction	0	0	0	0
Interest income	(1,296)	(1,731)	(3,631)	(5,016)
Income (loss) before income taxes	(6,123)	18,558	(23,615)	258,633
Income tax expense (benefit)	0	0	0	0
Net income (loss)	(6,123)	18,558	(23,615)	258,633
Preferred stock dividends of subsidiaries	0	0	0	0
Net income (loss) attributable to Hawaiian Electric	(6,123)	18,558	(23,615)	258,633
Preferred stock dividends of Hawaiian Electric	0	0	0	0
Net income (loss) for common stock	(6,123)	18,558	(23,615)	258,633
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	560,118	592,784	1,609,625	1,721,592
Expenses
Fuel oil	178,209	207,498	498,376	605,083
Purchased power	132,075	135,645	374,065	390,302
Other operation and maintenance	103,940	105,977	298,628	290,578
Wildfire tort-related claims		130,400		1,500,000
Depreciation	42,576	42,004	127,678	126,011
Taxes, other than income taxes	53,071	55,787	152,587	162,410
Total expenses	509,871	677,311	1,451,334	3,074,384
Operating income (loss)	50,247	(84,527)	158,291	(1,352,792)
Allowance for equity funds used during construction	2,800	2,628	8,432	8,027
Equity in earnings of subsidiaries	6,123	(18,558)	23,615	(258,633)
Retirement defined benefits credit (expense)—other than service costs	867	826	2,678	2,681
Interest expense and other charges, net	(16,654)	(14,870)	(49,966)	(44,879)
Allowance for borrowed funds used during construction	1,172	1,055	3,525	3,168
Interest income	2,404	2,971	7,219	8,606
Income (loss) before income taxes	46,959	(110,475)	153,794	(1,633,822)
Income tax expense (benefit)	9,701	(28,160)	29,030	(361,874)
Net income (loss)	37,258	(82,315)	124,764	(1,271,948)
Preferred stock dividends of subsidiaries	0	0	0	0
Net income (loss) attributable to Hawaiian Electric	37,258	(82,315)	124,764	(1,271,948)
Preferred stock dividends of Hawaiian Electric	270	270	810	810
Net income (loss) for common stock	36,988	(82,585)	123,954	(1,272,758)
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	115,499	123,238	334,783	358,510
Expenses
Fuel oil	22,419	31,464	75,910	91,590
Purchased power	36,008	35,291	89,155	98,415
Other operation and maintenance	26,742	25,614	80,525	74,748
Wildfire tort-related claims		16,300		187,500
Depreciation	11,242	10,964	33,727	32,892
Taxes, other than income taxes	10,779	11,511	31,330	33,411
Total expenses	107,190	131,144	310,647	518,556
Operating income (loss)	8,309	(7,906)	24,136	(160,046)
Allowance for equity funds used during construction	390	256	1,088	893
Equity in earnings of subsidiaries	0	0	0	0
Retirement defined benefits credit (expense)—other than service costs	161	162	497	498
Interest expense and other charges, net	(2,744)	(2,760)	(8,229)	(8,648)
Allowance for borrowed funds used during construction	106	75	297	267
Interest income	320	324	910	720
Income (loss) before income taxes	6,542	(9,849)	18,699	(166,316)
Income tax expense (benefit)	1,407	(2,807)	4,000	(43,636)
Net income (loss)	5,135	(7,042)	14,699	(122,680)
Preferred stock dividends of subsidiaries	133	133	401	400
Net income (loss) attributable to Hawaiian Electric	5,002	(7,175)	14,298	(123,080)
Preferred stock dividends of Hawaiian Electric	0	0	0	0
Net income (loss) for common stock	5,002	(7,175)	14,298	(123,080)
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	112,352	113,840	325,811	330,669
Expenses
Fuel oil	39,919	40,076	115,569	125,313
Purchased power	15,730	18,229	42,273	41,593
Other operation and maintenance	33,816	32,769	91,654	90,485
Wildfire tort-related claims		16,300		187,500
Depreciation	10,204	9,844	30,610	29,533
Taxes, other than income taxes	10,584	10,671	30,577	30,974
Total expenses	110,253	127,889	310,683	505,398
Operating income (loss)	2,099	(14,049)	15,128	(174,729)
Allowance for equity funds used during construction	631	416	1,588	1,356
Equity in earnings of subsidiaries	0	0	0	0
Retirement defined benefits credit (expense)—other than service costs	(30)	(29)	(74)	(76)
Interest expense and other charges, net	(4,012)	(4,324)	(11,708)	(13,114)
Allowance for borrowed funds used during construction	222	201	557	626
Interest income	33	107	159	245
Income (loss) before income taxes	(1,057)	(17,678)	5,650	(185,692)
Income tax expense (benefit)	(686)	(4,966)	294	(49,001)
Net income (loss)	(371)	(12,712)	5,356	(136,691)
Preferred stock dividends of subsidiaries	95	95	285	286
Net income (loss) attributable to Hawaiian Electric	(466)	(12,807)	5,071	(136,977)
Preferred stock dividends of Hawaiian Electric	0	0	0	0
Net income (loss) for common stock	(466)	(12,807)	5,071	(136,977)
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	3,000	2,402	8,808	2,402
Expenses
Fuel oil	0	0	0	0
Purchased power	0	0	0	0
Other operation and maintenance	862	484	3,088	484
Wildfire tort-related claims		0		0
Depreciation	0	0	0	0
Taxes, other than income taxes	0	0	1	0
Total expenses	862	484	3,089	484
Operating income (loss)	2,138	1,918	5,719	1,918
Allowance for equity funds used during construction	0	0	0	0
Equity in earnings of subsidiaries	0	0	0	0
Retirement defined benefits credit (expense)—other than service costs	0	0	0	0
Interest expense and other charges, net	0	0	0	0
Allowance for borrowed funds used during construction	0	0	0	0
Interest income	0	0	0	0
Income (loss) before income taxes	2,138	1,918	5,719	1,918
Income tax expense (benefit)	551	494	1,473	494
Net income (loss)	1,587	1,424	4,246	1,424
Preferred stock dividends of subsidiaries	0	0	0	0
Net income (loss) attributable to Hawaiian Electric	1,587	1,424	4,246	1,424
Preferred stock dividends of Hawaiian Electric	0	0	0	0
Net income (loss) for common stock	$ 1,587	$ 1,424	$ 4,246	$ 1,424