Electric utility segment - Consolidating Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Income Statements, Captions [Line Items]
Revenues	$ 2,850,379	$ 2,579,775	$ 2,873,948
Expenses
Total expenses	2,464,313	2,268,282	2,525,927
Operating income	386,066	311,493	348,021
Allowance for equity funds used during construction	9,534	8,768	11,987
Retirement defined benefits credit (expense)—other than service costs	5,848	(3,210)	(2,806)
Allowance for borrowed funds used during construction	3,250	2,992	4,453
Income before income taxes	310,863	240,624	271,409
Income taxes	62,807	40,910	51,637
Net income (loss)	248,056	199,714	219,772
Preferred stock dividends of subsidiaries	1,890	1,890	1,890
Net income for common stock	246,166	197,824	217,882
Hawaiian Electric (parent only)
Expenses
Total expenses	24,934	21,870	20,335
Retirement defined benefits credit (expense)—other than service costs	114	(634)	(442)
Income before income taxes	235,584	186,565	208,075
Income taxes	(10,582)	(11,259)	(9,807)
Net income (loss)	246,166	197,824	217,882
Hawaiian Electric Company, Inc. and Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	2,539,636	2,265,320	2,545,942
Expenses
Fuel oil	644,349	515,274	720,709
Purchased power	670,494	568,749	633,256
Other operation and maintenance	475,412	474,192	481,737
Depreciation	229,469	222,733	215,731
Taxes, other than income taxes	240,354	215,822	240,131
Total expenses	2,260,078	1,996,770	2,291,564
Operating income	279,558	268,550	254,378
Allowance for equity funds used during construction	9,534	8,768	11,987
Equity in earnings of subsidiaries	0	0	0
Retirement defined benefits credit (expense)—other than service costs	3,890	(763)	(2,836)
Interest expense and other charges, net	(72,447)	(67,794)	(70,842)
Allowance for borrowed funds used during construction	3,250	2,992	4,453
Income before income taxes	223,785	211,753	197,140
Income taxes	44,148	40,418	38,305
Net income (loss)	179,637	171,335	158,835
Preferred stock dividends of subsidiaries	915	915	915
Net income attributable to Hawaiian Electric	178,722	170,420	157,920
Preferred stock dividends of Hawaiian Electric	1,080	1,080	1,080
Net income for common stock	177,642	169,340	156,840
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Hawaiian Electric (parent only)
Condensed Income Statements, Captions [Line Items]
Revenues	1,793,372	1,608,305	1,803,698
Expenses
Fuel oil	442,818	354,087	494,728
Purchased power	508,642	446,672	494,215
Other operation and maintenance	313,009	311,781	319,771
Depreciation	155,607	151,387	143,470
Taxes, other than income taxes	170,604	154,191	170,979
Total expenses	1,590,680	1,418,118	1,623,163
Operating income	202,692	190,187	180,535
Allowance for equity funds used during construction	7,734	7,335	9,955
Equity in earnings of subsidiaries	45,353	47,504	43,167
Retirement defined benefits credit (expense)—other than service costs	3,348	(1,294)	(2,287)
Interest expense and other charges, net	(51,680)	(48,775)	(51,199)
Allowance for borrowed funds used during construction	2,617	2,540	3,666
Income before income taxes	210,064	197,497	183,837
Income taxes	31,342	27,077	25,917
Net income (loss)	178,722	170,420	157,920
Preferred stock dividends of subsidiaries	0	0	0
Net income attributable to Hawaiian Electric	178,722	170,420	157,920
Preferred stock dividends of Hawaiian Electric	1,080	1,080	1,080
Net income for common stock	177,642	169,340	156,840
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Hawaii Electric Light
Condensed Income Statements, Captions [Line Items]
Revenues	381,033	334,221	364,590
Expenses
Fuel oil	80,086	72,202	84,565
Purchased power	108,997	73,120	90,989
Other operation and maintenance	79,390	73,746	76,091
Depreciation	40,201	39,041	41,812
Taxes, other than income taxes	35,499	31,181	33,787
Total expenses	344,173	289,290	327,244
Operating income	36,860	44,931	37,346
Allowance for equity funds used during construction	586	543	816
Equity in earnings of subsidiaries	0	0	0
Retirement defined benefits credit (expense)—other than service costs	670	672	(422)
Interest expense and other charges, net	(10,353)	(10,004)	(10,741)
Allowance for borrowed funds used during construction	197	160	342
Income before income taxes	27,960	36,302	27,341
Income taxes	6,246	8,275	5,990
Net income (loss)	21,714	28,027	21,351
Preferred stock dividends of subsidiaries	534	534	534
Net income attributable to Hawaiian Electric	21,180	27,493	20,817
Preferred stock dividends of Hawaiian Electric	0	0	0
Net income for common stock	21,180	27,493	20,817
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Maui Electric
Condensed Income Statements, Captions [Line Items]
Revenues	365,256	323,430	378,202
Expenses
Fuel oil	121,445	88,985	141,416
Purchased power	52,855	48,957	48,052
Other operation and maintenance	83,013	88,665	85,875
Depreciation	33,661	32,305	30,449
Taxes, other than income taxes	34,251	30,450	35,365
Total expenses	325,225	289,362	341,157
Operating income	40,031	34,068	37,045
Allowance for equity funds used during construction	1,214	890	1,216
Equity in earnings of subsidiaries	0	0	0
Retirement defined benefits credit (expense)—other than service costs	(128)	(141)	(127)
Interest expense and other charges, net	(10,439)	(9,651)	(9,450)
Allowance for borrowed funds used during construction	436	292	445
Income before income taxes	31,114	25,458	29,129
Income taxes	6,560	5,066	6,398
Net income (loss)	24,554	20,392	22,731
Preferred stock dividends of subsidiaries	381	381	381
Net income attributable to Hawaiian Electric	24,173	20,011	22,350
Preferred stock dividends of Hawaiian Electric	0	0	0
Net income for common stock	24,173	20,011	22,350
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Other subsidiaries
Expenses
Allowance for equity funds used during construction	0	0	0
Net income (loss)	0	0	0
Hawaiian Electric Company, Inc. and Subsidiaries | Consolidating adjustments
Condensed Income Statements, Captions [Line Items]
Revenues	(25)	(636)	(548)
Expenses
Fuel oil	0	0	0
Purchased power	0	0	0
Other operation and maintenance	0	0	0
Depreciation	0	0	0
Taxes, other than income taxes	0	0	0
Total expenses	0	0	0
Operating income	(25)	(636)	(548)
Allowance for equity funds used during construction	0	0	0
Equity in earnings of subsidiaries	(45,353)	(47,504)	(43,167)
Retirement defined benefits credit (expense)—other than service costs	0	0	0
Interest expense and other charges, net	25	636	548
Allowance for borrowed funds used during construction	0	0	0
Income before income taxes	(45,353)	(47,504)	(43,167)
Income taxes	0	0	0
Net income (loss)	(45,353)	(47,504)	(43,167)
Preferred stock dividends of subsidiaries	0	0	0
Net income attributable to Hawaiian Electric	(45,353)	(47,504)	(43,167)
Preferred stock dividends of Hawaiian Electric	0	0	0
Net income for common stock	$ (45,353)	$ (47,504)	$ (43,167)