Electric utility segment - Condensed consolidating statement of income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Condensed Income Statements, Captions [Line Items]
Revenues	$ 895,607		$ 680,257		$ 1,680,675	$ 1,323,203
Expenses
Total expenses	808,939		578,401		1,494,731	1,123,316
Total operating income	86,668		101,856		185,944	199,887
Allowance for equity funds used during construction	2,470		2,377		4,879	4,568
Retirement defined benefits credit—other than service costs	1,246		1,216		2,489	3,651
Allowance for borrowed funds used during construction	798		812		1,576	1,559
Income before income taxes	66,217		82,944		153,697	163,140
Income taxes	13,203		18,599		31,043	33,964
Net income attributable to Hawaiian Electric	53,014		64,345		122,654	129,176
Preferred stock dividends of Hawaiian Electric	473		473		946	946
Net income for common stock	52,541	$ 69,167	63,872	$ 64,358	121,708	128,230
Consolidating adjustments
Expenses
Total expenses			0
Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	818,873		601,879		1,527,665	1,166,743
Expenses
Fuel oil	269,655		139,136		490,941	266,563
Purchased power	218,085		162,465		381,618	304,761
Other operation and maintenance	124,892		118,142		250,149	232,712
Depreciation	58,739		57,381		117,210	114,736
Taxes, other than income taxes	76,348		57,071		142,998	111,173
Total expenses	747,719		534,195		1,382,916	1,029,945
Total operating income	71,154		67,684		144,749	136,798
Allowance for equity funds used during construction	2,470		2,377		4,879	4,568
Equity in earnings of subsidiaries	0		0		0	0
Retirement defined benefits credit—other than service costs	991		1,020		1,981	2,041
Interest expense and other charges, net	(18,800)		(17,995)		(37,126)	(35,978)
Allowance for borrowed funds used during construction	798		812		1,576	1,559
Income before income taxes	56,613		53,898		116,059	108,988
Income taxes	11,979		11,498		24,517	22,731
Net income	44,634		42,400		91,542	86,257
Preferred stock dividends of subsidiaries	229		229		458	458
Net income attributable to Hawaiian Electric	44,405		42,171		91,084	85,799
Preferred stock dividends of Hawaiian Electric	270		270		540	540
Net income for common stock	44,135	$ 46,409	41,901	$ 43,358	90,544	85,259
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaiian Electric
Condensed Income Statements, Captions [Line Items]
Revenues	576,472		422,697		1,076,714	823,251
Expenses
Fuel oil	184,297		91,345		338,722	180,073
Purchased power	165,202		124,948		289,385	233,552
Other operation and maintenance	82,707		77,903		166,363	155,238
Depreciation	39,501		38,907		78,985	77,821
Taxes, other than income taxes	54,025		40,301		101,299	78,928
Total expenses	525,732		373,404		974,754	725,612
Total operating income	50,740		49,293		101,960	97,639
Allowance for equity funds used during construction	1,946		1,930		3,936	3,678
Equity in earnings of subsidiaries	12,237		10,744		25,898	23,254
Retirement defined benefits credit—other than service costs	856		884		1,711	1,770
Interest expense and other charges, net	(13,519)		(12,829)		(26,612)	(25,661)
Allowance for borrowed funds used during construction	637		654		1,288	1,245
Income before income taxes	52,897		50,676		108,181	101,925
Income taxes	8,492		8,505		17,097	16,126
Net income	44,405		42,171		91,084	85,799
Preferred stock dividends of subsidiaries	0		0		0	0
Net income attributable to Hawaiian Electric	44,405		42,171		91,084	85,799
Preferred stock dividends of Hawaiian Electric	270		270		540	540
Net income for common stock	44,135		41,901		90,544	85,259
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaii Electric Light
Condensed Income Statements, Captions [Line Items]
Revenues	124,502		91,512		233,030	176,661
Expenses
Fuel oil	33,065		19,586		58,316	36,071
Purchased power	38,735		24,236		69,447	45,833
Other operation and maintenance	21,331		19,474		41,545	37,386
Depreciation	10,352		10,053		20,703	20,101
Taxes, other than income taxes	11,378		8,539		21,410	16,532
Total expenses	114,861		81,888		211,421	155,923
Total operating income	9,641		9,624		21,609	20,738
Allowance for equity funds used during construction	217		140		410	272
Equity in earnings of subsidiaries	0		0		0	0
Retirement defined benefits credit—other than service costs	167		169		334	337
Interest expense and other charges, net	(2,642)		(2,573)		(5,251)	(5,154)
Allowance for borrowed funds used during construction	67		48		127	92
Income before income taxes	7,450		7,408		17,229	16,285
Income taxes	1,659		1,668		3,927	3,719
Net income	5,791		5,740		13,302	12,566
Preferred stock dividends of subsidiaries	133		133		267	267
Net income attributable to Hawaiian Electric	5,658		5,607		13,035	12,299
Preferred stock dividends of Hawaiian Electric	0		0		0	0
Net income for common stock	5,658		5,607		13,035	12,299
Hawaiian Electric Consolidated | Reportable Legal Entities | Maui Electric
Condensed Income Statements, Captions [Line Items]
Revenues	117,928		87,670		217,956	166,851
Expenses
Fuel oil	52,293		28,205		93,903	50,419
Purchased power	14,148		13,281		22,786	25,376
Other operation and maintenance	20,854		20,765		42,241	40,088
Depreciation	8,886		8,421		17,522	16,814
Taxes, other than income taxes	10,945		8,231		20,289	15,713
Total expenses	107,126		78,903		196,741	148,410
Total operating income	10,802		8,767		21,215	18,441
Allowance for equity funds used during construction	307		307		533	618
Equity in earnings of subsidiaries	0		0		0	0
Retirement defined benefits credit—other than service costs	(32)		(33)		(64)	(66)
Interest expense and other charges, net	(2,668)		(2,593)		(5,298)	(5,183)
Allowance for borrowed funds used during construction	94		110		161	222
Income before income taxes	8,503		6,558		16,547	14,032
Income taxes	1,828		1,325		3,493	2,886
Net income	6,675		5,233		13,054	11,146
Preferred stock dividends of subsidiaries	96		96		191	191
Net income attributable to Hawaiian Electric	6,579		5,137		12,863	10,955
Preferred stock dividends of Hawaiian Electric	0		0		0	0
Net income for common stock	6,579		5,137		12,863	10,955
Hawaiian Electric Consolidated | Reportable Legal Entities | Other subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	0		0		0	0
Expenses
Fuel oil	0		0		0	0
Purchased power	0		0		0	0
Other operation and maintenance	0		0		0	0
Depreciation	0		0		0	0
Taxes, other than income taxes	0		0		0	0
Total expenses	0		0		0	0
Total operating income	0		0		0	0
Allowance for equity funds used during construction	0		0		0	0
Equity in earnings of subsidiaries	0		0		0	0
Retirement defined benefits credit—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
Income before income taxes	0		0		0	0
Income taxes	0		0		0	0
Net income	0		0		0	0
Preferred stock dividends of subsidiaries	0		0		0	0
Net income attributable to Hawaiian Electric	0		0		0	0
Preferred stock dividends of Hawaiian Electric	0		0		0	0
Net income for common stock	0		0		0	0
Hawaiian Electric Consolidated | Consolidating adjustments
Condensed Income Statements, Captions [Line Items]
Revenues	(29)		0		(35)	(20)
Expenses
Fuel oil	0		0		0	0
Purchased power	0		0		0	0
Other operation and maintenance	0		0		0	0
Depreciation	0		0		0	0
Taxes, other than income taxes	0		0		0	0
Total expenses	0				0	0
Total operating income	(29)		0		(35)	(20)
Allowance for equity funds used during construction	0		0		0	0
Equity in earnings of subsidiaries	(12,237)		(10,744)		(25,898)	(23,254)
Retirement defined benefits credit—other than service costs	0		0		0	0
Interest expense and other charges, net	29		0		35	20
Allowance for borrowed funds used during construction	0		0		0	0
Income before income taxes	(12,237)		(10,744)		(25,898)	(23,254)
Income taxes	0		0		0	0
Net income	(12,237)		(10,744)		(25,898)	(23,254)
Preferred stock dividends of subsidiaries	0		0		0	0
Net income attributable to Hawaiian Electric	(12,237)		(10,744)		(25,898)	(23,254)
Preferred stock dividends of Hawaiian Electric	0		0		0	0
Net income for common stock	$ (12,237)		$ (10,744)		$ (25,898)	$ (23,254)