Electric utility segment - Schedule of Condensed Consolidating Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Condensed Income Statements, Captions [Line Items]
Revenues	$ 746,447	$ 744,070
Expenses
Total expenses	693,070	681,650
Operating income (loss)	53,377	62,420
Allowance for equity funds used during construction	3,764	3,585
Retirement defined benefits credit (expense)—other than service costs	879	917
Allowance for borrowed funds used during construction	1,705	1,417
Interest income	9,995	12,623
Income before income taxes	38,592	33,539
Income tax expense	8,142	6,395
Net income attributable to Hawaiian Electric	30,450	27,144
Preferred stock dividends of Hawaiian Electric	0	473
Net income for common stock	30,450	26,671
Hawaiian Electric consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	744,040	738,366
Expenses
Fuel oil	236,913	238,721
Purchased power	145,274	146,717
Other operation and maintenance	162,217	143,108
Depreciation	66,446	64,019
Taxes, other than income taxes	70,657	69,864
Total expenses	681,507	662,429
Operating income (loss)	62,533	75,937
Allowance for equity funds used during construction	3,764	3,585
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	1,050	1,051
Interest expense and other charges, net	(27,876)	(22,452)
Allowance for borrowed funds used during construction	1,705	1,417
Interest income	3,868	1,981
Income before income taxes	45,044	61,519
Income tax expense	9,701	13,204
Net income	35,343	48,315
Preferred stock dividends of subsidiaries	0	229
Net income attributable to Hawaiian Electric	35,343	48,086
Preferred stock dividends of Hawaiian Electric	0	270
Net income for common stock	35,343	47,816
Consolidating adjustments | Hawaiian Electric consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	(3,494)	(3,294)
Expenses
Fuel oil	0	0
Purchased power	0	0
Other operation and maintenance	(3,494)	(3,294)
Depreciation	0	0
Taxes, other than income taxes	0	0
Total expenses	(3,494)	(3,294)
Operating income (loss)	0	0
Allowance for equity funds used during construction	0	0
Equity in earnings of subsidiaries	(7,174)	(9,725)
Retirement defined benefits credit (expense)—other than service costs	0	0
Interest expense and other charges, net	2,019	1,123
Allowance for borrowed funds used during construction	0	0
Interest income	(2,019)	(1,123)
Income before income taxes	(7,174)	(9,725)
Income tax expense	0	0
Net income	(7,174)	(9,725)
Preferred stock dividends of subsidiaries		0
Net income attributable to Hawaiian Electric		(9,725)
Preferred stock dividends of Hawaiian Electric		0
Net income for common stock	(7,174)	(9,725)
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	528,359	524,703
Expenses
Fuel oil	176,678	171,793
Purchased power	102,996	110,731
Other operation and maintenance	106,440	91,493
Depreciation	44,079	42,573
Taxes, other than income taxes	50,271	49,779
Total expenses	480,464	466,369
Operating income (loss)	47,895	58,334
Allowance for equity funds used during construction	2,818	2,795
Equity in earnings of subsidiaries	7,174	9,725
Retirement defined benefits credit (expense)—other than service costs	903	905
Interest expense and other charges, net	(22,151)	(17,024)
Allowance for borrowed funds used during construction	1,281	1,168
Interest income	5,468	2,788
Income before income taxes	43,388	58,691
Income tax expense	8,045	10,605
Net income	35,343	48,086
Preferred stock dividends of subsidiaries		0
Net income attributable to Hawaiian Electric		48,086
Preferred stock dividends of Hawaiian Electric		270
Net income for common stock	35,343	47,816
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	110,122	108,311
Expenses
Fuel oil	21,832	26,794
Purchased power	31,614	25,490
Other operation and maintenance	27,970	28,034
Depreciation	11,670	11,243
Taxes, other than income taxes	10,338	10,179
Total expenses	103,424	101,740
Operating income (loss)	6,698	6,571
Allowance for equity funds used during construction	304	347
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	170	168
Interest expense and other charges, net	(3,194)	(2,747)
Allowance for borrowed funds used during construction	88	95
Interest income	378	229
Income before income taxes	4,444	4,663
Income tax expense	886	933
Net income	3,558	3,730
Preferred stock dividends of subsidiaries		134
Net income attributable to Hawaiian Electric		3,596
Preferred stock dividends of Hawaiian Electric		0
Net income for common stock	3,558	3,596
Maui Electric | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	106,099	105,702
Expenses
Fuel oil	38,403	40,134
Purchased power	10,664	10,496
Other operation and maintenance	30,354	26,211
Depreciation	10,697	10,203
Taxes, other than income taxes	10,048	9,906
Total expenses	100,166	96,950
Operating income (loss)	5,933	8,752
Allowance for equity funds used during construction	642	443
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	(23)	(22)
Interest expense and other charges, net	(4,550)	(3,804)
Allowance for borrowed funds used during construction	336	154
Interest income	41	87
Income before income taxes	2,379	5,610
Income tax expense	253	1,079
Net income	2,126	4,531
Preferred stock dividends of subsidiaries		95
Net income attributable to Hawaiian Electric		4,436
Preferred stock dividends of Hawaiian Electric		0
Net income for common stock	2,126	4,436
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	2,954	2,944
Expenses
Fuel oil	0	0
Purchased power	0	0
Other operation and maintenance	947	664
Depreciation	0	0
Taxes, other than income taxes	0	0
Total expenses	947	664
Operating income (loss)	2,007	2,280
Allowance for equity funds used during construction	0	0
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	0	0
Interest expense and other charges, net	0	0
Allowance for borrowed funds used during construction	0	0
Interest income	0	0
Income before income taxes	2,007	2,280
Income tax expense	517	587
Net income	1,490	1,693
Preferred stock dividends of subsidiaries		0
Net income attributable to Hawaiian Electric		1,693
Preferred stock dividends of Hawaiian Electric		0
Net income for common stock	$ 1,490	$ 1,693