Electric utility segment - Condensed Consolidating Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Income Statements, Captions [Line Items]
Revenues	$ 897,158	$ 928,237
Expenses
Total expenses	820,739	834,719
Operating income	76,419	93,518
Allowance for equity funds used during construction	3,640	3,301
Retirement defined benefits credit (expense)—other than service costs	1,282	1,152
Allowance for borrowed funds used during construction	1,386	1,131
Interest income	3,133	0
Income before income taxes	54,269	70,304
Income taxes	11,674	15,110
Net income (loss)	42,595	55,194
Preferred stock dividends of Hawaiian Electric	473	473
Net income for common stock	42,122	54,721
Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	788,578	830,361
Expenses
Fuel oil	284,296	334,097
Purchased power	159,817	152,761
Other operation and maintenance	143,890	128,316
Depreciation	62,812	60,927
Taxes, other than income taxes	74,408	78,385
Total expenses	725,223	754,486
Operating income	63,355	75,875
Allowance for equity funds used during construction	3,640	3,301
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	1,072	1,047
Interest expense and other charges, net	(19,985)	(20,246)
Allowance for borrowed funds used during construction	1,386	1,131
Interest income	1,432	0
Income before income taxes	50,900	61,108
Income taxes	11,180	13,600
Net income	39,720	47,508
Preferred stock dividends of subsidiaries	229	229
Net income (loss)	39,491	47,279
Preferred stock dividends of Hawaiian Electric	270	270
Net income for common stock	39,221	47,009
Reportable Legal Entities | Hawaiian Electric Consolidated
Expenses
Interest income	1,432
Consolidating adjustments | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	0	(130)
Expenses
Fuel oil	0	0
Purchased power	0	0
Other operation and maintenance	0	0
Depreciation	0	0
Taxes, other than income taxes	0	0
Total expenses	0	0
Operating income	0	(130)
Allowance for equity funds used during construction	0	0
Equity in earnings of subsidiaries	(6,024)	(11,541)
Retirement defined benefits credit (expense)—other than service costs	0	0
Interest expense and other charges, net	1,452	130
Allowance for borrowed funds used during construction	0	0
Interest income	(1,452)
Income before income taxes	(6,024)	(11,541)
Income taxes	0	0
Net income	(6,024)	(11,541)
Preferred stock dividends of subsidiaries	0	0
Net income (loss)	(6,024)	(11,541)
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	(6,024)	(11,541)
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	564,180	601,530
Expenses
Fuel oil	210,199	253,827
Purchased power	117,518	110,279
Other operation and maintenance	90,884	83,233
Depreciation	42,004	41,038
Taxes, other than income taxes	53,409	56,953
Total expenses	514,014	545,330
Operating income	50,166	56,200
Allowance for equity funds used during construction	2,821	2,640
Equity in earnings of subsidiaries	6,024	11,541
Retirement defined benefits credit (expense)—other than service costs	927	904
Interest expense and other charges, net	(14,292)	(14,557)
Allowance for borrowed funds used during construction	1,079	918
Interest income	2,663
Income before income taxes	49,388	57,646
Income taxes	9,897	10,367
Net income	39,491	47,279
Preferred stock dividends of subsidiaries	0	0
Net income (loss)	39,491	47,279
Preferred stock dividends of Hawaiian Electric	270	270
Net income for common stock	39,221	47,009
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	117,609	115,288
Expenses
Fuel oil	31,185	27,760
Purchased power	32,056	34,086
Other operation and maintenance	24,590	21,350
Depreciation	10,964	10,635
Taxes, other than income taxes	10,957	10,737
Total expenses	109,752	104,568
Operating income	7,857	10,720
Allowance for equity funds used during construction	349	284
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	168	169
Interest expense and other charges, net	(2,914)	(2,831)
Allowance for borrowed funds used during construction	107	91
Interest income	155
Income before income taxes	5,722	8,433
Income taxes	1,198	1,909
Net income	4,524	6,524
Preferred stock dividends of subsidiaries	134	134
Net income (loss)	4,390	6,390
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	4,390	6,390
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	106,789	113,673
Expenses
Fuel oil	42,912	52,510
Purchased power	10,243	8,396
Other operation and maintenance	28,416	23,733
Depreciation	9,844	9,254
Taxes, other than income taxes	10,042	10,695
Total expenses	101,457	104,588
Operating income	5,332	9,085
Allowance for equity funds used during construction	470	377
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit (expense)—other than service costs	(23)	(26)
Interest expense and other charges, net	(4,231)	(2,988)
Allowance for borrowed funds used during construction	200	122
Interest income	66
Income before income taxes	1,814	6,570
Income taxes	85	1,324
Net income	1,729	5,246
Preferred stock dividends of subsidiaries	95	95
Net income (loss)	1,634	5,151
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	1,634	5,151
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	0	0
Expenses
Fuel oil	0	0
Purchased power	0	0
Other operation and maintenance	0	0
Depreciation	0	0
Taxes, other than income taxes	0	0
Total expenses	0	0
Operating income	0	0
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
Income before income taxes	0	0
Income taxes	0	0
Net income	0	0
Preferred stock dividends of subsidiaries	0	0
Net income (loss)	0	0
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	0	$ 0
Other subsidiaries | Consolidating adjustments | Hawaiian Electric Consolidated
Expenses
Interest income	$ 0