Electric utility segment - Schedule of Condensed Consolidating Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Condensed Statement of Income Captions [Line Items]
Net income for common stock	$ 30,450	$ 26,671
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	(458)	(505)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	436	483
Other comprehensive loss, net of tax benefits	(74)	(460)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	30,376	26,211
Hawaiian Electric consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	35,343	47,816
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	(483)	(530)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	436	483
Other comprehensive loss, net of tax benefits	(47)	(47)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	35,296	47,769
Consolidating adjustments | Hawaiian Electric consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	(7,174)	(9,725)
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	105	94
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	(89)	(76)
Other comprehensive loss, net of tax benefits	16	18
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	(7,158)	(9,707)
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	35,343	47,816
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	(483)	(530)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	436	483
Other comprehensive loss, net of tax benefits	(47)	(47)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	35,296	47,769
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	3,558	3,596
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	(39)	(29)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	35	22
Other comprehensive loss, net of tax benefits	(4)	(7)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	3,554	3,589
Maui Electric | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	2,126	4,436
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	(66)	(65)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	54	54
Other comprehensive loss, net of tax benefits	(12)	(11)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	2,114	4,425
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	1,490	1,693
Retirement benefit plans:
Adjustment for amortization of net gains recognized during the period in net periodic benefit cost, net of taxes	0	0
Reclassification adjustment for impact of D&Os of the PUC included in regulatory accounts, net of taxes	0	0
Other comprehensive loss, net of tax benefits	0	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	$ 1,490	$ 1,693