Electric utility segment - Condensed Consolidating Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	$ (104,402)	$ (1,295,484)	$ 42,122	$ 41,118	$ 54,610	$ 54,721	$ (1,357,764)	$ 150,449
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	(1,244)			(446)			(2,138)	(1,160)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	1,333			470			2,251	1,321
Other comprehensive income (loss), net of taxes	39,360	1,594	(9,801)	(34,875)	(7,609)	20,488	31,153	(21,996)
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(65,042)			6,243			(1,326,611)	128,453
Hawaiian Electric Consolidated
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	(82,585)	(1,229,394)	39,221	43,461	45,299	47,009	(1,272,758)	135,769
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	(1,331)			(547)			(2,344)	(1,487)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	1,333			470			2,251	1,321
Other comprehensive income (loss), net of taxes	2	$ (46)	$ (49)	(77)	$ (44)	$ (45)	(93)	(166)
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(82,583)			43,384			(1,272,851)	135,603
Consolidating adjustments | Hawaiian Electric Consolidated
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	18,558			(3,005)			258,633	(25,960)
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	111			126			304	366
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	(106)			(117)			(275)	(334)
Other comprehensive income (loss), net of taxes	5			9			29	32
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	18,563			(2,996)			258,662	(25,928)
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	(82,585)			43,461			(1,272,758)	135,769
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	(1,331)			(547)			(2,344)	(1,487)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	1,333			470			2,251	1,321
Other comprehensive income (loss), net of taxes	2			(77)			(93)	(166)
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(82,583)			43,384			(1,272,851)	135,603
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	(7,175)			7,419			(123,080)	20,884
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	(40)			(55)			(117)	(166)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	42			54			112	157
Other comprehensive income (loss), net of taxes	2			(1)			(5)	(9)
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(7,173)			7,418			(123,085)	20,875
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	(12,807)			(4,414)			(136,977)	5,076
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	(71)			(71)			(187)	(200)
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	64			63			163	177
Other comprehensive income (loss), net of taxes	(7)			(8)			(24)	(23)
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(12,814)			(4,422)			(137,001)	5,053
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated
Condensed Statement of Income Captions [Line Items]
Net income (loss) for common stock	1,424			0			1,424	0
Retirement benefit plans:
Adjustment for amortization of prior service credit and net gains recognized during the period in net periodic benefit cost, net of taxes of $(431), $(153), $(740) and $(397), respectively	0			0			0	0
Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	0			0			0	0
Other comprehensive income (loss), net of taxes	0			0			0	0
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	$ 1,424			$ 0			$ 1,424	$ 0