Retirement benefits - Schedule of Changes in Projected Benefit Obligations and Fair Value of Plan Assets and Amounts Recognized in OCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined benefit pension and other postretirement benefit plans asset	$ 219,211	$ 107,335
Defined benefit plans liability	(23,656)	(23,213)
Hawaiian Electric Company, Inc. and Subsidiaries
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined benefit pension and other postretirement benefit plans asset	219,477	108,819
Defined benefit plans liability	(6,909)	(6,428)
Pension benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	1,893,577	2,032,978
Service cost	41,064	45,821	$ 45,228
Interest cost	107,502	101,882	98,606
Actuarial loss (gain)	22,531	(106,453)
Participants contributions	0	0
Benefits paid and expenses	(103,823)	(99,494)
Benefit obligation, balance at the end of the period	1,960,851	1,893,577	2,032,978
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	1,888,853	1,973,539
Actual return on plan assets	243,337	105,938
Employer contributions	11,573	8,778
Participants contributions	0	0
Benefits paid and expenses	(102,067)	(97,735)
Fair value of plan assets, balance at the end of the period	2,041,696	1,888,853	1,973,539
Accrued benefit asset (liability), balance	80,845	(4,724)
Defined benefit pension and other postretirement benefit plans asset	106,285	20,269
Other liabilities (short-term)	(1,793)	(1,780)
Defined benefit plans liability	(23,647)	(23,213)
Accrued benefit asset, December 31	80,845	(4,724)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income [Roll Forward]
AOCI debit/(credit), balance at beginning of the period (excluding impact of PUC D&Os)	(963)	85,262
Recognized during year – net actuarial gain (loss)	(283)	(359)
Occurring during year – net actuarial gain	(85,398)	(73,969)
Adjustment from discontinued operations	0	(11,897)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(86,644)	(963)	85,262
Cumulative impact of PUC D&Os	90,015	5,999
AOCI debit/(credit), balance at end of the period	3,371	5,036
Net actuarial gain	(86,644)	(963)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(86,644)	(963)	85,262
Income taxes (benefits)	(868)	(1,297)
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	2,503	3,739
Pension benefits | Continuing Operations
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	1,893,577	1,951,821
Benefit obligation, balance at the end of the period		1,893,577	1,951,821
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	1,888,853	1,871,872
Fair value of plan assets, balance at the end of the period		1,888,853	1,871,872
Pension benefits | Discontinued Operations
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	0	81,157
Change in projected benefit obligations - discontinued operations	0	(81,157)
Benefit obligation, balance at the end of the period		0	81,157
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	0	101,667
Change in plan assets - discontinued operations	0	(101,667)
Fair value of plan assets, balance at the end of the period		0	101,667
Pension benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	1,830,454	1,888,463
Service cost	40,086	44,669	44,143
Interest cost	103,947	98,492	95,351
Actuarial loss (gain)	21,825	(104,692)
Participants contributions	0	0
Benefits paid and expenses	(99,713)	(95,785)
Transfers	0	(693)
Benefit obligation, balance at the end of the period	1,896,599	1,830,454	1,888,463
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	1,843,676	1,827,285
Actual return on plan assets	237,568	103,457
Employer contributions	11,439	8,733
Participants contributions	0	0
Benefits paid and expenses	(99,199)	(95,261)
Other	0	(538)
Fair value of plan assets, balance at the end of the period	1,993,484	1,843,676	1,827,285
Accrued benefit asset (liability), balance	96,885	13,222
Defined benefit pension and other postretirement benefit plans asset	104,308	20,164
Other liabilities (short-term)	(514)	(514)
Defined benefit plans liability	(6,909)	(6,428)
Accrued benefit asset, December 31	96,885	13,222
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income [Roll Forward]
AOCI debit/(credit), balance at beginning of the period (excluding impact of PUC D&Os)	(3,975)	69,339
Recognized during year – net actuarial gain (loss)	(108)	(99)
Occurring during year – net actuarial gain	(83,555)	(73,215)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(87,638)	(3,975)	69,339
Cumulative impact of PUC D&Os	90,015	5,999
AOCI debit/(credit), balance at end of the period	2,377	2,024
Net actuarial gain	(87,638)	(3,975)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(87,638)	(3,975)	69,339
Income taxes (benefits)	(612)	(522)
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	1,765	1,502
Other benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	131,903	143,343
Service cost	988	1,112	1,430
Interest cost	7,291	7,365	8,497
Actuarial loss (gain)	(745)	(9,913)
Participants contributions	3,625	4,024
Benefits paid and expenses	(13,083)	(13,594)
Benefit obligation, balance at the end of the period	129,979	131,903	143,343
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	217,890	207,372
Actual return on plan assets	32,782	19,438
Employer contributions	0	0
Participants contributions	3,625	4,024
Benefits paid and expenses	(12,394)	(12,944)
Fair value of plan assets, balance at the end of the period	241,903	217,890	207,372
Accrued benefit asset (liability), balance	111,924	85,987
Defined benefit pension and other postretirement benefit plans asset	112,926	87,066
Other liabilities (short-term)	(1,002)	(1,079)
Defined benefit plans liability	0	0
Accrued benefit asset, December 31	111,924	85,987
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income [Roll Forward]
AOCI debit/(credit), balance at beginning of the period (excluding impact of PUC D&Os)	(61,979)	(49,618)
Recognized during year – net actuarial gain (loss)	3,052	2,898
Occurring during year – net actuarial gain	(19,486)	(15,401)
Adjustment from discontinued operations	0	142
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(78,413)	(61,979)	(49,618)
Cumulative impact of PUC D&Os	71,355	55,140
AOCI debit/(credit), balance at end of the period	(7,058)	(6,839)
Net actuarial gain	(78,413)	(61,979)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(78,413)	(61,979)	(49,618)
Income taxes (benefits)	1,818	1,761
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	(5,240)	(5,078)
Other benefits | Continuing Operations
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	131,903	142,909
Benefit obligation, balance at the end of the period		131,903	142,909
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	217,890	207,372
Fair value of plan assets, balance at the end of the period		217,890	207,372
Other benefits | Discontinued Operations
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	0	434
Change in projected benefit obligations - discontinued operations	0	(434)
Benefit obligation, balance at the end of the period		0	434
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	0	0
Change in plan assets - discontinued operations	0	0
Fair value of plan assets, balance at the end of the period		0	0
Other benefits | Hawaiian Electric Company, Inc. and Subsidiaries
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	126,088	136,572
Service cost	976	1,096	1,415
Interest cost	6,949	7,039	8,143
Actuarial loss (gain)	(937)	(9,688)
Participants contributions	3,568	3,951
Benefits paid and expenses	(12,507)	(12,835)
Transfers	0	(47)
Benefit obligation, balance at the end of the period	124,137	126,088	136,572
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	214,743	204,140
Actual return on plan assets	32,331	19,299
Employer contributions	0	0
Participants contributions	3,568	3,951
Benefits paid and expenses	(12,098)	(12,600)
Other	0	(47)
Fair value of plan assets, balance at the end of the period	238,544	214,743	204,140
Accrued benefit asset (liability), balance	114,407	88,655
Defined benefit pension and other postretirement benefit plans asset	115,169	88,655
Other liabilities (short-term)	(762)	0
Defined benefit plans liability	0	0
Accrued benefit asset, December 31	114,407	88,655
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income [Roll Forward]
AOCI debit/(credit), balance at beginning of the period (excluding impact of PUC D&Os)	(60,915)	(48,510)
Recognized during year – net actuarial gain (loss)	3,047	2,840
Occurring during year – net actuarial gain	(19,419)	(15,245)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(77,287)	(60,915)	(48,510)
Cumulative impact of PUC D&Os	71,355	55,140
AOCI debit/(credit), balance at end of the period	(5,932)	(5,775)
Net actuarial gain	(77,287)	(60,915)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(77,287)	(60,915)	$ (48,510)
Income taxes (benefits)	1,527	1,487
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	$ (4,405)	$ (4,288)