Retirement benefits - 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, 2022	Dec. 31, 2021	Dec. 31, 2020
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 liability	$ (49,748)	$ (321,780)
Pension benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	2,644,639	2,624,530
Service cost	78,173	81,432	$ 73,387
Interest cost	80,062	75,361	81,335
Actuarial gains	(848,905)	(43,300)
Participants contributions	0	0
Benefits paid and expenses	(97,204)	(93,384)
Benefit obligation, balance at the end of the period	1,856,765	2,644,639	2,624,530
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	2,320,745	2,089,491
Actual return on plan assets	(461,669)	271,443
Employer contributions	42,542	51,777
Participants contributions	0	0
Benefits paid and expenses	(95,239)	(91,966)
Fair value of plan assets, balance at the end of the period	1,806,379	2,320,745	2,089,491
Accrued benefit asset (liability), balance	(50,386)	(323,894)
Other assets	21,012	23,675
Defined benefit pension and other postretirement benefit plans liability	(71,398)	(347,569)
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)	347,799	557,564
Recognized during year – prior service credit	0	0
Recognized during year – net actuarial gain (loss)	(27,412)	(27,245)
Occurring during year – net actuarial gain	(245,969)	(182,520)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	74,418	347,799	557,564
Cumulative impact of PUC D&Os	(55,201)	(324,162)
AOCI debit/(credit), balance at end of the period	19,217	23,637
Net actuarial loss (gain)	74,418	347,799
Prior service gain	0	0
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	74,418	347,799	557,564
Income taxes (benefits)	(5,088)	(6,199)
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	14,129	17,438
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	2,464,944	2,440,758
Service cost	75,845	79,463	71,604
Interest cost	74,363	70,235	75,484
Actuarial gains	(804,498)	(39,755)
Participants contributions	0	0
Benefits paid and expenses	(88,450)	(85,425)
Transfers	(6,079)	(332)
Benefit obligation, balance at the end of the period	1,716,125	2,464,944	2,440,758
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	2,142,617	1,909,730
Actual return on plan assets	(426,825)	266,922
Employer contributions	41,894	51,079
Participants contributions	0	0
Benefits paid and expenses	(87,952)	(84,852)
Other	(3,854)	(262)
Fair value of plan assets, balance at the end of the period	1,665,880	2,142,617	1,909,730
Accrued benefit asset (liability), balance	(50,245)	(322,327)
Other assets	0	0
Other liabilities (short-term)	(497)	(547)
Defined benefit pension and other postretirement benefit plans liability	(49,748)	(321,780)
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)	329,645	538,521
Recognized during year – prior service credit	0	0
Recognized during year – net actuarial gain (loss)	(26,358)	(27,534)
Occurring during year – net actuarial gain	(246,023)	(181,342)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	57,264	329,645	538,521
Cumulative impact of PUC D&Os	(55,201)	(324,162)
AOCI debit/(credit), balance at end of the period	2,063	5,483
Net actuarial loss (gain)	57,264	329,645
Prior service gain	0	0
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	57,264	329,645	538,521
Income taxes (benefits)	(531)	(1,412)
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	1,532	4,071
Other benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, balance at the beginning of the period	218,151	226,421
Service cost	2,580	2,827	2,537
Interest cost	6,502	6,122	7,407
Actuarial gains	(60,283)	(8,527)
Participants contributions	3,348	2,943
Benefits paid and expenses	(12,862)	(11,635)
Benefit obligation, balance at the end of the period	157,436	218,151	226,421
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	239,311	219,873
Actual return on plan assets	(39,469)	28,130
Employer contributions	0	0
Participants contributions	3,348	2,943
Benefits paid and expenses	(12,643)	(11,635)
Fair value of plan assets, balance at the end of the period	190,547	239,311	219,873
Accrued benefit asset (liability), balance	33,111	21,160
Other assets	33,526	21,663
Defined benefit pension and other postretirement benefit plans liability	(415)	(503)
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)	(19,975)	2,395
Recognized during year – prior service credit	928	1,533
Recognized during year – net actuarial gain (loss)	12	(203)
Occurring during year – net actuarial gain	(7,203)	(23,700)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(26,238)	(19,975)	2,395
Cumulative impact of PUC D&Os	19,486	19,166
AOCI debit/(credit), balance at end of the period	(6,752)	(809)
Net actuarial loss (gain)	(25,363)	(18,172)
Prior service gain	(875)	(1,803)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(26,238)	(19,975)	2,395
Income taxes (benefits)	1,740	209
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	(5,012)	(600)
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	209,470	217,074
Service cost	2,554	2,802	2,515
Interest cost	6,227	5,875	7,103
Actuarial gains	(58,253)	(7,779)
Participants contributions	3,286	2,886
Benefits paid and expenses	(12,750)	(11,388)
Transfers	0	0
Benefit obligation, balance at the end of the period	150,534	209,470	217,074
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, balance at the beginning of the period	235,525	216,315
Actual return on plan assets	(38,764)	27,712
Employer contributions	0	0
Participants contributions	3,286	2,886
Benefits paid and expenses	(12,541)	(11,388)
Other	(12)	0
Fair value of plan assets, balance at the end of the period	187,494	235,525	216,315
Accrued benefit asset (liability), balance	36,960	26,055
Other assets	36,960	26,055
Other liabilities (short-term)	0	0
Defined benefit pension and other postretirement benefit plans liability	0	0
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)	(20,231)	1,181
Recognized during year – prior service credit	925	1,530
Recognized during year – net actuarial gain (loss)	0	(206)
Occurring during year – net actuarial gain	(6,096)	(22,736)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(25,402)	(20,231)	1,181
Cumulative impact of PUC D&Os	19,486	19,166
AOCI debit/(credit), balance at end of the period	(5,916)	(1,065)
Net actuarial loss (gain)	(24,530)	(18,434)
Prior service gain	(872)	(1,797)
AOCI debit/(credit), balance at end of the period (excluding impact of PUC D&Os)	(25,402)	(20,231)	$ 1,181
Income taxes (benefits)	1,523	274
AOCI debit/(credit), net of taxes (benefits) balance at the end of the period	$ (4,393)	$ (791)