Retirement benefits - Components of Net Periodic Benefit Cost for Consolidated HEI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension benefits
Defined Benefit Plan
Service cost	$ 11,396	$ 19,823	$ 22,792	$ 39,647
Interest cost	25,622	19,810	51,243	39,621
Expected return on plan assets	(35,197)	(35,331)	(70,392)	(70,664)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain) losses	189	6,297	377	12,594
Net periodic pension/benefit cost (return)	2,010	10,599	4,020	21,198
Impact of PUC D&Os	18,133	9,552	36,266	19,103
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	20,143	20,151	40,286	40,301
Other benefits
Defined Benefit Plan
Service cost	343	657	687	1,313
Interest cost	2,157	1,638	4,314	3,275
Expected return on plan assets	(3,405)	(3,398)	(6,810)	(6,795)
Amortization of net prior period gain	(219)	(232)	(438)	(464)
Amortization of net actuarial (gain) losses	(449)	(3)	(898)	(6)
Net periodic pension/benefit cost (return)	(1,573)	(1,338)	(3,145)	(2,677)
Impact of PUC D&Os	1,424	1,217	2,849	2,436
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	(149)	(121)	(296)	(241)
Hawaiian Electric Company, Inc. and Subsidiaries | Pension benefits
Defined Benefit Plan
Service cost	11,018	19,317	22,037	38,635
Interest cost	23,699	18,461	47,397	36,923
Expected return on plan assets	(32,971)	(33,545)	(65,943)	(67,091)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain) losses	18	6,125	37	12,250
Net periodic pension/benefit cost (return)	1,764	10,358	3,528	20,717
Impact of PUC D&Os	18,133	9,552	36,266	19,103
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	19,897	19,910	39,794	39,820
Hawaiian Electric Company, Inc. and Subsidiaries | Other benefits
Defined Benefit Plan
Service cost	340	649	680	1,298
Interest cost	2,063	1,572	4,126	3,145
Expected return on plan assets	(3,354)	(3,345)	(6,707)	(6,692)
Amortization of net prior period gain	(218)	(231)	(436)	(462)
Amortization of net actuarial (gain) losses	(433)	0	(867)	0
Net periodic pension/benefit cost (return)	(1,602)	(1,355)	(3,204)	(2,711)
Impact of PUC D&Os	1,424	1,217	2,849	2,436
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	$ (178)	$ (138)	$ (355)	$ (275)