Retirement benefits - Components of Net Periodic Benefit Cost for Consolidated HEI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pension benefits
Defined Benefit Plan
Service cost	$ 11,265	$ 11,396	$ 22,529	$ 22,792
Interest cost	26,506	25,622	53,012	51,243
Expected return on plan assets	(35,982)	(35,197)	(71,964)	(70,392)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain)/losses	111	189	222	377
Net periodic pension/benefit cost (return)	1,900	2,010	3,799	4,020
Impact of PUC D&Os	18,089	18,133	36,179	36,266
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	19,989	20,143	39,978	40,286
Other benefits
Defined Benefit Plan
Service cost	282	343	563	687
Interest cost	1,867	2,157	3,734	4,314
Expected return on plan assets	(3,487)	(3,405)	(6,972)	(6,810)
Amortization of net prior period gain	0	(219)	0	(438)
Amortization of net actuarial (gain)/losses	(712)	(449)	(1,425)	(898)
Net periodic pension/benefit cost (return)	(2,050)	(1,573)	(4,100)	(3,145)
Impact of PUC D&Os	1,887	1,424	3,775	2,849
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	(163)	(149)	(325)	(296)
Hawaiian Electric Company, Inc. and Subsidiaries | Pension benefits
Defined Benefit Plan
Service cost	10,916	11,018	21,832	22,037
Interest cost	24,627	23,699	49,254	47,397
Expected return on plan assets	(33,775)	(32,971)	(67,552)	(65,943)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain)/losses	11	18	23	37
Net periodic pension/benefit cost (return)	1,779	1,764	3,557	3,528
Impact of PUC D&Os	18,089	18,133	36,179	36,266
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	19,868	19,897	39,736	39,794
Hawaiian Electric Company, Inc. and Subsidiaries | Other benefits
Defined Benefit Plan
Service cost	278	340	556	680
Interest cost	1,779	2,063	3,558	4,126
Expected return on plan assets	(3,434)	(3,354)	(6,868)	(6,707)
Amortization of net prior period gain	0	(218)	0	(436)
Amortization of net actuarial (gain)/losses	(694)	(433)	(1,388)	(867)
Net periodic pension/benefit cost (return)	(2,071)	(1,602)	(4,142)	(3,204)
Impact of PUC D&Os	1,887	1,424	3,775	2,849
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	$ (184)	$ (178)	$ (367)	$ (355)