Retirement benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Defined Benefit Plan
Contributions made to defined benefit plans			$ 21,000	$ 23,000
Contributions expected to be paid in current year	$ 41,000		41,000		$ 52,000
Expected payments for remainder of fiscal year	3,000		3,000		1,000
Retirement benefits expense			$ 24,000	23,000
Number of years for which regulatory asset/liability for each utility will be amortized, beginning with respective utility's next rate case (in years)			5 years
Defined contribution plan, expenses recognized			$ 4,100	3,200
Cash contributions by the employer to defined contribution plan			$ 3,500	3,200
Employer contribution, percent of employee annual compensation			10.00%
Pension benefits
Defined Benefit Plan
Service cost	19,823	$ 20,465	$ 39,647	40,929
Interest cost	19,810	18,800	39,621	37,601
Expected return on plan assets	(35,331)	(33,068)	(70,664)	(66,135)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain) losses	6,297	8,431	12,594	9,987
Net periodic pension/benefit cost (return)	10,599	14,628	21,198	22,382
Impact of PUC D&Os	9,552	5,513	19,103	16,680
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	20,151	20,141	40,301	39,062
Other benefits
Defined Benefit Plan
Service cost	657	705	1,313	1,410
Interest cost	1,638	1,569	3,275	3,138
Expected return on plan assets	(3,398)	(3,232)	(6,795)	(6,465)
Amortization of net prior period gain	(232)	(384)	(464)	(767)
Amortization of net actuarial (gain) losses	(3)	44	(6)	298
Net periodic pension/benefit cost (return)	(1,338)	(1,298)	(2,677)	(2,386)
Impact of PUC D&Os	1,217	1,176	2,436	2,146
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	(121)	(122)	(241)	(240)
Hawaiian Electric Company, Inc. and Subsidiaries
Defined Benefit Plan
Contributions made to defined benefit plans			20,000	23,000
Contributions expected to be paid in current year	41,000		41,000		51,000
Expected payments for remainder of fiscal year	1,000		1,000		$ 1,000
Retirement benefits expense			23,000	23,000
Defined contribution plan, expenses recognized			1,800	1,500
Cash contributions by the employer to defined contribution plan			1,800	1,500
Hawaiian Electric Company, Inc. and Subsidiaries | Pension benefits
Defined Benefit Plan
Service cost	19,317	19,993	38,635	39,987
Interest cost	18,461	17,531	36,923	35,062
Expected return on plan assets	(33,545)	(31,367)	(67,091)	(62,735)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain) losses	6,125	8,212	12,250	10,771
Net periodic pension/benefit cost (return)	10,358	14,369	20,717	23,085
Impact of PUC D&Os	9,552	5,513	19,103	16,680
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	19,910	19,882	39,820	39,765
Hawaiian Electric Company, Inc. and Subsidiaries | Other benefits
Defined Benefit Plan
Service cost	649	698	1,298	1,397
Interest cost	1,572	1,504	3,145	3,008
Expected return on plan assets	(3,345)	(3,182)	(6,692)	(6,364)
Amortization of net prior period gain	(231)	(382)	(462)	(765)
Amortization of net actuarial (gain) losses	0	43	0	293
Net periodic pension/benefit cost (return)	(1,355)	(1,319)	(2,711)	(2,431)
Impact of PUC D&Os	1,217	1,176	2,436	2,146
Net periodic pension/benefit cost (adjusted for impact of PUC D&Os)	$ (138)	$ (143)	$ (275)	$ (285)