Leases - (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)	Aug. 31, 2019 USD ($) ft²
Lessee, Lease, Description [Line Items]
Renewal option (up to)	10 years
Area of real estate property (in square feet) | ft²	64,000
Total present value of lease payments	$ 160,432	$ 199,571
Lessor, operating sublease, option to extend	2 years
Lessor, operating sublease, estimated base rent revenue	$ 8,300
Lease payments basis reduction for impact of collateral	0.25%
Operating lease cost	$ 74,520	73,584
Variable lease cost	229,938	205,172
Total lease cost	304,458	278,756
Cash paid for amounts included in the measurement of lease liabilities :
Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases	$ 71,584	$ 73,041
Weighted-average remaining lease term—operating leases (in years)	4 years 4 months 24 days	3 years 6 months
Weighted-average discount rate—operating leases	3.61%	3.96%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 74,000
2022	51,000
2023	8,000
2024	7,000
2025	5,000
Thereafter	27,000
Total lease payments	172,000
Less: Imputed interest	(12,000)
Total present value of lease payments	160,432	$ 199,571
Operating lease, not in service, annual capacity payment	$ 7,000
FHLB Des Moines | Maximum
Lessee, Lease, Description [Line Items]
Long-term debt term	30 years
Other Operating Leases
Lessee, Lease, Description [Line Items]
Total present value of lease payments	$ 59,000
Operating lease cost	11,201	10,265
Variable lease cost	12,765	13,034
Total lease cost	23,966	23,299
Cash paid for amounts included in the measurement of lease liabilities :
Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases	$ 10,783	$ 10,447
Weighted-average remaining lease term—operating leases (in years)	8 years 10 months 24 days	6 years 6 months
Weighted-average discount rate—operating leases	2.87%	3.50%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 11,000
2022	9,000
2023	8,000
2024	7,000
2025	5,000
Thereafter	27,000
Total lease payments	67,000
Less: Imputed interest	(8,000)
Total present value of lease payments	59,000
Power Purchase Agreements Qualifying As Operating Leases
Lessee, Lease, Description [Line Items]
Total present value of lease payments	101,000
Operating lease cost	63,319	$ 63,319
Variable lease cost	217,173	192,138
Total lease cost	280,492	255,457
Cash paid for amounts included in the measurement of lease liabilities :
Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases	$ 60,801	$ 62,594
Weighted-average remaining lease term—operating leases (in years)	1 year 9 months 18 days	2 years 9 months 18 days
Weighted-average discount rate—operating leases	4.08%	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 63,000
2022	42,000
2023	0
2024	0
2025	0
Thereafter	0
Total lease payments	105,000
Less: Imputed interest	(4,000)
Total present value of lease payments	101,000
Hawaiian Electric Company, Inc. and Subsidiaries
Lessee, Lease, Description [Line Items]
Total present value of lease payments	134,000
Operating lease cost	69,341	$ 68,274
Variable lease cost	227,015	202,410
Total lease cost	296,356	270,684
Cash paid for amounts included in the measurement of lease liabilities :
Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases	$ 67,024	$ 68,362
Weighted-average remaining lease term—operating leases (in years)	3 years 9 months 18 days	2 years 10 months 24 days
Weighted-average discount rate—operating leases	3.84%	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 69,000
2022	46,000
2023	4,000
2024	3,000
2025	3,000
Thereafter	19,000
Total lease payments	144,000
Less: Imputed interest	(10,000)
Total present value of lease payments	134,000
Hawaiian Electric Company, Inc. and Subsidiaries | Other Operating Leases
Lessee, Lease, Description [Line Items]
Total present value of lease payments	33,000
Operating lease cost	6,022	$ 4,955
Variable lease cost	9,842	10,272
Total lease cost	15,864	15,227
Cash paid for amounts included in the measurement of lease liabilities :
Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases	$ 6,223	$ 5,768
Weighted-average remaining lease term—operating leases (in years)	10 years 1 month 6 days	4 years 6 months
Weighted-average discount rate—operating leases	3.20%	4.11%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 6,000
2022	4,000
2023	4,000
2024	3,000
2025	3,000
Thereafter	19,000
Total lease payments	39,000
Less: Imputed interest	(6,000)
Total present value of lease payments	33,000
Hawaiian Electric Company, Inc. and Subsidiaries | Power Purchase Agreements Qualifying As Operating Leases
Lessee, Lease, Description [Line Items]
Total present value of lease payments	101,000
Operating lease cost	63,319	$ 63,319
Variable lease cost	217,173	192,138
Total lease cost	280,492	255,457
Cash paid for amounts included in the measurement of lease liabilities :
Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases	$ 60,801	$ 62,594
Weighted-average remaining lease term—operating leases (in years)	1 year 9 months 18 days	2 years 9 months 18 days
Weighted-average discount rate—operating leases	4.08%	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 63,000
2022	42,000
2023	0
2024	0
2025	0
Thereafter	0
Total lease payments	105,000
Less: Imputed interest	(4,000)
Total present value of lease payments	101,000
Honolulu
Lessee, Lease, Description [Line Items]
Area of real estate property (in square feet) | ft²			195,000
Operating lease term			12 years
Operating lease renewal term (up to)			10 years
Total present value of lease payments			$ 21,000
Lease not yet commenced expected reimbursements for improvements	$ 2,600	$ 0
Lessor, operating sublease, lease term	6 years 6 months
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Total present value of lease payments			21,000
Honolulu | Office Space Lease, Phase 1, Commencement January 2020
Lessee, Lease, Description [Line Items]
Lease not yet commenced, annual rent expense			1,900
Lease not yet commenced expected reimbursements for improvements			5,000
Honolulu | Office Space Lease, Phase 2, Commencement January 2021
Lessee, Lease, Description [Line Items]
Lease not yet commenced, annual rent expense			1,700
Lease not yet commenced liability			19,000
Lease not yet commenced expected reimbursements for improvements			$ 4,600