Leases - (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 31, 2020 USD ($)	Aug. 31, 2019 USD ($) ft²
Lessee, Lease, Description [Line Items]
Renewal option (up to)	10 years
Operating lease, liability	$ 199,571
Lease payments basis reduction for impact of collateral	0.15%
Operating lease cost	$ 73,584
Variable lease cost	205,172
Total lease cost	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	$ 73,041
Weighted-average remaining lease term—operating leases (in years)	3 years 6 months
Weighted-average discount rate—operating leases	3.96%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 75,000
2021	73,000
2022	48,000
2023	5,000
2024	4,000
Thereafter	9,000
Total lease payments	214,000
Less: Imputed interest	(14,000)
Total present value of lease payments1	$ 200,000
Future minimum lease payments
2019		$ 74,000
2020		72,000
2021		71,000
2022		47,000
2023		4,000
Thereafter		12,000
Total lease payments		280,000
Operating lease, rent expense		21,000	$ 20,000
FHLB Des Moines | Maximum
Lessee, Lease, Description [Line Items]
Long-term debt term	30 years
Other Operating Leases
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 10,265
Variable lease cost	13,034
Total lease cost	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	$ 10,447
Weighted-average remaining lease term—operating leases (in years)	6 years 6 months
Weighted-average discount rate—operating leases	3.50%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 12,000
2021	10,000
2022	6,000
2023	5,000
2024	4,000
Thereafter	9,000
Total lease payments	46,000
Less: Imputed interest	(5,000)
Total present value of lease payments1	41,000
Future minimum lease payments
2019		11,000
2020		9,000
2021		8,000
2022		5,000
2023		4,000
Thereafter		12,000
Total lease payments		49,000
Power Purchase Agreements Qualifying As Operating Leases
Lessee, Lease, Description [Line Items]
Operating lease cost	63,319
Variable lease cost	192,138
Total lease cost	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	$ 62,594
Weighted-average remaining lease term—operating leases (in years)	2 years 9 months 18 days
Weighted-average discount rate—operating leases	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 63,000
2021	63,000
2022	42,000
2023	0
2024	0
Thereafter	0
Total lease payments	168,000
Less: Imputed interest	(9,000)
Total present value of lease payments1	159,000
Future minimum lease payments
2019		63,000
2020		63,000
2021		63,000
2022		42,000
2023		0
Thereafter		0
Total lease payments		231,000
PGV Facility
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Operating lease, not in service, annual capacity payment	7,000
Hawaiian Electric Company, Inc. and Subsidiaries
Lessee, Lease, Description [Line Items]
Operating lease cost	68,274
Variable lease cost	202,410
Total lease cost	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	$ 68,362
Weighted-average remaining lease term—operating leases (in years)	2 years 10 months 24 days
Weighted-average discount rate—operating leases	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 70,000
2021	68,000
2022	45,000
2023	2,000
2024	1,000
Thereafter	2,000
Total lease payments	188,000
Less: Imputed interest	(11,000)
Total present value of lease payments1	177,000
Future minimum lease payments
2019		69,000
2020		69,000
2021		68,000
2022		44,000
2023		2,000
Thereafter		3,000
Total lease payments		255,000
Operating lease, rent expense		11,000	$ 11,000
Hawaiian Electric Company, Inc. and Subsidiaries | Other Operating Leases
Lessee, Lease, Description [Line Items]
Operating lease cost	4,955
Variable lease cost	10,272
Total lease cost	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	$ 5,768
Weighted-average remaining lease term—operating leases (in years)	4 years 6 months
Weighted-average discount rate—operating leases	4.11%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 7,000
2021	5,000
2022	3,000
2023	2,000
2024	1,000
Thereafter	2,000
Total lease payments	20,000
Less: Imputed interest	(2,000)
Total present value of lease payments1	18,000
Future minimum lease payments
2019		6,000
2020		6,000
2021		5,000
2022		2,000
2023		2,000
Thereafter		3,000
Total lease payments		24,000
Hawaiian Electric Company, Inc. and Subsidiaries | Power Purchase Agreements Qualifying As Operating Leases
Lessee, Lease, Description [Line Items]
Operating lease cost	63,319
Variable lease cost	192,138
Total lease cost	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	$ 62,594
Weighted-average remaining lease term—operating leases (in years)	2 years 9 months 18 days
Weighted-average discount rate—operating leases	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 63,000
2021	63,000
2022	42,000
2023	0
2024	0
Thereafter	0
Total lease payments	168,000
Less: Imputed interest	(9,000)
Total present value of lease payments1	$ 159,000
Future minimum lease payments
2019		63,000
2020		63,000
2021		63,000
2022		42,000
2023		0
Thereafter		0
Total lease payments		$ 231,000
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
Honolulu | Subsequent Event
Lessee, Lease, Description [Line Items]
Operating lease, liability				$ 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