Leases (Details) ft² in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Aug. 31, 2019 USD ($) ft²	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Renewal option (up to)	10 years	10 years
Operating lease cost	$ 18,370	$ 55,066
Variable lease cost	61,489	152,954
Total lease cost	79,859	208,020
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	$ 19,482	$ 54,029
Weighted-average remaining lease term—operating leases (in years)	3 years 8 months 12 days	3 years 8 months 12 days
Weighted-average discount rate—operating leases	3.98%	3.98%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (remaining months)	$ 20,000	$ 20,000
2020	74,000	74,000
2021	72,000	72,000
2022	48,000	48,000
2023	4,000	4,000
2024	3,000	3,000
Thereafter	9,000	9,000
Total lease payments	230,000	230,000
Less: Imputed interest	(17,000)	(17,000)
Operating lease liabilities	213,166	213,166
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019				$ 74,000
2020				72,000
2021				71,000
2022				47,000
2023				4,000
Thereafter				12,000
Total lease payments				280,000
Other leases
Lessee, Lease, Description [Line Items]
Operating lease cost	2,892	8,632
Variable lease cost	3,577	9,777
Total lease cost	6,469	18,409
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	$ 2,687	$ 7,867
Weighted-average remaining lease term—operating leases (in years)	6 years 6 months	6 years 6 months
Weighted-average discount rate—operating leases	3.55%	3.55%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (remaining months)	$ 3,000	$ 3,000
2020	11,000	11,000
2021	9,000	9,000
2022	6,000	6,000
2023	4,000	4,000
2024	3,000	3,000
Thereafter	9,000	9,000
Total lease payments	45,000	45,000
Less: Imputed interest	(6,000)	(6,000)
Operating lease liabilities	39,000	39,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019				11,000
2020				9,000
2021				8,000
2022				5,000
2023				4,000
Thereafter				12,000
Total lease payments				49,000
PPAs classified as leases
Lessee, Lease, Description [Line Items]
Operating lease cost	15,478	46,434
Variable lease cost	57,912	143,177
Total lease cost	73,390	189,611
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	$ 16,795	$ 46,162
Weighted-average remaining lease term—operating leases (in years)	3 years	3 years
Weighted-average discount rate—operating leases	4.08%	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (remaining months)	$ 17,000	$ 17,000
2020	63,000	63,000
2021	63,000	63,000
2022	42,000	42,000
2023	0	0
2024	0	0
Thereafter	0	0
Total lease payments	185,000	185,000
Less: Imputed interest	(11,000)	(11,000)
Operating lease liabilities	$ 174,000	$ 174,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
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
Operating lease term			12 years
Operating lease renewal term (up to)			10 years
Annual rent expense, phase 1			$ 1,900
Annual rent expense, phase 2			$ 1,700
Hawaiian Electric Company, Inc. and Subsidiaries
Lessee, Lease, Description [Line Items]
Renewal option (up to)	10 years	10 years
Operating lease cost	$ 17,020	$ 50,985
Variable lease cost	60,748	150,863
Total lease cost	77,768	201,848
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	$ 18,250	$ 50,425
Weighted-average remaining lease term—operating leases (in years)	3 years 2 months 12 days	3 years 2 months 12 days
Weighted-average discount rate—operating leases	4.09%	4.09%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (remaining months)	$ 19,000	$ 19,000
2020	69,000	69,000
2021	68,000	68,000
2022	44,000	44,000
2023	2,000	2,000
2024	1,000	1,000
Thereafter	2,000	2,000
Total lease payments	205,000	205,000
Less: Imputed interest	(13,000)	(13,000)
Operating lease liabilities	192,000	192,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019				69,000
2020				69,000
2021				68,000
2022				44,000
2023				2,000
Thereafter				3,000
Total lease payments				255,000
Hawaiian Electric Company, Inc. and Subsidiaries | Other leases
Lessee, Lease, Description [Line Items]
Operating lease cost	1,542	4,551
Variable lease cost	2,836	7,686
Total lease cost	4,378	12,237
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	$ 1,455	$ 4,263
Weighted-average remaining lease term—operating leases (in years)	4 years 8 months 12 days	4 years 8 months 12 days
Weighted-average discount rate—operating leases	4.17%	4.17%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (remaining months)	$ 2,000	$ 2,000
2020	6,000	6,000
2021	5,000	5,000
2022	2,000	2,000
2023	2,000	2,000
2024	1,000	1,000
Thereafter	2,000	2,000
Total lease payments	20,000	20,000
Less: Imputed interest	(2,000)	(2,000)
Operating lease liabilities	18,000	18,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
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 | PPAs classified as leases
Lessee, Lease, Description [Line Items]
Operating lease cost	15,478	46,434
Variable lease cost	57,912	143,177
Total lease cost	73,390	189,611
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	$ 16,795	$ 46,162
Weighted-average remaining lease term—operating leases (in years)	3 years	3 years
Weighted-average discount rate—operating leases	4.08%	4.08%
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019 (remaining months)	$ 17,000	$ 17,000
2020	63,000	63,000
2021	63,000	63,000
2022	42,000	42,000
2023	0	0
2024	0	0
Thereafter	0	0
Total lease payments	185,000	185,000
Less: Imputed interest	(11,000)	(11,000)
Operating lease liabilities	$ 174,000	$ 174,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019				63,000
2020				63,000
2021				63,000
2022				42,000
2023				0
Thereafter				0
Total lease payments				$ 231,000