Electric utility segment - Power purchase agreements (Details) $ in Thousands		1 Months Ended					3 Months Ended		12 Months Ended
	Aug. 23, 2021	Jan. 31, 2022 USD ($)	Oct. 31, 2021	Jul. 31, 2018 MW	May 31, 2012 MW	Mar. 31, 1988 MW	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 1988 MW	Dec. 31, 2021 USD ($)
Regulatory Projects and Legal Obligations [Line Items]
Operating lease liabilities							$ 151,832			$ 136,760
Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchase commitment, extension period			10 years
Purchase commitment, price increase percentage							62.00%
AES Hawaii
Regulatory Projects and Legal Obligations [Line Items]
Purchase commitment, period (in years)						30 years
Minimum power volume required (in megawatts) | MW						180
Hu Honua Bioenergy, LLC
Regulatory Projects and Legal Obligations [Line Items]
Minimum power volume required (in megawatts) | MW					21.5
Molokai New Energy Partners
Regulatory Projects and Legal Obligations [Line Items]
Total contracted PV capacity (in megawatts) | MW				4.88
Total contracted battery energy storage system capacity | MW				3
Maximum power volume to be delivered (in megawatts) | MW				2.64
Sause Bros., Inc.
Regulatory Projects and Legal Obligations [Line Items]
Purchase commitment, period (in years)	5 years
Annual base rent		$ 6,200
Operating lease liabilities		$ 32,000
Hawaiian Electric, Parent
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							$ 164,000	$ 142,000
Hawaiian Electric, Parent | Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							60,000	37,000
Increased power purchase commitment capacity (in megawatts) | MW									208
Hawaiian Electric, Parent | AES Hawaii
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							27,000	30,000
Hawaiian Electric, Parent | HPOWER
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							19,000	17,000
Hawaiian Electric, Parent | Hamakua Energy
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							16,000	11,000
Hawaiian Electric, Parent | Puna Geothermal Venture
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							10,000	4,000
Hawaiian Electric, Parent | Wind IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							18,000	29,000
Hawaiian Electric, Parent | Solar IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							13,000	12,000
Hawaiian Electric, Parent | Other IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power							$ 1,000	$ 2,000