Bank segment (HEI only) - Mortgage Servicing Rights and Valuation Allowance Roll Forward (Details) - American Savings Bank (ASB) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Mortgage Servicing Rights [Roll Forward]
Beginning balance	$ 9,101
Ending balance	10,020	$ 9,101
Allowance for mortgage-servicing assets – bank
Mortgage Servicing Rights [Roll Forward]
Beginning balance	9,101	8,062	$ 8,639
Amount capitalized	5,096	2,987	1,045
Amortization	(3,917)	(1,948)	(1,622)
Sale of mortgage servicing rights	0	0	0
Other-than-temporary impairment	0	0	0
Ending balance	10,280	9,101	8,062
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance	0	0	0
Provision	260	0	0
Other-than-temporary impairment	0	0	0
Valuation allowance, ending balance	260	0	0
Net carrying amount	10,020	$ 9,101	$ 8,062
Estimated Aggregate Amortization Expenses of Mortgage Servicing Rights [Abstract]
2021	2,100
2022	1,700
2023	1,300
2024	1,000
2025	$ 800

Estimated Aggregate Amortization Expenses of Mortgage Servicing Rights [Abstract]

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Mortgage Servicing Rights [Roll Forward]

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Servicing Asset, Net

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Paragraph 2
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Amount of other-than-temporary impairment (OTTI) applied to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
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Amount of amortization of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount conveyed to unrelated parties of contract to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Reflects the estimated amount of impairment as of the balance sheet date of recognized servicing assets that are being amortized in proportion to and over the period of estimated net servicing income or loss.

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Amount of increase (decrease) in the valuation allowance for impairment of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer from expenses (recoveries) recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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