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, 2019	Dec. 31, 2018	Dec. 31, 2017
Mortgage Servicing Rights [Roll Forward]
Beginning balance	$ 8,062
Ending balance	9,101	$ 8,062
Allowance for mortgage-servicing assets – bank
Mortgage Servicing Rights [Roll Forward]
Beginning balance	8,062	8,639	$ 9,373
Amount capitalized	2,987	1,045	1,239
Amortization	(1,948)	(1,622)	(1,973)
Sale of mortgage servicing rights	0	0	0
Other-than-temporary impairment	0	0	0
Ending balance	9,101	8,062	8,639
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance	0	0	0
Provision (recovery)	0	0	0
Other-than-temporary impairment	0	0	0
Valuation allowance, ending balance	0	0	0
Net carrying amount	9,101	$ 8,062	$ 8,639
Estimated Aggregate Amortization Expenses of Mortgage Servicing Rights [Abstract]
2020	1,500
2021	1,200
2022	1,100
2023	900
2024	$ 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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Servicing Asset at Amortized Value, Amount Capitalized

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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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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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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