Bank segment (HEI only) - Capital And Ratio (Details) - American Savings Bank (ASB) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage, actual capital	$ 677,786	$ 641,547
Tier 1 leverage, actual ratio	0.0838	0.0906
Tier 1 leverage, required capital	$ 323,700	$ 283,122
Tier 1 leverage, required ratio	0.0400	0.0400
Tier 1 leverage, required to be well capitalized capital	$ 404,625	$ 353,903
Tier 1 leverage, required to be well capitalized ratio	0.0500	0.0500
Common equity tier 1, actual capital		$ 641,547
Common equity tier 1, actual ratio		13.18%
Common equity tier 1, required capital		$ 219,071
Common equity tier 1, required ratio		4.50%
Common equity tier 1, required to be well capitalized, Capital		$ 316,435
Common equity tier 1, required to be well capitalized, Ratio		6.50%
Tier 1 capital, actual capital		$ 641,547
Tier 1 capital, actual ratio		0.1318
Tier 1 capital, required capital		$ 292,094
Tier 1 capital, required ratio		0.0600
Tier 1 capital, Required to be well capitalized, Capital		$ 389,459
Tier 1 capital, Required to be well capitalized, Ratio		0.0800
Total capital, Actual capital		$ 696,643
Total capital, Actual ratio		0.1431
Total capital, Required capital		$ 389,459
Total capital, Required ratio		0.0800
Total capital, Required to be well capitalized, Capital		$ 486,823
Total capital, Required to be well capitalized, Ratio		0.1000

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