XML 94 R40.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Summary of significant accounting policies (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2021
Accounting Policies [Abstract] |
Summary of amounts in income tax expense related to investments in qualifying affordable housing projects | The table below summarizes the amounts in income tax expense related to ASB’s LIHTC investments:
Years ended December 31 | 2021 |  | 2020 |  | 2019
(in millions) |  |  |  |  |
Amounts in income taxes related to low-income housing tax credit investments |  |  |  |  |
Amortization recognized in the provision for income taxes | $ | (10.3) |  |  | $ | (9.6) |  |  | $ | (7.9) |
Tax credits and other tax benefits recognized in the provision for income taxes | 13.9 |  |  | 13.7 |  |  | 11.9 |
Net benefit to income tax expense | $ | 3.6 |  |  | $ | 4.1 |  |  | $ | 4.0 |

X
- Definition Summary Of Amounts In Income Tax Expense, Affordable Housing Projects [Table Text Block] + References No definition available. + Details
Name: | he_SummaryOfAmountsInIncomeTaxExpenseAffordableHousingProjectsTableTextBlock
Namespace Prefix: | he_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration