Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Hawaiian Electric Industries, Inc. Parent Company [Member] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Assets Assets [Abstract] Cash and cash equivalents Cash, Cash Equivalents, and Federal Funds Sold Accounts receivable Accounts Receivable, Net Property, plant and equipment, net Property, Plant and Equipment, Net Deferred income tax assets Deferred Income Tax Assets, Net Other assets Other Assets Investments in subsidiaries, at equity Investment in Subsidiaries The entity's equity interest in its subsidiaries. Total assets Assets LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity [Abstract] Liabilities Liabilities [Abstract] Accounts payable Accounts Payable Interest payable Interest Payable Notes payable to subsidiaries Notes Payable to Subsidiaries The carrying value as of the balance sheet date of notes payable to subsidiaries. Commercial paper Commercial Paper Short-term borrowings from non-affiliate Short-term Debt Long-term debt, net Long-term Debt Retirement benefits liability Postemployment Benefits Liability Other Other Liabilities Total liabilities Liabilities Shareholders' equity Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, no par value, authorized 10,000,000 shares; issued: none Preferred Stock, Value, Issued Common stock equity Common Stocks, Including Additional Paid in Capital, Net of Discount Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders’ equity Stockholders' Equity Attributable to Parent Total capitalization and liabilities Liabilities and Equity Preferred stock, authorized shares Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Common stock, authorized shares Common Stock, Shares Authorized Common stock, issued shares Common Stock, Shares, Issued Common stock, outstanding shares Common Stock, Shares, Outstanding Income Statement [Abstract] Statement [Table] Statement [Table] Hawaiian Electric Company, Inc. and Subsidiaries Hawaiian Electric Company and Subsidiaries [Member] Represents Hawaiian Electric Company, Inc, and Subsidiaries. Statement [Line Items] Statement [Line Items] Revenues Revenues Expenses Utilities Operating Expense [Abstract] Fuel oil Utilities Operating Expense, Fuel Used Purchased power Utilities Operating Expense, Purchased Power Other operation and maintenance Utilities Operating Expense, Maintenance and Operations Depreciation Utilities Operating Expense, Depreciation and Amortization Taxes, other than income taxes Utilities Operating Expense Other Taxes Discloses the amount of operating expense for the period related to taxes other than income taxes. Total expenses Costs and Expenses Operating income Operating Income (Loss) Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Interest expense and other charges, net Interest Expense and Other Charges Interest expense and other charges during the period. Allowance for borrowed funds used during construction Interest Costs Capitalized Adjustment Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income taxes Income Tax Expense (Benefit) Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Preferred stock dividends of subsidiaries Noncontrolling Interest in Net Income (Loss) Preferred Unit Holders, Redeemable Net income attributable to Hawaiian Electric Net Income (Loss) Attributable to Parent Preferred stock dividends of Hawaiian Electric Preferred Stock Dividends, Income Statement Impact Net income for common stock Net Income (Loss) Available to Common Stockholders, Basic Statement of Financial Position [Abstract] Property, plant and equipment, net Property, Plant and Equipment, Net [Abstract] Land Public Utilities, Property, Plant and Equipment, Land Plant and equipment Public Utilities Property Plant and Equipment Transmission Distribution Generation and Other Period end amount of property, plant and equipment (PPE) related to transmission, distribution, generation and other owned by public utility. Less accumulated depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Construction in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Utility property, plant and equipment, net Public Utilities, Property, Plant and Equipment, Net Nonutility property, plant and equipment, less accumulated depreciation of $1,251 as of December 31, 2017 and $1,232 as of December 31, 2016 Non-utilities, Property, Plant and Equipment, Net Non-utilities, Property, Plant and Equipment, Net Total property, plant and equipment, net Current assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Customer accounts receivable, net Accounts Receivable, Net, Current Accrued unbilled revenues, net Unbilled Receivables, Current Other accounts receivable, net Accounts and Other Receivables, Net, Current Fuel oil stock, at average cost Energy Related Inventory Materials and supplies, at average cost Inventory, Raw Materials and Supplies, Gross Prepayments and other Prepaid Expense and Other Assets, Current Regulatory assets Regulatory Assets, Current Total current assets Assets, Current Regulatory assets Regulatory Assets, Noncurrent Unamortized debt expense Unamortized Debt Issuance Expense Other Other Assets, Noncurrent Total other long-term assets Assets Noncurrent Excluding Property, Plant and Equipment, Net The carrying value of assets which are intended to be held for a period exceeding one year, excluding property, plant and equipment. Capitalization and liabilities Common stock equity Cumulative preferred stock – not subject to mandatory redemption Commitments and contingencies Commitments and Contingencies Long-term debt, net Long-term Debt, Excluding Current Maturities Total capitalization Capitalization, Long-term Debt and Equity Current liabilities Liabilities, Current [Abstract] Current portion of long-term debt Long-term Debt, Current Maturities Accounts payable Accounts Payable, Current Interest and dividends payable Interest and Dividends Payable Including Dividends on Preferred Stock of Subsidiaries Sum of the carrying values as of the balance sheet date of (a) interest payable on all forms of debt, including trade payables, that has been incurred, and (b) dividends declared but unpaid on equity securities issued by the entity and outstanding (also includes dividends collected on behalf of another owner of securities that are being held by the entity). This includes dividends on preferred stock of subsidiaries. Taxes accrued, including revenue taxes Taxes Payable, Current Regulatory liabilities Regulatory Liability, Current Other Other Liabilities, Current Total current liabilities Liabilities, Current Deferred credits and other liabilities Liabilities, Noncurrent [Abstract] Deferred income taxes Deferred Income Tax Liabilities, Net Regulatory liabilities Regulatory Liability, Noncurrent Unamortized tax credits Accumulated Deferred Investment Tax Credit Defined benefit pension and other postretirement benefit plans liability Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Other Other Liabilities, Noncurrent Total deferred credits and other liabilities Liabilities, Other than Long-term Debt, Noncurrent Contributions in aid of construction Contributions in Aid of Construction Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Award Type [Domain] Equity Award [Domain] Common stock Common Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Shares granted Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Fair value of vested stock Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Income tax benefit Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Revenues Revenues [Abstract] Revenues Sales Revenue and Interest and Dividends, Net Total revenue from sale of goods and services, including interest and dividends, rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. Equity in net income of subsidiaries Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Expenses: Costs and Expenses [Abstract] Operating, administrative and general Operating Expenses Depreciation of property, plant and equipment Depreciation Taxes, other than income taxes Taxes, Other than Income All taxes not related to income of the entity and that are not reported elsewhere. Income before merger termination fee, interest expense and income (taxes) benefits Net Income (Loss), Before Merger Termination Fee, Interest Expense And Income (Tax) Benefit Net Income (Loss), Before Merger Termination Fee, Interest Expense And Income (Tax) Benefit Merger termination fee Merger Termination Fee Merger Termination Fee Income before interest expense and income (taxes) benefits Net Income (Loss), Before Interest Expense And Income (Tax) Benefit Net Income (Loss), Before Interest Expense And Income (Tax) Benefit Interest expense, net Interest Expense Income (taxes) benefits Regulatory Capital Requirements [Abstract] Schedule of Restricted Regulatory Assets [Table] Schedule of Restricted Regulatory Assets [Table] Represents the table of regulatory assets which are restricted to transfer without Public Utilities Commission approval. American Savings Bank (ASB) American Savings Bank FSB [Member] American Savings Bank FSB Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] ASB Hawaii, Inc. ASB Hawaii, Inc. [Member] ASB Hawaii, Inc. [Member] Regulatory restrictions on net assets Schedule of Restricted Regulatory Assets [Line Items] -- None. No documentation exists for this element. -- Restrictions on transfer of net assets to the parent in the form of cash dividends, loans and advances Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries Bank Segment Disclosure [Abstract] Bank Segment Disclosure [Abstract] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Portfolio Segment [Axis] Class of Financing Receivable, Type [Axis] Financing Receivable Allowance [Domain] Class of Financing Receivable, Type [Domain] Residential 1-4 family Residential 1 to 4 Family Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to residential 1-4 family financing receivables. Commercial real estate Commercial Real Estate Portfolio Segment [Member] Home equity line of credit Home Equity Line of Credit [Member] Residential land Residential Land Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to residential land receivables. Commercial construction Construction Loans [Member] Residential construction Residential Construction Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to residential construction. Commercial Commercial Loan [Member] Consumer Consumer Loan [Member] Unallocated Unallocated Financing Receivables [Member] Allowance for loan losses Financing Receivable, Allowance for Credit Losses [Line Items] Allowance for loan losses: Financing Receivable, Allowance for Credit Losses [Roll Forward] Valuation allowance, balance at the beginning of the period Financing Receivable, Allowance for Credit Losses Charge-offs Financing Receivable, Allowance for Credit Losses, Write-downs Recoveries Financing Receivable, Allowance for Credit Losses, Recovery Provision Provision for Loan, Lease, and Other Losses Valuation allowance, balance at the end of the period Ending balance: individually evaluated for impairment Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Ending balance: collectively evaluated for impairment Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Financing Receivables: Financing Receivable, Net [Abstract] Total financing receivables Financing Receivable, Net Ending balance: individually evaluated for impairment Financing Receivable, Individually Evaluated for Impairment Ending balance: collectively evaluated for impairment Financing Receivable, Collectively Evaluated for Impairment Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] Credit risk profile based on nonaccrual loans Financing Receivable, Recorded Investment, Past Due [Line Items] Nonaccrual loans Financing Receivable, Recorded Investment, Nonaccrual Status Accruing loans 90 days or more past due Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Troubled debt restructured loans not included above Financing Receivable, Modifications, Post-Modification Recorded Investment Advances from Federal Home Loan Bank Advances from Federal Home Loan Banks [Abstract] Weighted-average stated rate Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due [Abstract] 2018 Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due within One Year of Balance Sheet Date 2019 Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, One to Two Years from Balance Sheet Date 2020 Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, Two to Three Years from Balance Sheet Date 2021 Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, Three to Four Years from Balance Sheet Date 2022 Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, Four to Five Years from Balance Sheet Date Thereafter Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, after Five Years from Balance Sheet Date Total weighted-average stated rate Federal Home Loan Bank, Advances Maturities Summary, Average Interest Rate The total of weighted average interest rate applicable to the Federal Home Loan Bank advances. Due in Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract] 2018 Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months 2019 Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Two 2020 Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Three 2021 Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Four 2022 Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Five Thereafter Federal Home Loan Bank, Advances, Maturities Summary, Due after Year Five Total amount due Advances from Federal Home Loan Banks Risks and Uncertainties [Abstract] Percentage of benchmark loan to appraisal ratio in excess of which mortgage insurance is required Minimum Benchmark Percentage of Loan to Appraisal Ratio which Mortgage Insurance is Required Represents the minimum benchmark percentage of loan to appraisal ratio which mortgage insurance is required as per the policy of the reporting entity. Supplemental Cash Flow Elements [Abstract] Schedule of supplemental disclosures of cash and noncash activity Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Electric utility subsidiary -- None. No documentation exists for this element. -- Regulatory Projects and Legal Obligations [Table] Regulatory Projects and Legal Obligations [Table] Discloses the components of regulatory projects and legal obligations. Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Hawaiian Electric Company, Inc (HECO) Subsidiaries [Member] Hamakua Energy Partners, L.P. (HEP) Hamakua Energy Partners L P [Member] Represents an independent power producer (IPP) with whom the entity has entered into a power purchase agreement. HELCO Hawaii Electric Light Company, Inc [Member] Hawaii Electric Light Company, Inc [Member] MECO Maui Electric Company Limited [Member] Maui Electric Company Limited [Member] Maui Electric Company, Limited (MECO) Subsidiaries Three [Member] This element represents Maui Electric Company, Limited, an electric utility subsidiary of Hawaiian Electric Company, Inc. Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Chevron Chevron Products Company [Member] Chevron Products Company [Member] Pacific Biodiesel Technologies Pacific Biodiesel Technologies, LLC [Member] Pacific Biodiesel Technologies, LLC [Member] REG Marketing & Logistics REG Marketing & Logistics, LLC [Member] REG Marketing & Logistics, LLC [Member] Kalaeloa Partners, L.P. (Kalaeloa) Kalaeloa Partners L P [Member] Represents an independent power producer (IPP) with whom the entity has entered into a power purchase agreement. AES Hawaii, Inc. (AES Hawaii) AES Hawaiian Inc [Member] Represents an independent power producer (IPP) with whom the entity has entered into a power purchase agreement. Hu Honua Bioenergy Hu Honua Bioenergy, LLC [Member] Hu Honua Bioenergy, LLC [Member] Hawaiian Telcom Hawaiian Telcom [Member] Hawaiian Telcom [Member] Category of Item Purchased [Axis] Category of Item Purchased [Axis] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment, Category of Item Purchased [Domain] Biodiesel Fuel Biodiesel Fuel [Member] Biodiesel Fuel [Member] Major Vendor [Axis] Major Vendor [Axis] Vendor that is considered major by the entity. Major Vendor [Domain] Major Vendor [Domain] Name and description of the vendor that account for major purchases of the entity. Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Domain] Environmental Remediation Contingency [Domain] PCB Contamination PCB Contamination [Member] PCB Contamination [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Regulatory Projects and Legal Obligations [Line Items] Regulatory Projects and Legal Obligations [Line Items] -- None. No documentation exists for this element. -- Fuel contracts Fuel Supply Contracts [Abstract] -- None. No documentation exists for this element. -- Estimated cost of minimum purchase within 2018 year Long Term Purchase Commitment Amount within One Year The minimum estimated amount in the first year after the balance sheet date the entity agreed to spend under the long-term purchase commitment. Estimated cost of minimum purchase in 2019 year Long Term Purchase Commitment Amount in Second Year The minimum estimated amount in the second year after the balance sheet date the entity agreed to spend under the long-term purchase commitment. Cost of purchases Cost of Purchases Represents the actual cost of purchases. Power purchase agreements Power Purchase Agreements [Abstract] -- None. No documentation exists for this element. -- Number of power purchase agreements (PPAs) Number of Power Purchase Agreements Represents the number of firm power purchase agreements entered into, by the company. Power purchase agreement, extension period (in years) Long-term Purchase Commitment, Extension Period Long-term Purchase Commitment, Extension Period Revenue subject to refund Public Utility, Revenue Subject To Refund Public Utility, Revenue Subject To Refund Power purchase capacity excluding agreements with smaller IPPs (in megawatts) Aggregate of Power Purchase Capacity Excluding Agreement with Smaller Independent Power Producers Represents the entity's aggregate capacity utilized under power purchase agreements (PPAs) excluding power purchase agreements with smaller independent power producers and schedule Q providers. Expected fixed capacity charges per year for 2018 through 2022, minimum Utilities Minimum Expected Fixed Capacity Charges Per Year, One Through Five Years Represents the minimum amount of expected fixed capacity charges per year for years one through five. Expected fixed capacity charges from 2023 through 2033 Utilities Expected Fixed Capacity Charges, After Five Through Fifteen Years Utilities Expected Fixed Capacity Charges, After Five Through Fifteen Years Power purchase capacity (in megawatts) Aggregate of Power Purchase Capacity Represents the entity's aggregate capacity utilized under power purchase agreements (PPAs). Number of years entity entered under power purchase agreement Number of Years Entity Entered under Power Purchase Agreement Represents the number of years under which the entity has entered for power purchase agreement. Power purchase capacity that Increases from initial capacity (in megawatts) Aggregate of Power Purchase Capacity Increases from Initial Capacity Aggregate of Power Purchase Capacity Increases from Initial Capacity Power purchase agreement, termination period Power Purchase Agreement, Termination Period Power Purchase Agreement, Termination Period Purchase commitment, period Long-term Purchase Commitment, Period Purchase commitment, minimum power volume required to be purchased Long-term Purchase Commitment, Minimum Power Volume Required Long-term Purchase Commitment, Minimum Power Volume Required Purchase commitment, arbitration, additional capacity requirement Long Term Purchase Commitment, Arbitration, Additional Capacity Requirement Long Term Purchase Commitment, Arbitration, Additional Capacity Requirement Renewable projects Renewable Projects [Abstract] Renewable Projects [Abstract] ERP/EAM implementation project costs Public Utilities, ERP/EAM Implementation Project Costs Public Utilities, ERP/EAM Implementation Project Costs ERP/EAM cost recovery cap Public Utility, ERP/EAM Cost Recovery Cap Public Utility, ERP/EAM Cost Recovery Cap ERP/EAM required pass-through savings Public Utility, ERP/EAM Required Pass-through Savings Public Utility, ERP/EAM Required Pass-through Savings ERP/EAM project service period (in years) Public Utility, ERP/EAM Project Service Period Public Utility, ERP/EAM Project Service Period Weighted average AFUDC rate Public Utilities, Allowance for Funds Used During Construction, Rate ERP/EAM estimated total benefits Public Utility, ERP/EAM Estimated Total Benefits Public Utility, ERP/EAM Estimated Total Benefits ERP/EAM implementation project costs, operations and management Public Utilities, ERP/EAM Implementation Project Costs, Operations And Management Public Utilities, ERP/EAM Implementation Project Costs, Operations And Management ERP/EAM implementation project costs, capital costs Public Utilities, ERP/EAM Implementation Project Costs, Capital Costs Public Utilities, ERP/EAM Implementation Project Costs, Capital Costs ERP/EAM implementation project costs, deferred costs Public Utilities, ERP/EAM Implementation Project Costs, Deferred Costs Public Utilities, ERP/EAM Implementation Project Costs, Deferred Costs Project facility capacity (in mW) Public Utility, Project Facility Capacity Public Utility, Project Facility Capacity Maximum project budget Public Utility, Maximum Project Budget Public Utility, Maximum Project Budget Percent of costs recoverable through recovery mechanisms other than base rates Public Utility, Project, Percent Of Cost Recoverable Through Recovery Mechanisms Other Than Base Rates Public Utility, Project, Percent Of Cost Recoverable Through Recovery Mechanisms Other Than Base Rates Decrease In project costs Public Utility, Decrease In Project Costs Public Utility, Decrease In Project Costs Project, lease term (in years) Public Utility, Project, Lease Term Public Utility, Project, Lease Term Total project costs incurred Public Utility, Project, Total Project Cost Incurred Public Utility, Project, Total Project Cost Incurred Environmental regulation Environmental Remediation Obligations [Abstract] Solar project, energy production (in megawatts) Public Utilities, Solar Project, Facility Energy Production Public Utilities, Solar Project, Facility Energy Production Solar project, project cap Public Utilities, Solar Project, Project Cap Public Utilities, Solar Project, Project Cap Solar project, maximum energy costs (in dollars per KWH) Public Utilities, Solar Project, Maximum Energy Cost Public Utilities, Solar Project, Maximum Energy Cost Solar project, cost incurred Public Utilities, Solar Project, Cost Incurred Public Utilities, Solar Project, Cost Incurred Accounts receivable and unbilled revenues, net Allowance for doubtful accounts receivable Allowance for Doubtful Accounts Receivable Additional accrued investigation and estimated cleanup costs Reserve for Additional Investigation and Estimated Clean up Costs Represents the amount of additional accrued investigation and estimated cleanup costs. Accrual for environmental loss contingencies Accrual for Environmental Loss Contingencies ARO, recognition impact on earnings Asset Retirement Obligations, Recognition Impact on Earnings Represents the amount of impact on earnings from recognition of asset retirement obligations (AROs). Changes in the asset retirement obligation liability Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Balance at the beginning of the period Asset Retirement Obligation Accretion expense Asset Retirement Obligation, Accretion Expense Liabilities incurred Asset Retirement Obligation, Liabilities Incurred Liabilities settled Asset Retirement Obligation, Liabilities Settled Revisions in estimated cash flows Asset Retirement Obligation, Revision of Estimate Balance at the end of the period Decoupling Decoupling [Abstract] Decoupling [Abstract] Decoupling, revision in estimated cash flows Settlement Agreement Expiration, Revenue Adjustment, Before Taxes Settlement Agreement Expiration, Revenue Adjustment, Before Taxes Target performance historical measurement period Public Utility, Decoupling Order, Performance Incentive Mechanism, Service Reliability, Target Performance Historical Measurement Period Public Utility, Decoupling Order, Performance Incentive Mechanism, Service Reliability, Target Performance Historical Measurement Period Service reliability, maximum penalty, percent of return on equity Public Utility, Decoupling Order, Performance Incentive Mechanism, Service Reliability, Maximum Penalty, Percent Of Return On Equity Public Utility, Decoupling Order, Performance Incentive Mechanism, Service Reliability, Maximum Penalty, Percent Of Return On Equity Maximum penalty amount Public Utility, Decoupling Order, Performance Incentive Mechanism, Service Reliability, Maximum Penalty, Amount Public Utility, Decoupling Order, Performance Incentive Mechanism, Service Reliability, Maximum Penalty, Amount Dead band percentage above or below target Public Utility, Decoupling Order, Performance Incentive Mechanism, Call Center Performance, Dead Band Percentage Above Or Below Target Public Utility, Decoupling Order, Performance Incentive Mechanism, Call Center Performance, Dead Band Percentage Above Or Below Target Call center performance, maximum penalty amount Public Utility, Decoupling Order, Call Center Performance, Maximum Penalty, Amount Public Utility, Decoupling Order, Call Center Performance, Maximum Penalty, Amount Threshold of capital expenditures in excess of customer contributions for qualification for major project interim recovery Public Utility, Decoupling Order, Threshold Of Capital Expenditures In Excess Of Customer Contributions For Qualification For Major Project Interim Recovery Public Utility, Decoupling Order, Threshold Of Capital Expenditures In Excess Of Customer Contributions For Qualification For Major Project Interim Recovery General rate increase, revenue Public Utilities, General Rate Increase, Revenue Public Utilities, General Rate Increase, Revenue Revenue, calculation assumption, rate of return Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return Revenue, calculation assumptions, rate of return, return on average common equity Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity Decoupling order, requirement for application for general rate case Public Utilities, Decoupling Order, Requirement For Application For General Rate Case Public Utilities, Decoupling Order, Requirement For Application For General Rate Case Stipulated settlement letter, basis spread on reduction amount Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity, Basis Spread On Reduction Amount Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity, Basis Spread On Reduction Amount Stipulated settlement letter, perent of pass-through of minor energy generation fuel recovery Public Utilities, General Rate Increase, Agreement Revision, Percent Of Pass Through Of Minor Energy Generation Fuel Recovery Public Utilities, General Rate Increase, Agreement Revision, Percent Of Pass Through Of Minor Energy Generation Fuel Recovery Statement of probable entitlement, interim increase Public Utilities, Statement Of Probable Entitlement, Interim Increase Public Utilities, Statement Of Probable Entitlement, Interim Increase Statement of probable entitlement, calculation assumptions, rate of return Public Utilities, Statement Of Probable Entitlement, Revenue, Calculation Assumptions, Rate Of Return Public Utilities, Statement Of Probable Entitlement, Revenue, Calculation Assumptions, Rate Of Return Statement of probable entitlement, calculation assumptions, rate of return, ROACE Public Utilities, Statement Of Probable Entitlement, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity Public Utilities, Statement Of Probable Entitlement, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity Stipulated settlement letter, rate of return ROACE Public Utilities, Stipulated Settlement Letter, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity Public Utilities, Stipulated Settlement Letter, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity Revenue, calculation assumptions, rate of return, common equity capitalization Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Common Equity Capitalization Percentage Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Common Equity Capitalization Percentage Interim D&O, reduction in revenue requirement, pension regulatory asset Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement Of Pension Regulatory Asset Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement Of Pension Regulatory Asset Interim D&O, reduction in revenue requirement, pension contribution regulatory asset Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement Of Pension Contribution Regulatory Asset Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement Of Pension Contribution Regulatory Asset Interim D&O, reduction in revenue requirement, pension contribution regulatory asset in 2011 Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement Of Pension Contribution Regulatory Asset Established In 2011 Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement Of Pension Contribution Regulatory Asset Established In 2011 Interim D&O, reduction in revenue requirement, baseline plant additions Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement, Baseline Plant Additions Public Utilities, Interim Decision And Order, Reduction In Revenue Requirement, Baseline Plant Additions General rate increase, revenue, percent Public Utilities, General Rate Increase, Revenue, Percent Public Utilities, General Rate Increase, Revenue, Percent Revenue, calculation assumptions rate base Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Base Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Base Conditional general rate increase amount Public Utilities, Conditional General Rate Increase, Revenue Public Utilities, Conditional General Rate Increase, Revenue Conditional general rate increase, revenue Public Utilities, Conditional General Rate Increase, Revenue, Percentage Public Utilities, Conditional General Rate Increase, Revenue, Percentage Stipulated return on average common equity rate Public Utilities, Stipulated Return On Average Common Equity Rate Public Utilities, Stipulated Return On Average Common Equity Rate General rate increase, return on average common equity percent decrease Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity, Percentage Decrease Public Utilities, General Rate Increase, Revenue, Calculation Assumptions, Rate Of Return, Return On Average Common Equity, Percentage Decrease Interim general rate increase Public Utilities, Interim General Rate Increase Public Utilities, Interim General Rate Increase Estimated income tax expense (benefit) resulting from Tax Act Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Amount of reasonable estimate for income tax expense (benefit) from effect of Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete. Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] NextEra Energy, Inc Merger NextEra Energy, Inc Merger [Member] NextEra Energy, Inc Merger [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Merger contract termination fee Proceeds from Merger Termination Fee Proceeds from Merger Termination Fee Maximum expenses paid to party for cancellation of merger Proceeds from Merger Related Cost Reimbursement Proceeds from Merger Related Cost Reimbursement Gain (loss) recognized, merger termination Gain (Loss) Recognized, Merger Termination Gain (Loss) Recognized, Merger Termination Merger termination, merger-and-spin-off related expenses, net of taxes Gain (Loss) Recognized, Merger Termination, Merger-and-spin-off Related Expenses, Net Of Taxes Gain (Loss) Recognized, Merger Termination, Merger-and-spin-off Related Expenses, Net Of Taxes Merger termination, termination fee Gain (Loss) Recognized, Merger Termination, Termination Fee Gain (Loss) Recognized, Merger Termination, Termination Fee Merger termination, insurance reimbursements Gain (Loss) Recognized, Merger Termination, Reimbursements And Insurance Gain (Loss) Recognized, Merger Termination, Reimbursements And Insurance Recognition of previously disallowed merger and acquisition expenses Effective Income Tax Rate Reconciliation, Recognition Of Previously Disallowed Merger And Acquisition Expenses Effective Income Tax Rate Reconciliation, Recognition Of Previously Disallowed Merger And Acquisition Expenses Merger termination, expenses recognized Merger Termination, Expenses Recognized Merger Termination, Expenses Recognized SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Financial Information of Parent Company Only Disclosure [Text Block] Real estate loans for investors Real Estate Loans Serviced for Investors Real estate loans serviced for investors. Loans pledged as collateral to secure advances from the FHLB of Des Moines Loans Pledged as Collateral Loans to directors, executive directors, affiliates and any related interest of such individuals Loan Balances Related to Interest of Individual Directors Executive Officers and Related Interests Represents the amount of Loan balances, which are related to interests of individuals who are directors of bank, executive officers and related interests. Loan balances, related interests of individuals who are directors Loan Balances Related to Interest of Individual Directors Represents the amount of Loan balances, which are related to interests of individuals who are directors of bank. Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities [Abstract] Increase in note receivable from subsidiary Repayments Of Notes Receivable To Subsidiaries Repayments Of Notes Receivable To Subsidiaries Decrease in note receivable from subsidiary Proceeds From Notes Receivable To Subsidiaries Proceeds From Notes Receivable To Subsidiaries Capital expenditures Payments to Acquire Property, Plant, and Equipment Investments in subsidiaries Payments to Acquire Interest in Subsidiaries and Affiliates Other Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Net increase (decrease) in notes payable to subsidiaries with original maturities of three months or less Proceeds from Repayments of Notes Payable to Subsidiaries Maturing in Three Months or Less Represents the cash outflow associated with notes payable to subsidiaries having initial term of payment within three months. Net increase (decrease) in short-term borrowings with original maturities of three months or less Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less Proceeds from issuance of short-term debt Proceeds from Short-term Debt Repayment of short-term debt Repayments of Short-term Debt Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Repayment of long-term debt and funds transferred for redemption of special purpose revenue bonds Repayments of Long-term Debt Withheld shares for employee taxes on vested share-based compensation Payments Related to Tax Withholding for Share-based Compensation Net proceeds from issuance of common stock Proceeds from (Repurchase of) Equity Common stock dividends Payments of Ordinary Dividends, Common Stock Other Proceeds from (Payments for) Other Financing Activities Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash and equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, January 1 Cash and cash equivalents, December 31 Cash dividends received from subsidiaries Cash Dividends Paid to Parent Company Financial Information for Subsidiaries [Table] Financial Information for Subsidiaries [Table] Table reflecting financial information for subsidiaries of the entity. Electric utility subsidiary Financial Information for Subsidiaries [Line Items] -- None. No documentation exists for this element. -- Schedule of regulatory assets Schedule of Regulatory Assets [Table Text Block] Schedule of regulatory liabilities Schedule of Regulatory Liabilities [Table Text Block] Schedule of voluntary liquidation and redemption prices of cumulative preferred stock Schedule of Voluntary Liquidation and Redemption Prices of Cumulative Preferred Stock [Table Text Block] Tabular disclosure of the prices of cumulative preferred stock in the event of voluntary liquidation or redemption. Schedule of purchases from all IPPs Schedule of Variable Interest Entities [Table Text Block] Schedule of changes in asset retirement obligation Schedule of Change in Asset Retirement Obligation [Table Text Block] Schedule of net annual incremental amounts proposed to be collected (refunded) Schedule of Annual Decoupling Filings [Table Text Block] Schedule of Annual Decoupling Filings [Table Text Block] Schedule of consolidating statements of income Condensed Income Statement [Table Text Block] Schedule of consolidating statements of comprehensive income Schedule of Condensed Consolidating Statements of Comprehensive Income [Table Text Block] Tabular disclosure of condensed consolidating comprehensive income. Schedule of consolidating balance sheets Condensed Balance Sheet [Table Text Block] Schedule of consolidating statements of changes in common stock equity Schedule of Condensed Consolidating Statements of Changes in Common Stock Equity [Table Text Block] Tabular disclosure of changes in condensed consolidating common stock equity. Schedule of consolidating statements of cash flows Condensed Cash Flow Statement [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Inputs, Assets, Quantitative Information [Table] Fair Value Inputs, Assets, Quantitative Information [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Residential loan Residential Mortgage [Member] Loans Loans [Member] Real estate acquired in settlement of loans Real Estate Acquired in Settlement of Loans [Member] Represents the portfolio segment of the entity's total financing receivables related to real estate acquired in settlement of loans financing receivables. Valuation Technique [Axis] Valuation Technique [Axis] Valuation Technique [Domain] Valuation Technique [Domain] Sales price Valuation, Sales Price [Member] Valuation, Sales Price [Member] Fair value of property or collateral Fair Value of Property or Collateral [Member] Represents the fair value of property or collateral valuation technique used to measure fair value. Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Weighted Average Weighted Average [Member] Fair value measurements Fair Value Inputs, Assets, Quantitative Information [Line Items] Fair value Assets, Fair Value Disclosure Selling cost Fair Value Assumptions, Selling Cost, Percent Fair Value Assumptions, Selling Cost, Percent Appraised value Fair Value Inputs Appraised Value Rate Represents the appraised value used as an input to measure fair value, expressed as a percentage. Appraised value, weighted average rate Fair Value Assumptions, Appraised Value, Weighted Average Rate Fair Value Assumptions, Appraised Value, Weighted Average Rate Quarterly Financial Information Disclosure [Abstract] Quarterly information (unaudited) Quarterly Financial Information [Text Block] Statement of Comprehensive Income [Abstract] Foreign currency hedge net unrealized loss, (taxes) benefits Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Reclassification adjustment to net income, tax (benefits) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Net gains (losses) arising during the period, (taxes) benefits Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax Amortization of transition obligation, prior service credit and net losses recognized during the period, tax benefits Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, (taxes) benefits Other Comprehensive Income, Reclassification Adjustment for Impact of Decision and Orders of the P U C Included in Regulatory Assets, Tax The amount of income taxes on the reclassification adjustments on pension and post retirement benefits for the accounting impact of the decisions issued by the Public Utilities Commission. Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Mortgage-related securities - FNMA, FHLMC and GNMA Collateralized Mortgage Backed Securities [Member] Federal Home Loan Bank Branch [Axis] Federal Home Loan Bank Branch [Axis] Federal Home Loan Bank Branch [Domain] Federal Home Loan Bank Branch [Domain] FHLB Des Moines Federal Home Loan Bank of Des Moines [Member] Available-for-sale securities Schedule of Available-for-sale Securities [Line Items] Amortized Cost Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis Due after five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis Due after ten years Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis Total amortized cost Available-for-sale Debt Securities, Amortized Cost Basis Mortgage-related securities-FNMA, FHLMC and GNMA - amortized cost Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Total available-for-sale securities, amortized cost Available-for-sale Securities, Amortized Cost Basis Mortgage-related securities-FNMA, FHLMC and GNMA, amortized cost basis Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis Held-to-maturity Securities Held-to-maturity Securities Fair value Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Due after five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Due after ten years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Total fair value Available-for-sale Securities, Debt Securities Mortgage-related securities-FNMA, FHLMC and GNMA - fair value Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Estimated fair value Available-for-sale Securities Mortgage-related securities - FNMA, FHLMC and GNMA, Fair Value Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value Held-to-maturity securities, Fair Value Held-to-maturity Securities, Fair Value Gains (losses) from sales of available-for-sale investments Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract] Proceeds Proceeds from Sale of Available-for-sale Securities Gross gains Available-for-sale Securities, Gross Realized Gains Gross losses Available-for-sale Securities, Gross Realized Losses Interest income from taxable and non-taxable investment securities Interest Income, Securities, Operating, by Taxable Status [Abstract] Taxable Interest Income, Securities, Operating, Taxable Non-taxable Interest Income, Securities, Operating, Tax Exempt Total Interest Income, Operating Available-for-sale securities pledged at carrying value Available for sale Securities, Pledged at Carrying Value as Collateral The carrying value of available-for-sale securities that serve as collateral for deposits and borrowings. Available-for-sale securities, pledged at carrying value as collateral for securities sold under agreements to repurchase Available-for-sale Securities, Pledged at Carrying Value as Collateral for Securities Sold under Repurchase Agreement Represents the carrying value of available-for-sale securities that serve as collateral for borrowings, sold under agreements to repurchase. Cost method investments Cost Method Investments Long-term Debt, Unclassified [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Special purpose revenue bonds issued on behalf of electric utility subsidiaries Bonds Issued on Behalf of Electric Utility Subsidiaries [Member] Represents the information pertaining to special revenue purpose bonds issued on behalf of subsidiaries by the parent company. Hamakua Energy, LLC Loan at 4.02% Due 2030 Hamakua Energy, LLC Loan At 4.02% Due 2030 [Member] Hamakua Energy, LLC Loan At 4.02% Due 2030 [Member] Senior Notes 2.99% Due 2022 Senior Notes 2.99 Percent Due 2022 [Member] Senior Notes 2.99 Percent Due 2022 [Member] HEI 5.67% senior notes, due 2021 Senior Notes 5.67 Percent Due 2021 [Member] Represents the information pertaining to senior notes, bearing an interest rate of 5.67 percent, due in 2021. HEI 3.99% senior notes, due 2023 Series 2013A Senior Notes 3.99 Percent Due2023 [Member] Represents information pertaining to the Series 2013 A Senior notes, bearing an interest rate of 3.99 percent, which are due in 2023. HEI Term loans (LIBOR 0.75%), paid in 2017 HEI Term Loan, LIBOR Plus .75% Due 2017 [Member] HEI Term Loan, LIBOR Plus .75% Due 2017 [Member] Eurodollar Term Loan Eurodollar Term Loan [Member] Eurodollar Term Loan [Member] Refunding Series 2007B Special Purpose Revenue Bonds Refunding Series 2007 B Due 2026 Debt 4.60 Percent [Member] This element represents Special Purpose Revenue Bonds, 4.60%, refunding series 2007B, due 2026. Bank of America Loan Agreement Bank Of America Loan Agreement [Member] Bank Of America Loan Agreement [Member] Refunding Series 2017A Special Purpose Revenue Bonds Refunding Series 2017A Special Purpose Revenue Bonds [Member] Refunding Series 2017A Special Purpose Revenue Bonds [Member] Refunding Series 2017B Special Purpose Revenue Bonds Refunding Series 2017B Special Purpose Revenue Bonds [Member] Refunding Series 2017B Special Purpose Revenue Bonds [Member] Series 2007A Special Purpose Revenue Bonds Series 2007A Special Purpose Revenue Bonds [Member] Series 2007A Special Purpose Revenue Bonds [Member] 4.31%, Series 2017A, due 2047 Unsecured Senior Notes, At 4.31 Percent And Due 2047 [Member] Unsecured Senior Notes, At 4.31 Percent And Due 2047 [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior notes Senior Notes [Member] Term loan Secured Debt [Member] Unsecured Debt Unsecured Debt [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR London Interbank Offered Rate (LIBOR) [Member] Electric utility Electric Utility Segment [Member] Represents information about the electric utility business segment of the company. Certain subsidiaries of the company are regulated operating public utilities engaged in the production, purchase, transmission, distribution and sale of electricity. Long-term debt Debt Instrument [Line Items] Long-term debt, net—other than bank Gross long-term debt Long-term Debt, Gross Less unamortized debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Line of credit facility basis point spread Debt Instrument, Basis Spread on Variable Rate Debt instrument, stated interest rate Debt Instrument, Interest Rate, Stated Percentage Aggregate principal payments Long-term Debt, Fiscal Year Maturity [Abstract] 2018 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2019 Long-term Debt, Maturities, Repayments of Principal in Year Two 2020 Long-term Debt, Maturities, Repayments of Principal in Year Three 2021 Long-term Debt, Maturities, Repayments of Principal in Year Four 2022 Long-term Debt, Maturities, Repayments of Principal in Year Five Proceeds from issuance of debt Proceeds from Issuance of Unsecured Debt Debt instrument term Debt Instrument, Term Aggregate repurchased principal amount Debt Instrument, Repurchased Face Amount Debt instrument, face amount Debt Instrument, Face Amount Repayments of unsecured debt Repayments of Unsecured Debt Short-term Debt [Abstract] Short-term borrowings Short-term Debt [Text Block] Accounting Policies [Abstract] Schedule of future minimum lease payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Summary of amounts in income tax expense related to investments in qualifying affordable housing projects Summary Of Amounts In Income Tax Expense, Affordable Housing Projects [Table Text Block] Summary Of Amounts In Income Tax Expense, Affordable Housing Projects [Table Text Block] Schedule of Impaired Financing Receivable [Table] Schedule of Impaired Financing Receivable [Table] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Troubled debt restructurings Financing Receivable, Impaired [Line Items] Period of interest-only monthly payment term loan Financing Receivable Modifications Period of Interest Only Monthly Payment Term Loan Represents the period of interest-only monthly payment term loan under the troubled debt restructuring plan. Extension of maturity date Financing Receivable Modifications Increase in Maturity Period Represents the extension of maturity period of troubled debt under the troubled debt restructuring plan. Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Consolidated subsidiary Consolidated Subsidiary [Member] Consolidated Subsidiary [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Management and administrative services Management and Administrative Services [Member] Management and Administrative Services [Member] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Obligation to contribute additional capital under the Capital Maintenance Agreement Obligation to Contribute Additional Capital under Capital Maintenance Agreement Represent the amount of maximum obligation to contribute additional capital under the Capital Maintenance Agreement. Reduction in obligation to contribute additional capital under the Capital Maintenance Agreement Remaining Obligation to Contribute Additional Capital under Capital Maintenance Agreement Represent the remaining amount of maximum obligation to contribute additional capital under the Capital Maintenance Agreement. Cash dividends paid Revenue from related party Revenue from Related Parties Prepaid assessment rate for financial institutions, lowest risk category Prepaid Assessment Rate for Financial Institutions in Lowest Risk Category Represents the rate used to determine the prepaid risk-based assessments for financial institutions in the lowest risk category. Prepaid assessment rate for financial institutions, highest risk category Prepaid Assessment Rate for Financial Institutions in Highest Risk Category Represents the rate used to determine the prepaid risk-based assessments for financial institutions in the highest risk category. Schedule of Condensed Financial Statements [Table] Condensed Financial Statements [Table] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Cash and due from banks Interest-bearing deposits Interest-bearing Deposits in Banks and Other Financial Institutions Restricted cash Restricted Cash and Cash Equivalents Investment securities Investments [Abstract] Available-for-sale, at fair value Held-to-maturity, at amortized cost (fair value of $44,412 and nil, respectively) Stock in Federal Home Loan Bank, at cost Federal Home Loan Bank Stock Loans receivable held for investment Loans and Leases Receivable, Net of Deferred Income Allowance for loan losses Loans and Leases Receivable, Allowance Total loans, net Loans and Leases Receivable, Net Amount Loans held for sale, at lower of cost or fair value Loans Receivable Held-for-sale, Net, Not Part of Disposal Group Other Goodwill Goodwill Deposit liabilities–noninterest-bearing Noninterest-bearing Deposit Liabilities Deposit liabilities–interest-bearing Interest-bearing Deposit Liabilities Other borrowings Other Borrowings Commitments and contingencies Common stock Common Stock, Value, Issued Additional paid in capital Additional Paid in Capital, Common Stock Net unrealized losses on securities Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Retirement benefit plans Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Accumulated other comprehensive loss, net of tax benefits Other assets Other Assets [Abstract] Bank-owned life insurance Bank Owned Life Insurance Premises and equipment, net Prepaid expenses Prepaid Expense Accrued interest receivable Interest Receivable Mortgage servicing rights Servicing Asset at Amortized Cost Low-income housing investments Affordable Housing Program Equity Investment Affordable Housing Program Equity Investment Real estate acquired in settlement of loans, net Real Estate Acquired Through Foreclosure Other Other Assets, Miscellaneous Total other assets Other liabilities Other Liabilities [Abstract] Accrued expenses Accrued Liabilities Federal and state income taxes payable Accrued Income Taxes Cashier’s checks Cashier Checks Cashier's check is a check drawn directly on a customer's account, making the bank the primary obligor, and assuring firm that the amount will be paid. Advance payments by borrowers Advance Payments by Borrowers for Taxes and Insurance Other Other Sundry Liabilities Total other liabilities Held-to-maturity investment securities Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Interest and dividend income Interest and Dividend Income, Operating Noninterest income Noninterest Income Revenues Total interest expense Provision for loan losses Provision for Loan Losses Expensed Noninterest expense Noninterest Expense Schedule of Regulatory Assets and Liabilities [Table] Schedule of Regulatory Assets and Liabilities [Table] A table of assets and liabilities that are created when regulatory agencies permit public utilities to defer certain costs and revenues that are included in rate-setting to the balance sheet. Regulatory Asset [Axis] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset [Domain] Retirement benefit plans, regulatory assets Retirement Benefit Cost Asset [Member] Represents regulatory assets related to retirement benefit plans including prepaid pensions, as well as pension and OPEB tracking mechanisms. Income taxes Deferred Income Tax Charge [Member] Decoupling revenue balancing account Decoupling Revenue Balancing Account [Member] Represents a separate account established and used to track and accumulate over- or under-collections, in order to defer the adjustment and smooth out unusual spikes in rates. Typically this kind of account is used when adjustments are scheduled to occur less frequently. Unamortized expense and premiums on retired debt and equity issuances Unamortized Expense and Premiums on Retired Debt and Equity Issuances [Member] Represents the amount of regulatory assets related to unamortized expense and premiums on retired debt and equity issuances. Vacation earned, but not yet taken Recoverable Vacation Pay [Member] Other, regulatory assets Other Regulatory Asset [Member] Represents regulatory assets not elsewhere enumerated. Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Current assets Current Assets [Member] Represents information pertaining to the primary financial statement caption in which the reported facts about current assets have been included. Long-term assets Long Term Assets [Member] Represents information pertaining to the primary financial statement caption in which the reported facts about long-term assets have been included. Current liabilities Current Liabilities [Member] Current Liabilities [Member] Long-term liabilities Long-term Liabilities [Member] Long-term Liabilities [Member] Regulatory Liability [Axis] Regulatory Liability [Axis] Regulatory Liability [Domain] Regulatory Liability [Domain] Cost of removal in excess of salvage value Cost of Removal in Excess of Salvage Value [Member] Represents the amount of regulatory liabilities related to cost of removal in excess of salvage value. Retirement benefit plans, regulatory liabilities Pension Costs [Member] Other, regulatory liabilities Other Regulatory Liability [Member] Represents regulatory liabilities not elsewhere enumerated. Regulatory asset and liabilities Regulatory Asset and Liabilities [Line Items] -- None. No documentation exists for this element. -- Regulatory assets Regulatory Assets 1 [Abstract] -- None. No documentation exists for this element. -- Regulatory assets Regulatory Assets Authorized amortization or recovery periods Regulatory Noncurrent Asset, Amortization Period, Duration The amortization period for recovery of the individual regulatory noncurrent asset in a schedule of regulatory noncurrent assets. Remaining amortization or recovery periods Regulatory Noncurrent Asset, Remaining Amortization or Recovery Period The remaining amortization period for recovery of the individual regulatory noncurrent asset in a schedule of regulatory noncurrent assets. Regulatory liabilities Regulatory Liabilities 1 [Abstract] -- None. No documentation exists for this element. -- Regulatory liabilities Regulatory Liabilities Authorized amortization or recovery periods Regulatory Noncurrent Liability, Amortization Period, Duration The amortization period for recovery of the individual regulatory noncurrent liability in a schedule of regulatory noncurrent liabilities. Remaining amortization or recovery periods Regulatory Liability Remaining Amortization or Recovery Period The remaining amortization period for the individual regulatory liability in a schedule of regulatory liabilities. Schedule of Assets Sold under Agreements to Repurchase [Table] Schedule of Assets Sold under Agreements to Repurchase [Table] Government entities Government Entities [Member] Government Entities [Member] Commercial account holders Commercial Account Holders [Member] Represents information pertaining to commercial account holders, a counterparty to the agreement. Securities or Other Assets Sold under Agreements to Repurchase [Axis] Securities or Other Assets Sold under Agreements to Repurchase [Axis] Assets Sold under Agreements to Repurchase, Type [Domain] Assets Sold under Agreements to Repurchase, Type [Domain] Identical securities Identical Securities [Member] Represents the information pertaining to identical securities. Securities sold under agreements to repurchase Assets Sold under Agreements to Repurchase [Line Items] Gross amount of recognized liabilities Securities Sold under Agreements to Repurchase, Gross Gross amount offset in the Balance Sheet Securities Sold under Agreements to Repurchase, Asset Net amount of liabilities presented in the Balance Sheet Securities Sold under Agreements to Repurchase Financial instruments Securities Sold under Agreements to Repurchase Collateral Right to Reclaim Financial Instruments Amount of right to receive financial instruments collateral under master netting arrangements that have not been offset against securities sold under agreement to repurchase. Cash collateral pledged Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash Fair value of collateral, percent of fair value Securities Sold Under Agreements To Repurchase, Fair Value Of Collateral, Percent Of Fair Value Securities Sold Under Agreements To Repurchase, Fair Value Of Collateral, Percent Of Fair Value Repurchase liability Assets Sold under Agreements to Repurchase, Repurchase Liability Average amount outstanding during the year Assets Sold under Agreements to Repurchase, Average Repurchase Liability Average amount to be repaid to the counterparty to the repurchase agreement at a future date. Maximum amount outstanding as of any month-end Assets Sold under Agreements to Repurchase, Maximum Repurchase Liability Maximum amount to be repaid to the counterparty to the repurchase agreement at a future date. Weighted-average interest rate as of end of the period Assets Sold under Agreements to Repurchase, Interest Rate Weighted-average interest rate during the year Assets Sold under Agreements to Repurchase, Interest Rate During Period Represents the interest rate on assets sold under agreements to repurchase. Weighted-average remaining days to maturity as of end of the period Assets Sold under Agreements to Repurchase, Remaining Maturity Period Weighted-average remaining period of maturity for a group of securities or other assets sold under repurchase agreements, as of end of the period. HEI loan 2.99%, due 2022 Senior Notes 4.41 Percent Due 2016 [Member] Represents the information pertaining to senior notes, bearing an interest rate of 4.41 percent, due in 2016. Variable Rate [Domain] Underlying Asset Class [Axis] Underlying Asset Class [Axis] Underlying Asset Class [Domain] Underlying Asset Class [Domain] Self Insured United States Longshore and Horbor Bond Self Insured United States Longshore and Horbor Bond [Member] Represents information pertaining to the entities self-insured United States Longshore & Horbour bond. Self Insured Automobile Bond Self Insured Automobile Bond [Member] Represents information pertaining to the entities self-insured automobile bonds. Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common stock Common Stock Including Additional Paid in Capital [Member] Maximum undiscounted exposure Guarantor Obligations, Maximum Exposure, Undiscounted Accounts receivable reduction Notes Reduction HEI notes payable increase to ASHI Notes Issued Notes receivable converted into equity Notes Receivable Converted To Equity Notes Receivable Converted To Equity Issuance of common stock, net of expenses Stock Issued During Period Value Dividend Reinvestment and Stock Purchase Plan The value of stock that is newly issued during the period from a dividend reinvestment and stock purchase plan (DRIP). The DRIP allows the holder of the stock to reinvest dividends paid to them by the entity in stock of the entity and to make optional cash investments in stock of the entity. Bank Banking Segment [Member] Represents information about the banking business segment of the company. Other Other Segments [Member] Expenses Total expenses Operating income (loss) Operating Income (Loss) [Abstract] Interest expense, net – other than on deposit liabilities and other bank borrowings Interest Expense on Other than Deposits and Bank Borrowings The amount of interest expense, other than on deposit liabilities and other bank borrowings. Basic earnings per common share (in dollars per share) Earnings Per Share, Basic Diluted earnings per common share (in dollars per share) Earnings Per Share, Diluted Weighted-average number of common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Net effect of potentially dilutive shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted-average shares assuming dilution (in shares) Weighted Average Number of Shares Outstanding, Diluted Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Mauo, LLC Mauo, LLC [Member] Mauo, LLC [Member] Secured Debt Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Intersegment eliminations Intersegment Eliminations [Member] Segment financial information Segment Reporting Information [Line Items] Power produced by power plants (in megawatts) Public Utilities, Power Produced By Power Plant Public Utilities, Power Produced By Power Plant Proceeds from issuance of secured notes Proceeds from Issuance of Secured Debt Power storage capacity (in megawatt hours) Public Utilities, Power Storage Capacity Public Utilities, Power Storage Capacity Power purchase agreement term Public Utilities, Power Purchase Agreement, Term Public Utilities, Power Purchase Agreement, Term Power purchase agreement extension term Public Utilities, Power Purchase Agreement, Term Extension Period Public Utilities, Power Purchase Agreement, Term Extension Period Revenues Depreciation and amortization Depreciation, Depletion and Amortization Income (loss) before income taxes Income taxes (benefit) Capital expenditures Assets Securities or Other Assets Sold under Agreements to Repurchase, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Assets Sold under Agreements to Repurchase, Maturity Period [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Overnight Maturity Overnight [Member] 1 to 29 days Maturity Less than 30 Days [Member] 30 to 90 days Maturity 30 to 90 Days [Member] Over 90 days Maturity Greater than 90 Days [Member] Collateralized by mortgage-related securities and federal agency obligations US Government Agencies Debt Securities And Mortgage Backed Securities [Member] US Government Agencies Debt Securities And Mortgage Backed Securities [Member] Weighted-average interest rate Collateralized by mortgage-related securities and federal agency obligations at fair value plus accrued interest Assets Sold Under Agreements To Repurchase Fair Value Plus Accrued Interest Assets Sold Under Agreements To Repurchase Fair Value Plus Accrued Interest Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Equity and Incentive Plan (EIP) Equity and Incentive Plan [Member] Represents Equity and Incentive Plan (EIP) as awarded by a company to their employees as a form of incentive compensation. Nonemployee Director Stock Plan Nonemployee Director Stock Plan [Member] Nonemployee Director Stock Plan [Member] Restricted shares Restricted Stock [Member] Long-term incentive plan (LTIP) Long-term Incentive Plan [Member] Represents Long-term incentive plan (LTIP) as awarded by a company to their employees as a form of incentive compensation. LTIP linked to TRS Long-term Incentive Plan Linked to Total Return to Shareholders [Member] Represents Long-term incentive plan (LTIP) as awarded by a company to their employees based on total return to shareholders (TRS). Stock Compensation Plan Stock Compensation Plan [Member] Restricted stock units Restricted Stock Units (RSUs) [Member] LTIP awards linked to other performance conditions Long-term Incentive Plan Awards Linked to Other Performance Conditions [Member] Represents Long-term incentive plan (LTIP) as awarded by a company to their employees based on other performance conditions. Share-based compensation Additional shares available for issuance Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Shares remaining available for future issuance Share Based Compensation Arrangement, Number of Shares that could be Issued Upon Vesting of Restricted Stock Units and Long Term Incentive Plans Represents the number of authorized but unissued shares that could be issued under the equity-based compensation plan. Shares that can be issued upon vesting of outstanding units and achievement of performance goals Share-based Compensation Number of Shares that could be Issued upon Vesting and Achievement of Performance Goals Represents the number of shares that could be issued upon vesting of share-based payment awards and achievement of performance goals. The number of equal annual increments for which the awards become unrestricted (in installments) Share-based Compensation Arrangement by Share-based Payment Award, Annual Increments upon which Restricted Awards Become Unrestricted Number The number of annual increments, on the anniversaries of the grant date, upon which restricted awards become unrestricted. Performance period Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Period Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Period Exception to forfeiture, minimum requisite service period Share-based Compensation Arrangement by Share-based Payment Award, Award Exception to Forfeiture Requisite Service Period, Minimum Represents the requisite minimum months of service in the performance period required in order to qualify for the forfeiture exception in the event of death, disability and retirement, on completion of requisite minimum months of service. Shares remaining available for future issuance Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Share-based compensation expense (in dollars) Allocated Share-based Compensation Expense Unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted-average period over which unrecognized compensation cost expected to be recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Payout low end of range Share-based Compensation by Share-based Payment Award Payout, Low of Range Represents the low end of range of payout depending on achievement of the goals. Payout high end of range Share-based Compensation by Share-based Payment Award Payout High End of Range Represents the high end of range of payout depending on achievement of the goals. Intrinsic value of shares exercised Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options Exercises in Period, Intrinsic Value The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) during the reporting period. Tax benefit realized for the deduction of exercises Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Tax Benefit Realized from Exercise of Stocks Disclosure of the aggregate tax benefit realized from the exercise of stocks and the conversion of similar instruments during the annual period. Statement of Cash Flows [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Other amortization Amortization Provision for loan losses Provision for Loan and Lease Losses Impairment of utility assets Asset Impairment Charges Loans receivable originated and purchased, held for sale Payments for Origination and Purchases of Loans Held-for-sale Proceeds from sale of loans receivable, held for sale Proceeds from Sale of Loans Held-for-sale Deferred income taxes Deferred Income Tax Expense (Benefit) Share-based compensation expense Share-based Compensation Allowance for equity funds used during construction Other Other Operating Activities, Cash Flow Statement Changes in assets and liabilities Increase (Decrease) in Operating Capital [Abstract] Decrease (increase) in accounts receivable and unbilled revenues, net Increase (Decrease) in Receivables Decrease (increase) in fuel oil stock Increase (Decrease) in Fuel Inventories Increase in regulatory assets Increase (Decrease) in Other Regulatory Assets Increase (decrease) in accounts, interest and dividends payable Increase (Decrease) in Accounts Payable and Interest and Dividends Payable The increase (decrease) during the reporting period in accounts, interest and dividends payable. Change in prepaid and accrued income taxes, tax credits and utility revenue taxes Increase (Decrease) In Prepaid And Accrued Income Taxes, Tax Credits, And Utility Revenue, Taxes Increase (Decrease) In Prepaid And Accrued Income Taxes, Tax Credits, And Utility Revenue, Taxes Increase (decrease) in defined benefit pension and other postretirement benefit plans liability Increase (Decrease) in Pension and Postretirement Obligations Change in other assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by operating activities Cash flows from investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Available-for-sale investment securities purchased Payments to Acquire Available-for-sale Securities Principal repayments on available-for-sale investment securities Proceeds from Principal Repayments on Investment and Mortgage Related Securities The net cash inflow (outflow) resulting from principal repayments on investment and mortgage-related securities. Proceeds from sale of available-for-sale investment securities Purchases of held-to-maturity investment securities Payments to Acquire Held-to-maturity Securities Purchase of stock from Federal Home Loan Bank Payments to Acquire Federal Home Loan Bank Stock Redemption of stock from Federal Home Loan Bank Proceeds from Sale of Federal Home Loan Bank Stock Net decrease (increase) in loans held for investment Payments for (Proceeds from) Loans and Leases Proceeds from sale of commercial loans Proceeds from Sale of Loans Receivable Proceeds from sale of real estate acquired in settlement of loans Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans Proceeds from sale of real estate held for sale Proceeds from Sale of Property Held-for-sale Contributions in aid of construction Proceeds from Contribution in Aid of Construction Contributions to low income housing investments Payments for Affordable Housing Programs Acquisition of business Payments to Acquire Businesses, Net of Cash Acquired Net increase in deposit liabilities Increase (Decrease) in Deposits Net increase (decrease) in retail repurchase agreements Increase (Decrease) in Retail Repurchase Agreements The decrease in retail repurchase agreements, during the period. Proceeds from other bank borrowings Proceeds from Other Bank Borrowings The amount of cash inflows resulting from other bank borrowings. Repayments of other bank borrowings Repayments of Other Bank Borrowings The amount of cash outflows resulting from repayment of other bank borrowings. Withheld shares for employee taxes on vested share-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Net proceeds from issuance of common stock Preferred stock dividends of subsidiaries Payments of Ordinary Dividends, Noncontrolling Interest Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Affiliated Entity Affiliated Entity [Member] Hawaii Medical Service Association (HMSA) Hawaii Medical Service Association (HMSA) [Member] Hawaii Medical Service Association (HMSA) [Member] Hawaii Dental Service (HDS) Hawaii Dental Service (HDS) [Member] Hawaii Dental Service (HDS) [Member] Gross costs Related Party Expense, Gross [Member] Related Party Expense, Gross [Member] Net expense Related Party Expense, Net [Member] Related Party Expense, Net [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Expenses from related party transactions Related Party Transaction, Expenses from Transactions with Related Party Regulatory restrictions on net assets Regulatory Restrictions on Net Assets Disclosure [Text Block] Entire disclosure of regulatory agencies restrictions on net asset and limitations on transfers out of the company. Electric utility subsidiary [Abstract] Electric utility subsidiary [Abstract] Amount charged to subsidiaries for general management and administrative services Related Party Transaction, Amounts of Transaction Effective interest rate basis term Debt Instrument Interest Rate Basis Term of Commercial Paper Represents the term of commercial paper, the average effective interest rate of which is used as a basis for calculating the interest rate of the debt instrument. Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Hawaii Electric Light Company, Inc. (HELCO) Subsidiaries Two [Member] This element represents Hawaii Electric Light Company, Inc., an electric utility subsidiary of Hawaiian Electric Company, Inc. Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series C, D, E, H, J and K Preferred Stock Multiple Series Preferred Stock [Member]