Bank Subsidiary [Abstract] Bank Subsidiary [Abstract] Servicing Asset at Amortized Cost [Table] Servicing Asset at Amortized Cost [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] American Savings Bank (ASB) American Savings Bank FSB [Member] American Savings Bank FSB Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Residential loan Residential Mortgage [Member] Servicing contracts Servicing Contracts [Member] Measurement Band A Measurement Band A [Member] Measurement Band A [Member] Measurement Band B Measurement Band B [Member] Measurement Band B [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Note rate Measurement Input, Note Interest Rate [Member] Measurement Input, Note Interest Rate [Member] Discount rate Measurement Input, Discount Rate [Member] Prepayment speed Measurement Input, Prepayment Rate [Member] Servicing Asset at Amortized Cost [Line Items] Servicing Asset at Amortized Cost [Line Items] Proceeds from sale of mortgage loans Proceeds from Sale of Mortgage Loans Held-for-sale Gain on sale of mortgage loans Gain (Loss) on Sale of Mortgage Loans Repurchase reserve Mortgage Loans on Real Estate, Repurchase Reserve Mortgage Loans on Real Estate, Repurchase Reserve Mortgage service fees Fees and Commissions, Mortgage Banking and Servicing Gross carrying amount Servicing Asset Accumulated amortization Servicing Asset, Accumulated Amortization Servicing Asset, Accumulated Amortization Valuation allowance Valuation Allowance for Impairment of Recognized Servicing Assets, Balance Net carrying amount Servicing Asset, Net Servicing Asset, Net SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] Servicing asset - beginning balance Servicing Asset at Amortized Cost Amount capitalized Servicing Asset at Amortized Value, Amount Capitalized Servicing Asset at Amortized Value, Amount Capitalized Amortization Servicing Asset at Amortized Cost, Amortization Other-than-temporary impairment Servicing Asset at Amortized Cost, Other than Temporary Impairments Servicing asset - ending balance Valuation Allowance [Roll Forward] Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward] Valuation allowance, beginning balance Provision (recovery) Valuation Allowance for Impairment of Recognized Servicing Assets, Additions (Deductions) for Expenses (Recoveries) Valuation allowance, ending balance Measurement band percent for risk categorization Risks Inherent in Servicing Assets and Servicing Liabilities, Band Percent For Risk Categorization Risks Inherent in Servicing Assets and Servicing Liabilities, Band Percent For Risk Categorization Unpaid principal balance Fair Value Inputs, Unpaid Principal Balance, Asset Fair Value Inputs, Unpaid Principal Balance, Asset Weighted average measurement input Servicing Asset, Measurement Input Prepayment rate: Fair Value Inputs, Prepayment Rate [Abstract] Fair Value Inputs, Prepayment Rate [Abstract] 25 basis points adverse rate change Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Point Adverse Change in Prepayment Speed The hypothetical financial impact of a 25 basis point adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date. 50 basis points adverse rate change Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Point Adverse Change in Prepayment Speed Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Point Adverse Change in Prepayment Speed Discount rate: Fair Value Inputs, Discount Rate [Abstract] Fair Value Inputs, Discount Rate [Abstract] 25 basis points adverse rate change Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Points Adverse Change in Discount Rate Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Points Adverse Change in Discount Rate 50 basis points adverse rate change Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Points Adverse Change in Discount Rate Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Points Adverse Change in Discount Rate Electric utility subsidiary [Abstract] Electric utility subsidiary [Abstract] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Hawaiian Electric Company Subsidiaries [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Power purchase agreement Power Purchase Agreement [Abstract] -- None. No documentation exists for this element. -- Number of power purchase agreements (PPAs) (in agreements) Number of Power Purchase Agreements Represents the number of firm power purchase agreements entered into, by the company. Number of entities currently required to be consolidated as VIEs (in entities) Variable Interest Entity Number of Unconsolidated VIEs Represents the number of entities not required to be consolidated as VIEs. Number of IPPs Number Of Independent Power Producers Number Of Independent Power Producers Number of firm capacity producers declining to provide financial information to determine primary beneficiary status (in entities) Number of Firm Capacity Producers Declining to Provide Financial Information Represents information pertaining to number of firm capacity producers declining to provide financial information. Minimum potential number of IPP entities consolidated into company in the future (in entities) Minimum Potential Number of IPP Entities Consolidated Into Company in Future The minimum number of potential IPP's that could be required to be consolidation into the Company in the future based on new financial information provided by IIP's used to determine VIE relationship. Segment Reporting [Abstract] Schedule of segment financial information Schedule of Segment Reporting Information, by Segment [Table Text Block] 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] Equity Award [Domain] Equity Award [Domain] Restricted stock units Restricted Stock Units (RSUs) [Member] 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). 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 Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Restricted stock awards and restricted stock units Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Outstanding, beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Outstanding, end of period (in shares) Weighted-average grant-date fair value per share Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Outstanding, beginning of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeited (in dollars per share) Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Option Forfeited in Period Weighted Average Grant Date Fair Value Represents the weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect during the reporting period as a result of the occurrence of a terminating event specified in the contractual agreement of the plan or when performance conditions met. Outstanding, end of period (in dollars per share) Total weighted-average grant-date fair value Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Grants in Period Total Fair Value Represents the total weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Fair Value Disclosures [Abstract] Schedule of estimated fair values of certain of the Company's financial instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Schedule of assets measured at fair value on a recurring basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of changes in Level 3 assets and liabilities measured at fair value on a recurring basis Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Schedule of assets measured at fair value on a nonrecurring basis Fair Value Measurements, Nonrecurring [Table Text Block] Schedule of significant unobservable inputs used in the fair value measurement Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Leases [Abstract] Lease, Cost Lease, Cost [Table Text Block] Schedule of Annual Undiscounted Cash Flows on Operating Lease Liabilities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair value measurements on a nonrecurring basis Fair Value, Measurements, Nonrecurring [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Estimated fair value Estimate of Fair Value Measurement [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Fair value measurements on a recurring basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Loans, net Loans Receivable, Fair Value Disclosure Real estate acquired in settlement of loans Real Estate Acquired Through Foreclosure Adjustments to fair value of loans held for sale Loans Receivable Held for Sale Amount Fair Value Adjustments Represents the amount of fair value adjustments in loans held for sale. Bank subsidiary -- None. No documentation exists for this element. -- Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Domain] Class of Financing Receivable, Type [Domain] Commercial Portfolio Segment Commercial Portfolio Segment [Member] Commercial real estate Commercial Real Estate Portfolio Segment [Member] Commercial construction Construction Loans [Member] Commercial loans Commercial Loan [Member] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Pass Pass [Member] Special mention Special Mention [Member] Substandard Substandard [Member] Doubtful Doubtful [Member] Loss Unlikely to be Collected Financing Receivable [Member] Credit risk profile by internally assigned grade for loans Financing Receivable, Recorded Investment [Line Items] Loans and leases receivable before fees, gross Financing Receivable, Net Amortized cost Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract] Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after ten years Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost Total amortized cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost Amortized cost Debt Securities, Available-for-sale, Amortized Cost Held-to-Maturity, Debt Securities, Amortized Cost [Abstract] Held-to-Maturity, Debt Securities, Amortized Cost [Abstract] Held-to-Maturity, Debt Securities, Amortized Cost [Abstract] Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost Amortized cost Debt Securities, Held-to-maturity Fair value Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] Available-for-sale Securities, Debt Securities, Fair Value [Abstract] Available-for-sale Securities, Debt Securities, Fair Value [Abstract] Available-for-sale Securities, Debt Securities, Fair Value [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Total fair value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Total available-for-sale securities Debt Securities, Available-for-sale Held-to-maturity Securities, Debt Securities, Fair Value [Abstract] Held-to-maturity Securities, Debt Securities, Fair Value [Abstract] Held-to-maturity Securities, Debt Securities, Fair Value [Abstract] Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Fair Value Total held-to-maturity securities Debt Securities, Held-to-maturity, Fair Value Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] 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. 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. Residential construction Residential Construction Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to residential construction. Consumer loans Consumer Loan [Member] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Domain] Financing Receivables, Period Past Due [Domain] 30-59 days past due Financing Receivables, 30 to 59 Days Past Due [Member] 60-89 days past due Financing Receivables, 60 to 89 Days Past Due [Member] Greater than 90 days Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Credit risk profile based on payment activity for loans Financing Receivable, Recorded Investment, Past Due [Line Items] Total past due Financing Receivable, Recorded Investment, Past Due Current Financing Receivable, Recorded Investment, Current Total financing receivables Recorded Investment greater than 90 days and accruing Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Offsetting Liabilities [Table] Offsetting Liabilities [Table] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Commercial account holders Commercial Account Holders [Member] Represents information pertaining to commercial account holders, a counterparty to the agreement. Offsetting Liabilities [Line Items] Offsetting Liabilities [Line Items] FHLB advances Federal Home Loan Bank Advances Gross amount of recognized liabilities Securities Sold under Agreements to Repurchase, Gross Gross amount offset in the Balance Sheets Securities Sold under Agreements to Repurchase, Asset Securities sold under agreements to repurchase Securities Sold under Agreements to Repurchase Securities sold under agreements to repurchase collateral, 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. Securities sold under agreements to repurchase, cash collateral pledged Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash Condensed Income Statement [Table] Condensed Income Statement [Table] Hawaiian Electric (parent only) Hawaiian Electric, Parent [Member] Hawaiian Electric, Parent [Member] HELCO Hawaii Electric Light Company, Inc [Member] Hawaii Electric Light Company, Inc [Member] Maui Electric Maui Electric Company Limited [Member] Maui Electric Company Limited [Member] Other subsidiaries Renewable Hawaii and Uluwehiokama Biofuels Company [Member] Represents the information pertaining to Renewable Hawaii company, a wholly owned subsidiary of the entity. It also represents the information pertaining to Uluwehiokama Biofuels company, a non-regulated subsidiary of the entity. Hawaiian Electric Company, Inc. and Subsidiaries Hawaiian Electric Company and Subsidiaries [Member] Represents Hawaiian Electric Company, Inc, and Subsidiaries. Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Reportable Legal Entities Reportable Legal Entities [Member] Consolidating adjustments Eliminations And Reconciling Items [Member] Represents the aggregate total of reconciling items and elimination items Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Revenues Revenue from Contract with Customer, Excluding Assessed Tax 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 Total operating income Operating Income (Loss) Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Equity in earnings of subsidiaries Equity in Earnings of Subsidiaries Represents the amount of equity in earnings of subsidiaries. Retirement defined benefits expense—other than service costs Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component 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 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 Bank segment Bank Subsidiary [Text Block] This element encapsulates disclosures pertaining to banking subsidiary. Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] Net income for common stock Other comprehensive income (loss), net of taxes: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Retirement benefit plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent [Abstract] Adjustment for amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits Other Comprehensive Income, Reclassification of Defined Benefit Plans Net Gain (Loss), Prior Service Gain (Loss), and Net Transition Asset Obligation Recognized in Net Periodic Benefit Cost, Net of Tax The adjustment out of other comprehensive income for actuarial gains or losses, prior service gains or losses, and net transition asset or obligation recognized as a component of net periodic benefit cost during the period, after tax. Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes Other Comprehensive Income, Reclassification Adjustment for Impact of Decision and Orders of the P U C Included in Regulatory Assets, Net of Tax Reclassification adjustments on pension and post retirement benefits for the accounting impact of the decisions issued by the Public Utilities Commission, net of income taxes. Other comprehensive income (loss), net of taxes Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income attributable to Hawaiian Electric Industries, Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Statement of Comprehensive Income [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Net income for common stock Net unrealized gains (losses) on available-for-sale investment securities: Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent [Abstract] Net unrealized gain (losses) on available-for-sale investment securities arising during the period, net of tax benefits (taxes) Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Derivatives qualifying as cash flow hedges: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent [Abstract] Unrealized interest rate hedging losses arising during the period, net of tax benefits of $140 and nil, respectively Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Adjustment for amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Supplemental Cash Flow Elements [Abstract] Schedule of supplemental disclosures of cash and noncash activity Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] 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 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] Equity in earnings of subsidiaries Equity in Earnings This element represents Equity in earnings. Common stock dividends received from subsidiaries Proceeds from Dividends Received Depreciation of property, plant and equipment Depreciation Other amortization Amortization Deferred income taxes Deferred Income Tax Expense (Benefit) 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 in accounts receivable Increase (Decrease) in Accounts Receivable Decrease in accrued unbilled revenues Increase (Decrease) in Unbilled Receivables Decrease (increase) in fuel oil stock Increase (Decrease) in Fuel Inventories Increase in materials and supplies Increase (Decrease) in Raw Materials, Packaging Materials and Supplies Inventories Increase in regulatory assets Increase (Decrease) in Other Regulatory Assets Increase (decrease) in accounts payable Increase (Decrease) in Accounts Payable Change in prepaid and accrued income taxes, tax credits and revenue taxes Increase (Decrease) in Prepaid and Accrued Income Taxes and Utility Revenue, Taxes The net changes in cash flows resulting from changes in prepaid and accrued income taxes and utility revenue taxes. Increase in defined benefit pension and other postretirement benefit plans liability Increase(Decrease) in Pension and Other Postretirement Defined Benefit Plans Liability The increase (decrease) during the reporting period in the amount due to fund defined benefit pension and other postretirement benefit plans liability. Change in other assets and liabilities Increase (Decrease) In Other Operating Assets And Liabilities, Net Excluding Dividends Received From Subsidiaries And Equity In Earnings Of Subsidiaries Increase (Decrease) In Other Operating Assets And Liabilities, Net Excluding Dividends Received From Subsidiaries And Equity In Earnings Of Subsidiaries 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, Continuing Operations [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Other Payments for (Proceeds from) Businesses and Interest in Affiliates Advances (to) from affiliates 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] Common stock dividends Payments of Ordinary Dividends, Common Stock Preferred stock dividends of Hawaiian Electric and subsidiaries Payments of Ordinary Dividends, Preferred Stock and Preference Stock Increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less Proceeds from other bank borrowings Proceeds from Other Bank Borrowings The amount of cash inflows resulting from other bank borrowings. Other Proceeds from (Payments for) Other Financing Activities Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents, end of period Net unrealized gains (losses) on securities arising during the period, (taxes) benefits Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Unrealized interest rate hedging gain (loss), net of tax expense (benefits), net Other Comprehensive Income (Loss), Interest Rate Hedge, Gain (Loss), before Reclassification, Tax Other Comprehensive Income (Loss), Interest Rate Hedge, Gain (Loss), before Reclassification, Tax Amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, taxes (benefits) Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax Reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, taxes 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. Equity [Abstract] Schedule of accumulated other comprehensive income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of reclassifications out of accumulated other comprehensive income/(loss) Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Schedule of Condensed Financial Statements [Table] Condensed Financial Statements [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Financial Services Financial Service [Member] Deposit Liabilities Deposit Account [Member] Other Financial Products Financial Service, Other [Member] Bank-Owned Life Insurance Bank Owned Life Insurance Income [Member] Bank Owned Life Insurance Income [Member] Mortgage Banking Mortgage Banking [Member] Other income, net Other Income, Net [Member] Other Income, Net [Member] Statements of Income Data Condensed Financial Statements, Captions [Line Items] Interest and dividend income Interest and Dividend Income, Operating [Abstract] Interest and fees on loans Interest and Fee Income, Loans and Leases Interest and dividends on investment securities Interest and Dividend Income, Securities, Operating Total interest and dividend income Interest and Dividend Income, Operating Interest expense Interest Expense [Abstract] Interest on deposit liabilities Interest Expense, Deposits Interest on other borrowings Interest Expense, Borrowings Total interest expense Interest Expense Net interest income Interest Income (Expense), Net Provision for loan losses Provision for Loan Losses Expensed Net interest income after provision for loan losses Interest Income (Expense), after Provision for Loan Loss Noninterest income Noninterest Income [Abstract] Noninterest income Revenue from Contract with Customer, Including Assessed Tax Total noninterest income Noninterest Income Noninterest expense Noninterest Expense [Abstract] Compensation and employee benefits Labor and Related Expense Occupancy Occupancy, Net Data processing Information Technology and Data Processing Services Professional Fees Equipment Equipment Expense Office supplies, printing and postage Supplies Printing and Postage Expense The aggregate amount of expenses directly related to the office supplies, printing and postage. Marketing Marketing Expense FDIC insurance Federal Deposit Insurance Corporation Premium Expense Other expense Other Noninterest Expense Total noninterest expense Noninterest Expense Regulatory Projects and Legal Obligations [Table] Regulatory Projects and Legal Obligations [Table] Discloses the components of regulatory projects and legal obligations. 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. 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. Hawaii Electric Light Company, Inc. (HELCO) 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, LLC Hu Honua Bioenergy, LLC [Member] Hu Honua Bioenergy, LLC [Member] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Domain] Environmental Remediation Contingency [Domain] PCB Contamination PCB Contamination [Member] PCB Contamination [Member] Regulatory Projects and Legal Obligations [Line Items] Regulatory Projects and Legal Obligations [Line Items] -- None. No documentation exists for this element. -- Revenue subject to refund Public Utility, Revenue Subject To Refund Public Utility, Revenue Subject To Refund Refunded amount Public Utility, Refunded Amount Public Utility, Refunded Amount Increased power purchase commitment capacity (in megawatts) Aggregate of Power Purchase Capacity Increases from Initial Capacity Aggregate of Power Purchase Capacity Increases from Initial Capacity Purchase commitment, period (in years) Long-term Purchase Commitment, Period Minimum power volume required (in megawatts) Long-term Purchase Commitment, Minimum Power Volume Required Long-term Purchase Commitment, Minimum Power Volume Required Additional capacity requirement (in megawatts) Long Term Purchase Commitment, Arbitration, Additional Capacity Requirement Long Term Purchase Commitment, Arbitration, Additional Capacity Requirement Public utility, ERP/EAM required pass through savings to customers Public Utility, ERP/EAM Required Pass-through Savings Over 12 Years Public Utility, ERP/EAM Required Pass-through Savings Over 12 Years ERP/EAM project service period (in years) Public Utility, ERP/EAM Project Service Period Public Utility, ERP/EAM Project Service Period AFUDC rate Public Utilities, Allowance for Funds Used During Construction, Rate Project costs, accrued carrying costs once put into service Public Utilities, ERP/EAM Implementation Project Costs, Accrued Carrying Costs Once Put Into Service Public Utilities, ERP/EAM Implementation Project Costs, Accrued Carrying Costs Once Put Into Service ERP/EAM implementation project, future operation and maintenance expense reductions Public Utility, ERP/EAM System, Future Operation And Maintenance Expense Reductions Public Utility, ERP/EAM System, Future Operation And Maintenance Expense Reductions ERP/EAM implementation project, future cost avoidance related to capital and tax cost Public Utility, ERP/EAM System, Future Cost Avoidance Related To Capital Cost And Tax Cost Public Utility, ERP/EAM System, Future Cost Avoidance Related To Capital Cost And Tax Cost West Lock PV Project, energy generated (in megawatts) Public Utilities, Solar Project, Facility Energy Production Public Utilities, Solar Project, Facility Energy Production West Lock PV Project, cost cap Public Utilities, Solar Project, Project Cap Public Utilities, Solar Project, Project Cap West Lock PV Project, maximum energy cost (in dollars per kilowatt hours) Public Utilities, Solar Project, Maximum Energy Cost Public Utilities, Solar Project, Maximum Energy Cost West Lock PV Project, project costs incurred Public Utilities, Solar Project, Cost Incurred Public Utilities, Solar Project, Cost Incurred Environmental regulation Environmental Remediation Obligations [Abstract] 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. Valuation allowances and reserves Accrual for Environmental Loss Contingencies Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Financing Receivable Troubled Debt Restructurings and Troubled Debt Restructurings that Subsequently Defaulted [Axis] Financing Receivable Troubled Debt Restructurings and Troubled Debt Restructurings that Subsequently Defaulted [Axis] Information related to troubled debt restructurings granted in the current period by class of financing receivable and portfolio segment and troubled debt restructurings in which a modification was made within the last 12 months and for which there was a payment default in the current reporting period by class of financing receivable and portfolio segment. Financing Receivable Troubled Debt Restructurings and Troubled Debt Restructurings that Subsequently Defaulted [Domain] Financing Receivable Troubled Debt Restructurings and Troubled Debt Restructurings that Subsequently Defaulted [Domain] Represents classes of financing receivables and portfolio segments related to trouble debt restructurings granted in the current period and troubled debt restructurings in which a modification was made within the last 12 months and for which there was a payment default in the current reporting period. Troubled debt restructurings real estate loans Financing Receivable Troubled Debt Restructurings Real Estate Loans [Member] Represents the information pertaining to troubled debt restructurings granted during the current period. Financing Receivable, Modifications [Line Items] Financing Receivable, Modifications [Line Items] Number of contracts Financing Receivable, Modifications, Number of Contracts Pre-modification outstanding recorded investment Financing Receivable, Modifications, Pre-Modification Recorded Investment Number of contracts Financing Receivable, Troubled Debt Restructuring, Contracts That Subsequently Defaulted, Number Financing Receivable, Troubled Debt Restructuring, Contracts That Subsequently Defaulted, Number Recorded investment Financing Receivable, Troubled Debt Restructuring, Contract That Subsequently Defaulted, Value Financing Receivable, Troubled Debt Restructuring, Contract That Subsequently Defaulted, Value Post-modification outstanding recorded investment Financing Receivable, Modifications, Post-Modification Recorded Investment Net increase in allowance Allowance for Loan and Lease Losses, Period Increase (Decrease) Statement of Cash Flows [Abstract] Net income Provision for loan losses Provision for Loan and Lease Losses Loans originated and purchased, held for sale Payments for Origination and Purchases of Loans Held-for-sale Proceeds from sale of loans, held for sale Proceeds from Sale of Loans Held-for-sale Share-based compensation expense Share-based Compensation Decrease (increase) in accounts receivable Decrease in accrued unbilled revenues Decrease (increase) in accounts receivable and unbilled revenues, net Increase (Decrease) in Receivables Increase in fuel oil stock Increase in materials and supplies Increase in regulatory assets Increase 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 defined benefit pension and other postretirement benefit plans liability Change in other assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net 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, Available For Sale Proceeds from Principal Repayments on Investment and Mortgage Related Securities, Available For Sale Principal repayments of held-to-maturity investment securities Proceeds from Sale and Maturity of 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 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 Contributions to low income housing investments Payments For Affordable Housing Project Investments Payments For Affordable Housing Project Investments Other Net increase in deposit liabilities Increase (Decrease) in Deposits Net increase in short-term borrowings with original maturities of three months or less Proceeds from issuance of short-term debt Proceeds from Short-term Debt Net increase (decrease) in retail repurchase agreements Increase (Decrease) in Retail Repurchase Agreements The decrease in retail repurchase agreements, during the period. Repayments of other bank borrowings Repayments of Other Bank Borrowings The amount of cash outflows resulting from repayment of other bank borrowings. Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Withheld shares for employee taxes on vested share-based compensation Payments Related to Tax Withholding for Share-based Compensation Preferred stock dividends of subsidiaries Payments of Ordinary Dividends, Noncontrolling Interest Electric utility segment [Abstract] Electric utility segment [Abstract] HPOWER Hpower [Member] Represents an independent power producer (IPP) with whom the entity has entered into a power purchase agreement. Puna Geothermal Venture Puna Geothermal Venture [Member] Puna Geothermal Venture [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. Wind IPPs Wind Independent Power Producers [Member] Wind Independent Power Producers [Member] Solar IPPs Solar Independent Power Producer [Member] Solar Independent Power Producer [Member] Other IPPs Other Independent Power Producers [Member] Represents information pertaining to other independent power producers. Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Share-based compensation expense Allocated Share-based Compensation Expense Income tax benefit Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Assets Assets [Abstract] Utility property, plant and equipment Public Utilities, 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 Non-utilities, Property, Plant and Equipment, Net Non-utilities, Property, Plant and Equipment, Net Total property, plant and equipment, net Property, Plant and Equipment, Net Investment in wholly owned subsidiaries, at equity Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Current assets Assets, Current [Abstract] Cash and cash equivalents Advances to affiliates Advances to Affiliate 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 Other long-term assets Assets Noncurrent Excluding Property Plant and Equipment Net [Abstract] -- None. No documentation exists for this element. -- Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Regulatory assets Regulatory Assets, Noncurrent 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. Total assets Assets Capitalization and liabilities Liabilities and Equity [Abstract] Capitalization Stockholder's Equity and Long Term Debt Noncurrent [Abstract] -- None. No documentation exists for this element. -- Total shareholders’ equity Stockholders' Equity Attributable to Parent Cumulative preferred stock—not subject to mandatory redemption Preferred Stock, Value, Issued 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 operating lease liabilities Operating Lease, Liability, Current Current portion of long-term debt Long-term Debt, Current Maturities Short-term borrowings from non-affiliates Short-term Debt Short-term borrowings from affiliate Due to Affiliate, Current Accounts payable Accounts Payable, Current Interest and preferred 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 Taxes Payable, Current Regulatory liabilities Regulatory Liability, Current Other Other Liabilities, Current Total current liabilities Liabilities, Current Deferred credits and other liabilities Liabilities, Other than Long-term Debt, Noncurrent [Abstract] Operating lease liabilities Operating Lease, Liability, Noncurrent 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 Liability, Defined Benefit Plan, Noncurrent Other Other Liabilities, Noncurrent Total deferred credits and other liabilities Liabilities, Other than Long-term Debt, Noncurrent Total liabilities and shareholders’ equity Liabilities and Equity Statement of Stockholders' Equity [Abstract] Common stock dividends (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Common stock Common Stock [Member] Shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Leases Lessee, Operating Leases [Text Block] Electric utility segment Electric Utility Subsidiary [Text Block] This element encapsulates disclosures pertaining to electric utility subsidiary. Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Other leases Other Operating Leases [Member] Other Operating Leases [Member] PPAs classified as leases Power Purchase Agreements Qualifying As Operating Leases [Member] Power Purchase Agreements Qualifying As Operating Leases [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Renewal option range Lessee, Operating Lease, Renewal Term Operating lease cost Operating Lease, Cost Variable lease cost Variable Lease, Cost Total lease cost Lease, Cost Other information Lease, Cost [Abstract] Cash paid for amounts included in the measurement of lease liabilities: Income and Expenses, Lessee [Abstract] Cash paid for amounts included in the measurement of lease liabilities—Operating cash flows from operating leases Operating Lease, Payments Weighted-average remaining lease term—operating leases (in years) Operating Lease, Weighted Average Remaining Lease Term Weighted-average discount rate—operating leases Operating Lease, Weighted Average Discount Rate, Percent Operating Lease Liabilities, Payments Due [Abstract] Operating Lease Liabilities, Payments Due [Abstract] 2019 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2020 Lessee, Operating Lease, Liability, Payments, Due Year Two 2021 Lessee, Operating Lease, Liability, Payments, Due Year Three 2022 Lessee, Operating Lease, Liability, Payments, Due Year Four 2023 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total lease payments Lessee, Operating Lease, Liability, Payments, Due Less: Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Operating lease liabilities Operating Lease, Liability Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2019 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total lease payments Operating Leases, Future Minimum Payments Due Retirement Benefits [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension benefits Pension Plan [Member] Other benefits Other Postretirement Benefits Plan [Member] Hawaiian Electric Industries, Inc. Parent Company [Member] Retirement benefits Defined Benefit Plan Disclosure [Line Items] Defined benefit plans Defined Benefit Plan [Abstract] Contributions made to defined benefit plans Defined Benefit Plan, Plan Assets, Contributions by Employer Contributions expected to be paid in current year Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year Expected payments for remainder of fiscal year Defined Benefit Plan, Expected Future Benefit Payment, Remainder of Fiscal Year Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of net prior service gain Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of net actuarial (gains) losses Defined Benefit Plan, Amortization of Gain (Loss) Net periodic pension/benefit cost (return) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Impact of PUC D&Os Defined Benefit Plan, Impact of Public Utilities Commission Decisions and Orders Represents the impact of Public Utilities Commission's decisions and orders on net periodic benefit cost. Net periodic pension/benefit cost (adjusted for impact of PUC D&Os) Defined Benefit Plan, Net Periodic Benefit Cost Adjusted for Impact of Public Utilities Commission Decisions and Orders Represents the total amount of net periodic benefit cost adjusted for impact of Public Utilities Commission's decisions and orders. Retirement benefits expense Pension and Other Postretirement Benefits Cost (Reversal of Cost) Number of years for which regulatory asset/liability for each utility will be amortized, beginning with respective utility's next rate case (in years) Defined Benefit Plan, Number of Years Regulatory Assets or Liability will be Amortized for Each Utility which Start from Respective Utilities Next Rate Case Represents the number of years for which regulatory asset/liability for each utilities will be amortized, beginning with the respective utility's next rate case. Defined contribution plan, expenses recognized Defined Contribution Plan, Cost Cash contributions by the employer to defined contribution plan Defined Contribution Plan, Contributions by Employer Represents the contributions made by the employer in defined contribution plan. Income Statement [Abstract] 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. Bank Banking Segment [Member] Represents information about the banking business segment of the company. Other Other Segments [Member] Revenues Revenues [Abstract] Total revenues Expenses Costs and Expenses [Abstract] 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 financial information Segment Reporting Disclosure [Text Block] Shareholders' equity Stockholders' Equity Note Disclosure [Text Block] Debt Disclosure [Abstract] Credit agreements and long-term debt Debt Disclosure [Text Block] Carrying amount and the total unpaid principal balance of impaired loans, with and without recorded allowance for loans losses Financing Receivable, Impaired [Line Items] Recorded investment: Impaired Financing Receivable, Recorded Investment [Abstract] With no related allowance recorded Impaired Financing Receivable, with No Related Allowance, Recorded Investment With an allowance recorded Impaired Financing Receivable, with Related Allowance, Recorded Investment Recorded investment Impaired Financing Receivable, Recorded Investment Unpaid principal balance: Impaired Financing Receivable, Unpaid Principal Balance [Abstract] With no related allowance recorded Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance With an allowance recorded Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance Unpaid principal balance Impaired Financing Receivable, Unpaid Principal Balance Related Allowance Impaired Financing Receivable, Related Allowance Average recorded investment: Impaired Financing Receivable, Average Recorded Investment [Abstract] With no related allowance recorded Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment With an allowance recorded Impaired Financing Receivable, with Related Allowance, Average Recorded Investment Average recorded investment Impaired Financing Receivable, Average Recorded Investment Interest income recognized: Impaired Financing Receivable, Interest Income, Accrual Method [Abstract] With no related allowance recorded Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method With an allowance recorded Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method Interest income recognized Impaired Financing Receivable, Interest Income, Accrual Method Proceeds from sale of available for sale securities Proceeds from Sale of Debt Securities, Available-for-sale AFS, gross realized gains Debt Securities, Available-for-sale, Unrealized Gain Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] AOCI AOCI Attributable to Parent [Member] Net unrealized gains (losses) on securities Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Unrealized gains (losses) on derivatives Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Retirement benefit plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract] AOCI Attributable to Parent, Net of Tax [Roll Forward] Beginning Balance Current period other comprehensive income (loss) Ending Balance Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Unfunded commitments to fund the company's LIHTC Qualified Affordable Housing Project Investments, Commitment Number of financial institutions Number of Financial Institutions Represents the number of financial institutions with which the entity entered into a revolving Non Collateralized credit agreement with a letter of credit sub-facility. Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Line of credit facility Line of Credit [Member] Credit agreement Debt Instrument [Line Items] Revolving noncollateralized credit facility with a letter of credit sub-facility Line of Credit Facility, Maximum Borrowing Capacity Revenue from Contract with Customer [Abstract] Disaggregation of revenue Disaggregation of Revenue [Table Text Block] Other Comprehensive Income (Loss), Net of Tax [Abstract] Other Comprehensive Income (Loss), Net of Tax [Abstract] Net unrealized gains (losses) on available-for-sale investment securities: Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax [Abstract] Net unrealized gains (losses) on available-for-sale investment securities arising during the period, net of (taxes) benefits of $(3,455) and $4,867, respectively Retirement benefit plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract] Adjustment for amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of (taxes) benefits of $(1,166) and $694, respectively Net unrealized gains (losses) on securities arising during the period, (taxes) benefits Amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, taxes (benefits) Share-based compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Real estate loans Real Estate Loan [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Loans receivable Loans and Leases Receivable, Gross Less: Deferred fees and discounts Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums Allowance for loan losses Loans and Leases Receivable, Allowance Net loans Loans and Leases Receivable, Net Amount Minimum benchmark percentage of loan to appraisal ratio 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. Fair Value, by Balance Sheet or Off Balance Sheet Grouping [Table] Fair Value, by Balance Sheet or Off Balance Sheet Grouping [Table] Fair value disclosures related to financial assets (as defined) and financial liabilities (as defined) whether contained in the entity's balance sheet or held off-balance sheet. Disclosures contained in this table include the carrying (reported) amount, the portion of the financial instrument (as defined) at fair value, portion at other than fair value, estimate of fair value, and the change in fair value during the period. Carrying or notional amount Reported Value Measurement [Member] Estimated fair value of financial instruments Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Financial assets Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Available-for-sale investment securities Held-to-maturity investment securities Stock in Federal Home Loan Bank Investment in Federal Home Loan Bank Stock, Fair Value Disclosure Mortgage-servicing rights Derivative assets Derivative Asset Financial liabilities Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Deposit liabilities Deposits, Fair Value Disclosure Short-term borrowings—other than bank Other Short-term Borrowings Other bank borrowings Other Bank Borrowings This element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. This item represents other bank borrowings as of the balance sheet date, including securities sold under agreements to repurchase and advances from the Federal Home Loan Bank. Long-term debt, net Long-term Debt, Fair Value Derivative liabilities Derivative Liability Short-term borrowings Short-term Debt, Fair Value Schedule of components of net periodic benefit cost for consolidated HEI Schedule of Net Benefit Costs [Table Text Block] Schedule of statements of income data Condensed Income Statement [Table Text Block] Schedule of statements of comprehensive income data Comprehensive Income (Loss) [Table Text Block] Schedule of balance sheets data Condensed Balance Sheet [Table Text Block] Schedule of the book value and aggregate fair value by major security type Debt Securities, Trading, and Equity Securities, FV-NI [Table Text Block] Schedule of contractual maturities of available-for-sale securities Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of components of loans receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Schedule of allowance for loan losses Schedule of Credit Losses for Financing Receivables, Current [Table Text Block] Schedule of credit risk profile by internally assigned grade for loans Financing Receivable Credit Quality Indicators [Table Text Block] Schedule of credit risk profile based on payment activity for loans Past Due Financing Receivables [Table Text Block] Schedule of credit risk profile based on nonaccrual loans, accruing loans 90 days or more past due Schedule of Financing Receivables, Non Accrual Status [Table Text Block] Schedule of the carrying amount and the total unpaid principal balance of impaired loans, with and without recorded allowance for loans losses Impaired Financing Receivables [Table Text Block] Schedule of loan modifications Troubled Debt Restructurings on Financing Receivables [Table Text Block] Schedule of amortized intangible assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of key assumptions used in estimating fair value Schedule of sensitivity analysis of fair value, transferor's interests in transferred financial assets Schedule of Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets [Table Text Block] Schedule of securities sold under agreements to repurchase Schedule of Assets Sold under Agreements to Repurchase, Other Borrowings [Table Text Block] Tabular disclosure of securities or other assets sold under repurchase agreements when this amount exceeds 10 percent of total assets. Disclosure may include the following: the type of securities or assets sold under agreements to repurchase, the carrying amount, market value (including accrued interest plus any cash or other assets on deposit. The information is segregated into securities maturing (1) overnight; (2) term up to 30 days; (3) term of 30 to 90 days; (4) term over 90 days; (5) demand. Schedule of notional and fair value of derivatives Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of derivative financial instruments Schedule of Derivative Instruments [Table Text Block] Schedule of derivative financial instruments and net gain or loss Derivative Instruments, Gain (Loss) [Table Text Block] Schedule of share-based compensation expense and related income tax benefit Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Schedule of common stock granted to a nonemployee director under the 2011 Director Plan Schedule of Share-based Compensation, Nonemployee Director Stock Award Plan, Activity [Table Text Block] Schedule of restricted stock units Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Schedule of Long-Term Incentive Plan (LTIP) linked to total return to shareholders Schedule of Share Based Compensation, Long term Incentive Plan Linked to Total Return to Shareholders [Table Text Block] Tabular disclosure of the number and weighted-average grant date fair value for long-term incentive plan awards that were outstanding at the beginning and end of the year, and the number that were granted, vested, or forfeited during the year. Schedule of Long-Term Incentive Program fair value awards granted Schedule of Long-Term Incentive Plan (LTIP) linked to other performance conditions Schedule of Share Based Compensation, Long term Incentive Plan Linked to Other Performance Conditions Activity [Table Text Block] Tabular disclosure of the number and weighted-average grant date fair value of shares that were outstanding at the beginning and end of the year, and the number of Long-Term Incentive Plan awards that were granted, vested, or forfeited during the year that were linked to other performance conditions. Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Equity and Incentive Plan 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] Long-term Incentive Plan 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. Number of additional shares authorized (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Shares available for future issuance (in shares) 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. Number of share issuable upon vesting and achievement of performance goals (in shares) 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. Shares available for future grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Fair value of vested stock Income tax benefit from compensation expense Unrecognized share based compensation Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted average period for recognition of unrecognized compensation cost (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Payment award, 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. Payment award, 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. Measurement period for total return to shareholders (in years) Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other than Option Period Used for Calculation of Total Return to Shareholders Represents the number of years used in the calculation of total return to shareholders. Award performance period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Period Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Period Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Electric energy sales - residential Electric Energy Sales, Residential [Member] Electric Energy Sales, Residential [Member] Electric energy sales - commercial Electric Energy Sales, Commercial [Member] Electric Energy Sales, Commercial [Member] Electric energy sales - large light and power Electric Energy Sales, Large Light And Power [Member] Electric Energy Sales, Large Light And Power [Member] Electric energy sales - other Electric Energy Sales, Other [Member] Electric Energy Sales, Other [Member] Bank fees Bank Fees [Member] Bank Fees [Member] Revenues from Other Sources Revenues From Other Sources [Member] Revenues From Other Sources [Member] Regulatory revenue Regulatory Revenue [Member] Regulatory Revenue [Member] Bank interest and dividend income Bank Interest And Dividend Income [Member] Bank Interest And Dividend Income [Member] Other bank noninterest income Other Bank Noninterest Income [Member] Other Bank Noninterest Income [Member] Other Other Revenue Sources [Member] Other Revenue Sources [Member] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Services/goods transferred at a point in time Transferred at Point in Time [Member] Services/goods transferred over time Transferred over Time [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Revenues from contracts with customers Total revenues Revenues Statements of Equity Increase (decrease) in stockholders' equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Other comprehensive income (loss), net of taxes Common stock dividends Dividends, Common Stock, Cash Common stock issuance expenses Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Statement of Financial Position [Abstract] Property, plant and equipment, accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Nonutility property, plant and equipment, accumulated depreciation Non-utilities, Property, Plant and Equipment, Accumulated Depreciation Non-utilities, Property, Plant and Equipment, Accumulated Depreciation Preferred stock, authorized shares (in shares) Preferred Stock, Shares Authorized Preferred stock, issued shares (in shares) Preferred Stock, Shares Issued Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, authorized shares (in shares) Common Stock, Shares Authorized Common stock, issued shares (in shares) Common Stock, Shares, Issued Common stock, outstanding shares (in shares) Common Stock, Shares, Outstanding Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Range of expected volatility for Peer Group, minimum rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Range of expected volatility for Peer Group, maximum rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Grant date fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award Fair Value Assumptions Grant Date Fair Value Represents the estimated fair value at grant date for nonvested equity-based awards on other than stock (or unit) option plans. Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Revenues from external customers Operating Segments [Member] Intersegment revenues (eliminations) Intersegment Eliminations [Member] Segment financial information Segment Reporting Information [Line Items] Total revenues Income (loss) before income taxes Income taxes (benefit) Total assets Recent accounting pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Document and Entity Information -- None. No documentation exists for this element. -- Entities [Table] Entities [Table] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business 2019 Annual incremental RAM adjusted revenues Public Utility, Annual Incremental Rate Adjustment Mechanism Adjusted Revenue Public Utility, Annual Incremental Rate Adjustment Mechanism Adjusted Revenue Annual change in accrued RBA balance as of December 31, 2018 (and associated revenue taxes) Public Utility, Increase (Decrease) In Accrued Earnings Sharing Credits To Be Refunded Public Utility, Increase (Decrease) In Accrued Earnings Sharing Credits To Be Refunded 2017 Tax Act Adjustment Public Utilities, Decoupling Filing, Tax Cuts And Jobs Act, Change In Tax Rate, Income Tax Expense (Benefit) Public Utilities, Decoupling Filing, Tax Cuts And Jobs Act, Change In Tax Rate, Income Tax Expense (Benefit) Performance Incentive Mechanism Public Utilities, Decoupling Filing, Performance Incentive Mechanism Public Utilities, Decoupling Filing, Performance Incentive Mechanism Net annual incremental amount to be collected under the tariffs Public Utility, Net Receivable Under Tariff Public Utility, Net Receivable Under Tariff Electric utility subsidiaries [Abstract] Electric utility subsidiaries [Abstract] Interim rate increases Public Utilities, Interim Rate Increase (Decrease), Amount Rate increase before tax act impact Public Utilities, Rate Increase Before Tax Act Impact, Amount Public Utilities, Rate Increase Before Tax Act Impact, Amount Tax act impact on rate, amount Public Utilities, Tax Act Impact On Rate, Amount Public Utilities, Tax Act Impact On Rate, Amount General rate increase, revenue, calculation assumptions, rate of return, ROACE 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 General rate increase, revenue, calculation assumptions, 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 Risk sharing percentage, ratepayer Public Utility, General Rate Increase, Risk Sharing Percentage, Ratepayer Public Utility, General Rate Increase, Risk Sharing Percentage, Ratepayer Risk sharing percentage, utility Public Utility, General Rate Increase, Risk Sharing Percentage, Utility Public Utility, General Rate Increase, Risk Sharing Percentage, Utility Maximum exposure cap Public Utility, General Rate Increase, Maximum Exposure Cap Public Utility, General Rate Increase, Maximum Exposure Cap Interim general rate increase granted Public Utilities, Interim General Rate Increase Public Utilities, Interim General Rate Increase Effective interest rate of return Public Utilities, Interim General Rate Increase, Effective Interest Rate Of Return Public Utilities, Interim General Rate Increase, Effective Interest Rate Of Return Stipulated ROACE rate Public Utilities, Stipulated Return On Average Common Equity Rate Public Utilities, Stipulated Return On Average Common Equity Rate Common equity capitalization rate Public Utilities, Interim General Rate Increase, Common Equity Capitalization Public Utilities, Interim General Rate Increase, Common Equity Capitalization Rate Base Public Utilities, Interim General Rate Increase, Rate Base Public Utilities, Interim General Rate Increase, Rate Base