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Electric utility segment - Unconsolidated Variable Interest Entities (Details) | 1 Months Ended | 12 Months Ended
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Mar. 31, 2004 USD ($) security | Dec. 31, 2017 USD ($) agreement entity
Variable Interest Entity [Line Items] |  |
Number of power purchase agreements (PPAs) | agreement |  | 5
Hawaiian Electric Company, Inc (HECO) |  |
Variable Interest Entity [Line Items] |  |
Number of power purchase agreements (PPAs) | agreement |  | 5
Number of entities owning wind farms not required to be consolidated as VIE's | entity |  | 2
Minimum potential number of IPP entities consolidated into company in the future | entity |  | 1
Variable Interest Entity, Not Primary Beneficiary |  |
Variable Interest Entity [Line Items] |  |
Investment in 2004 Debentures |  | $ 51,500,000
Interest income |  | 3,400,000
Variable Interest Entity, Not Primary Beneficiary | Hawaiian Electric Company, Inc (HECO) |  |
Variable Interest Entity [Line Items] |  |
Principal amount of 2004 Debentures | $ 31,500,000.0 |
Variable Interest Entity, Not Primary Beneficiary | Hawaii Electric Light Company, Inc. (HELCO) |  |
Variable Interest Entity [Line Items] |  |
Principal amount of 2004 Debentures | $ 10,000,000 |
Variable Interest Entity, Not Primary Beneficiary | 2004 Trust Preferred Securities | Hawaiian Electric Company, Inc (HECO) |  |
Variable Interest Entity [Line Items] |  |
Number of 2004 Trust Preferred Securities issued | security | 2,000,000 |
Dividend rate on 2004 Trust Preferred Securities | 6.50% |
Aggregate Liquidation preference | $ 50,000,000 |
Balance of Trust Securities |  | 50,000,000
Dividend distributions on Trust Preferred Securities |  | 3,300,000
Variable Interest Entity, Not Primary Beneficiary | Trust Common Securities | Hawaiian Electric Company, Inc (HECO) |  |
Variable Interest Entity [Line Items] |  |
Aggregate Liquidation preference | $ 1,500,000.0 |
Balance of Trust Securities |  | 1,500,000
Common dividend |  | $ 100,000

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- Definition Preferred securities that embody an unconditional obligation requiring the issuer to redeem the securities by transferring the assets at a specified or determinable date (or dates) or upon an event that is certain to occur, that are issued by a trust to outside investors where the trust uses the proceeds of the issuance of those securities to purchase an equivalent amount of junior subordinated debentures or other loans having stated maturities. + References No definition available. + Details
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- Definition Adjustment to net income reflecting the dividends paid to the holders of Trust Common Securities. + References No definition available. + Details
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- Definition 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. + References No definition available. + Details
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- Definition Number of entities owning wind farms not required to be consolidated as VIEs. + References No definition available. + Details
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- Definition Represents the number of firm power purchase agreements entered into, by the company. + References No definition available. + Details
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- Definition The value of liquidation preference (or restrictions) of securities that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share. + References No definition available. + Details
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- Definition The percentage rate used to calculate dividend payments on Trust Preferred Securities. + References No definition available. + Details
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- Definition Total number of Trust Preferred Securities issued during the period. + References No definition available. + Details
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- Definition The amount of interest incurred to a trust which has issued trust-preferred securities. In order to issue trust preferred securities, a sponsor forms a trust by investing a nominal amount of cash to purchase all of the voting common stock of the trust. The trust issues nonvoting, mandatorily redeemable preferred securities to outside investors in exchange for cash. The proceeds received from the issuance of the preferred securities, together with the cash received for issuing the common stock to the sponsor, is then loaned to the sponsor in exchange for a note which has the same terms as the trust preferred securities. Trust preferred securities possesses characteristics of both equity and debt issues and are generally issued by bank holding companies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 480 -SubTopic 10 -Section 55 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6924035&loc=d3e22274-110880 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(9)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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