Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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Credit agreements - Summary of Debt Instruments (Details) - USD ($) $ in Thousands			9 Months Ended
	Jul. 26, 2019	May 15, 2019	Sep. 30, 2019	Sep. 30, 2018	Oct. 10, 2019	Jul. 18, 2019	May 13, 2019
Debt Instrument [Line Items]
Aggregate principal amount, redeemed			$ 204,278	$ 1,867
HELCO
Debt Instrument [Line Items]
Aggregate principal amount, redeemed			70,000
Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount, redeemed			$ 10,000
Unsecured Notes \| Series 2019A
Debt Instrument [Line Items]
Aggregate principal amount, issued							$ 50,000
Fixed coupon interest rate							4.21%
Unsecured Notes \| Series 2019A \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount, issued							$ 30,000
Unsecured Notes \| Series 2019A \| HELCO
Debt Instrument [Line Items]
Aggregate principal amount, issued							10,000
Unsecured Notes \| Series 2019A \| Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount, issued							$ 10,000
Unsecured Notes \| 2004 Junior subordinated deferrable interest debentures redeemed
Debt Instrument [Line Items]
Aggregate principal amount, redeemed		$ 51,500
Fixed coupon interest rate		6.50%
Unsecured Notes \| 2004 Junior subordinated deferrable interest debentures redeemed \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount, redeemed		$ 31,500
Unsecured Notes \| 2004 Junior subordinated deferrable interest debentures redeemed \| HELCO
Debt Instrument [Line Items]
Aggregate principal amount, redeemed		10,000
Unsecured Notes \| 2004 Junior subordinated deferrable interest debentures redeemed \| Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount, redeemed		$ 10,000
Unsecured Notes \| Refunding Series 2019 Special Purpose Revenue Bonds
Debt Instrument [Line Items]
Aggregate principal amount, issued						$ 150,000
Fixed coupon interest rate						3.20%
Unsecured Notes \| Refunding Series 2019 Special Purpose Revenue Bonds \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount, issued						$ 90,000
Unsecured Notes \| Refunding Series 2019 Special Purpose Revenue Bonds \| HELCO
Debt Instrument [Line Items]
Aggregate principal amount, issued						$ 60,000
Unsecured Notes \| Series 2009 Special Purpose Revenue Bonds Redeemed
Debt Instrument [Line Items]
Aggregate principal amount, redeemed	$ 150,000
Fixed coupon interest rate	6.50%
Unsecured Notes \| Series 2009 Special Purpose Revenue Bonds Redeemed \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount, redeemed	$ 90,000
Unsecured Notes \| Series 2009 Special Purpose Revenue Bonds Redeemed \| HELCO
Debt Instrument [Line Items]
Aggregate principal amount, redeemed	$ 60,000
Unsecured Notes \| Series 2019 Special Purpose Revenue Bonds \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount, issued					$ 80,000
Fixed coupon interest rate					3.50%
Unsecured Notes \| Series 2019 Special Purpose Revenue Bonds \| Hawaiian Electric (parent only) \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount, issued					$ 70,000
Unsecured Notes \| Series 2019 Special Purpose Revenue Bonds \| HELCO \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount, issued					2,500
Unsecured Notes \| Series 2019 Special Purpose Revenue Bonds \| Maui Electric \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount, issued					$ 7,500