Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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Period Type:	duration

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Credit agreements and changes in debt - Note Purchase Agreements (Details) - Senior Notes - USD ($)	Oct. 29, 2020	May 14, 2020
Unsecured Senior Notes Series 2020A
Debt Instrument [Line Items]
Aggregate principal amount		$ 80,000,000
Unsecured Senior Notes Series 2020A \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount		$ 50,000,000
Fixed coupon interest rate		3.31%
Unsecured Senior Notes Series 2020A \| HELCO
Debt Instrument [Line Items]
Aggregate principal amount		$ 10,000,000
Fixed coupon interest rate		3.96%
Unsecured Senior Notes Series 2020A \| Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000,000
Fixed coupon interest rate		3.31%
Unsecured Senior Notes Series 2020B
Debt Instrument [Line Items]
Aggregate principal amount		$ 60,000,000
Unsecured Senior Notes Series 2020B \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 15,000,000
Unsecured Senior Notes Series 2020B \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount		$ 40,000,000
Fixed coupon interest rate		3.31%
Unsecured Senior Notes Series 2020B \| HELCO \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 15,000,000
Fixed coupon interest rate	3.28%
Maturity date (from funding)	20 years
Unsecured Senior Notes Series 2020B \| Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000,000
Fixed coupon interest rate		3.96%
Unsecured Senior Notes Series 2020C
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000,000
Unsecured Senior Notes Series 2020C \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 40,000,000
Unsecured Senior Notes Series 2020C \| Hawaiian Electric (parent only)
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000,000
Fixed coupon interest rate		3.96%
Unsecured Senior Notes Series 2020C \| HELCO \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 15,000,000
Fixed coupon interest rate	3.51%
Maturity date (from funding)	30 years
Unsecured Senior Notes Series 2020C \| Maui Electric \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 25,000,000
Fixed coupon interest rate	3.51%
Maturity date (from funding)	30 years
Unsecured Senior Notes Series 2020D \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 30,000,000
Unsecured Senior Notes Series 2020D \| Hawaiian Electric (parent only) \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 30,000,000
Fixed coupon interest rate	3.28%
Maturity date (from funding)	20 years
Unsecured Senior Notes Series 2020E \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 30,000,000
Unsecured Senior Notes Series 2020E \| Hawaiian Electric (parent only) \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 30,000,000
Fixed coupon interest rate	3.51%
Maturity date (from funding)	30 years