Fair value measurements (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Commercial loans \| Third party appraisal
Significant unobservable inputs
Loans	$ 97
Significant unobservable inputs
Fair value of business assets (as a percent)	15.00%
Commercial loans \| Present value of cash flows
Significant unobservable inputs
Loans	2,600
Significant unobservable inputs
Present value of expected future cash flows based on anticipated debt restructuring (as a percent)	66.00%
Discount rate (as a percent)	4.50%
Commercial loans \| Third party appraisal
Significant unobservable inputs
Loans	1,599
Significant unobservable inputs
Insurance proceeds (as a percent)	100.00%
Commercial loans \| Third party appraisal
Significant unobservable inputs
Loans	1,506
Significant unobservable inputs
Present value of expected cash flows of property rental (as a percent)	61.00%
Residential loans \| Third party appraisal
Significant unobservable inputs
Loans	27,060
Significant unobservable inputs
Property sales (as a percent)	65.00%
Home equity line of credit \| Third party appraisal
Significant unobservable inputs
Loans	$ 659
Significant unobservable inputs
Property sales (as a percent)	42.00%

Name:	he_FairValueInputsAbstract
Namespace Prefix:	he_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	he_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix:	he_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the discount rate, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsDiscountRate
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the rate of fair value of business assets are measured, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsFairValueOfBusinessAssets
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the rate of insurance proceeds, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsInsuranceProceeds
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the present value of expected cash flows of the property rental, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsPresentValueOfExpectedCashFlowsOfThePropertyRental
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the rate of present value of expected future cash flows based on anticipated debt restructuring, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsPresentValueOfExpectedFutureCashFlowsBasedOnAnticipatedDebtRestructuring
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents property sales, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsPropertySales
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents loan receivable as presented on the statement of financial position which may include mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts, or any other loans which are due the Company as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Loan

-Topic 310

-SubTopic 10

-URI http://asc.fasb.org/extlink&oid=6517073

+ Details

Name:	us-gaap_LoansReceivableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant