Bank segment - Troubled debt restructuring - narrative (Details) (Land loans)	3 Months Ended
Mar. 31, 2015
Troubled debt restructurings
Period of interest-only monthly payment term loan	3 years
Maximum
Troubled debt restructurings
Extension of maturity date	5 years

Represents the period of interest-only monthly payment term loan under the troubled debt restructuring plan.

No definition available.

Name:	he_FinancingReceivableModificationsPeriodOfInterestOnlyMonthlyPaymentTermLoan
Namespace Prefix:	he_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration