Significant group concentrations of credit risk (Details)	12 Months Ended
Dec. 31, 2011
Significant group concentrations of credit risk
Percentage of benchmark loan to appraisal ratio in excess of which mortgage insurance is required	80.00%

Represents the minimum benchmark percentage of loan to appraisal ratio which mortgage insurance is required as per the policy of American Savings Bank.

No definition available.

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