Electric utility subsidiary - Taxes (Details) (Hawaiian Electric Company, Inc. and Subsidiaries, USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Hawaiian Electric Company, Inc. and Subsidiaries
Revenue taxes
Electric Utility Revenue Taxes Included in Operating Revenues and in Taxes Other than Income Taxes Expense	$ 51	$ 65

Represents the utility revenue taxes included in operating revenues and in taxes, other than income taxes expense.

No definition available.

Name:	he_ElectricUtilityRevenueTaxesIncludedInOperatingRevenuesAndInTaxesOtherThanIncomeTaxesExpense
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration