Revenue taxes (Details) - HECO (Hawaiian Electric Company, Inc. and Subsidiaries, USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011
Hawaiian Electric Company, Inc. and Subsidiaries
Revenue taxes
Revenue taxes included in Operating revenues	$ 140	$ 121
Revenue taxes included as expense in Taxes, other than income taxes	$ 140	$ 121

Discloses the amount included as operating expenses for the period related to revenues taxes, which is included in Taxes, other than income taxes.

No definition available.

Name:	he_OperatingExpensesRevenuesTaxes
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration