Revenue taxes (Details) - HECO (Hawaiian Electric Company, Inc. and Subsidiaries, USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Hawaiian Electric Company, Inc. and Subsidiaries
Revenue taxes
Revenue taxes included in Operating revenues	$ 121	$ 100
Revenue taxes included as expense in Taxes, other than income taxes	$ 121	$ 100