Cash flows (Details) - HECO (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Supplemental disclosures of cash flow information
Income tax paid/(received)	$ (19)	$ 44
Hawaiian Electric Company, Inc. and Subsidiaries
Supplemental disclosures of cash flow information
Interest paid	43	42
Income tax paid/(received)	(27)	37
Supplemental disclosures of noncash activities
Electric utility property, plant and equipment - Unpaid invoices and other	$ 21	$ 13