Cash flows (Details) - HECO (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Supplemental disclosures of cash flow information
Income taxes paid/(refunded)	$ 2	$ 0
Supplemental disclosures of noncash activities
Additions to electric utility property, plant and equipment - Unpaid invoices and other	17	27
Hawaiian Electric Company, Inc. and Subsidiaries
Supplemental disclosures of cash flow information
Interest paid	43	40
Income taxes paid/(refunded)	(26)	2
Supplemental disclosures of noncash activities
Additions to electric utility property, plant and equipment - Unpaid invoices and other	$ 17	$ 27