Cash flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Supplemental disclosures of cash flow information
Interest paid	$ 61	$ 64
Income taxes paid	62	31
Income taxes refunded	55	24
Supplemental disclosures of noncash activities
Real estate acquired in settlement of loans (investing)	0	2
Real estate transferred from property, plant and equipment to other assets held-for-sale (investing)	5	0
Obligations to fund low income housing investments (operating)	1	6
Additions to electric utility property, plant and equipment - unpaid invoices and accruals (investing), as revised for the nine months ended September 30, 2014 (1)	1	15
Hawaiian Electric Company, Inc. and Subsidiaries
Supplemental disclosures of cash flow information
Interest paid	43	44
Income taxes paid	13	6
Income taxes refunded	$ 12	$ 8