Electric utility segment - Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Hawaiian Electric Company, Inc. and Subsidiaries
Revenue taxes
Electric Utility Revenue Taxes Included in Operating Revenues and in Taxes Other than Income Taxes Expense	$ 58	$ 74	$ 159	$ 203

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