Basis of presentation - Revision of previously issued financial statements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization	$ 12,080	$ 5,081
Increase in deferred income taxes	2,723	50,296
Share-based compensation expense	4,780	7,200
Decrease in accounts, interest and dividends payable	(34,171)	(51,199)
Change in other assets and liabilities	(38,033)	(56,326)
Net cash provided by operating activities	221,252	197,310
Capital expenditures	(276,186)	(260,616)
Other	4,084	674
Net cash used in investing activities	(502,997)	(400,892)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		15,000
Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization	9,827	4,289
Increase in deferred income taxes	58,211	67,392
Change in other assets and liabilities	(20,804)	(41,969)
Net cash provided by operating activities	201,586	170,167
Capital expenditures	(265,521)	(253,718)
Other	778	713
Net cash used in investing activities	(230,116)	(231,265)
Decrease in accounts payable	$ (40,375)	(53,280)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		15,000
Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		5,454
Increase in deferred income taxes		49,270
Share-based compensation expense		0
Decrease in accounts, interest and dividends payable		(75,812)
Change in other assets and liabilities		(47,760)
Net cash provided by operating activities		173,410
Capital expenditures		(236,003)
Other		(39)
Net cash used in investing activities		(376,992)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		40,000
Scenario, Previously Reported | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		4,662
Change in other assets and liabilities		(41,629)
Net cash provided by operating activities		146,267
Capital expenditures		(229,105)
Other		0
Net cash used in investing activities		(207,365)
Decrease in accounts payable		(77,893)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		40,000
Difference
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		(373)
Increase in deferred income taxes		1,026
Share-based compensation expense		7,200
Decrease in accounts, interest and dividends payable		24,613
Change in other assets and liabilities		(8,566)
Net cash provided by operating activities		23,900
Capital expenditures		(24,613)
Other		713
Net cash used in investing activities		(23,900)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		(25,000)
Difference | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		(373)
Change in other assets and liabilities		(340)
Net cash provided by operating activities		23,900
Capital expenditures		(24,613)
Other		713
Net cash used in investing activities		(23,900)
Decrease in accounts payable		24,613
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		$ (25,000)