Basis of presentation - Restatement and revision of previously filed financial statements (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization	[1]	$ 4,792	$ 4,014
Increase (decrease) in deferred income taxes	[1]	(4,463)	44,494
Share-based compensation expense	[1]	3,769	5,206
Increase (decrease) in accounts, interest and dividends payable	[1]	8,504	(40,230)
Change in other assets and liabilities	[1]	(24,455)	(38,540)
Net cash provided by operating activities	[1]	168,372	70,307
Capital expenditures	[1]	(206,816)	(173,866)
Other	[1]	3,819	485
Net cash used in investing activities	[1]	(291,775)	(296,214)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		(12,000)	3,000
Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization	[1]	3,220	3,597
Increase (decrease) in deferred income taxes	[1]	33,320	45,386
Change in other assets and liabilities	[1]	(14,085)	(26,759)
Net cash provided by operating activities	[1]	127,676	49,244
Capital expenditures	[1]	(199,143)	(170,347)
Other		511	501
Net cash used in investing activities	[1]	(179,543)	(156,637)
Decrease in accounts payable	[1]	(4,371)	(38,693)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		(12,000)	3,000
Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		4,320
Increase (decrease) in deferred income taxes		22,980	28,570
Share-based compensation expense		0	0
Increase (decrease) in accounts, interest and dividends payable		(56,076)	(64,843)
Change in other assets and liabilities		(47,146)	(16,909)
Net cash provided by operating activities		104,303	46,195
Capital expenditures		(142,236)	(149,253)
Other		3,308	(16)
Net cash used in investing activities		(227,706)	(272,102)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		53,000	28,000
Scenario, Previously Reported | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		2,748
Change in other assets and liabilities		(13,102)	(26,258)
Net cash provided by operating activities		63,607	25,132
Capital expenditures		(134,563)	(145,734)
Other		0	0
Net cash used in investing activities		(115,474)	(132,525)
Decrease in accounts payable		(68,951)	(63,306)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		53,000	28,000
Difference
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		472
Increase (decrease) in deferred income taxes		(27,443)	15,924
Share-based compensation expense		3,769	5,206
Increase (decrease) in accounts, interest and dividends payable		64,580	24,613
Change in other assets and liabilities		22,691	(21,631)
Net cash provided by operating activities		64,069	24,112
Capital expenditures		(64,580)	(24,613)
Other		511	501
Net cash used in investing activities		(64,069)	(24,112)
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		(65,000)	(25,000)
Difference | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other amortization		472
Change in other assets and liabilities		(983)	(501)
Net cash provided by operating activities		64,069	24,112
Capital expenditures		(64,580)	(24,613)
Other		511	501
Net cash used in investing activities		(64,069)	(24,112)
Decrease in accounts payable		64,580	24,613
Additions to electric utility property, plant and equipment - unpaid invoices and other (investing)/______________________________ (in millions)		$ (65,000)	$ (25,000)

[1] As restated - See Note 1, “Basis of presentation - Restatement of previously issued financial statements.”