Electric utility segment Consolidating Statement of Income (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	May. 31, 2013	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Expenses
Total expenses										$ 2,910,618	$ 2,923,051		$ 3,090,799
Total operating income		$ 67,241	$ 91,102	$ 82,275	$ 88,306	$ 78,349	$ 88,038	$ 80,207	$ 68,825	328,924	315,419		284,196
Allowance for equity funds used during construction										6,771	5,561	[1]	7,007	[1]
Allowance for borrowed funds used during construction										2,579	2,246		4,355
Income before income taxes										261,922	247,747		217,407
Income taxes										91,712	84,341		76,859
Net income		33,630	48,286	41,894	46,400	39,486	48,707	41,061	34,152	170,210	163,406	[1]	140,548	[1]
Preferred stock dividends of subsidiaries										1,890	1,890		1,890
Net income for common stock		33,157	47,815	41,421	45,927	39,013	48,236	40,588	33,679	168,320	161,516		138,658
HECO
Revenues										2,142,245	2,124,174		2,228,233
Expenses
Fuel oil										821,246	851,365		945,246
Purchased power										537,821	527,839		540,802
Other operation and maintenance										283,532	283,768		266,208
Depreciation										109,204	99,738		90,783
Taxes, other than income taxes										201,426	200,962		209,943
Impairment of utility assets											0		29,000
Total expenses										1,953,229	1,963,672		2,081,982
Total operating income										189,016	160,502		146,251
Allowance for equity funds used during construction										6,085	4,495		5,735
Equity in earnings of subsidiaries										40,964	41,410		28,836
Interest expense and other charges, net										(44,041)	(39,107)		(40,842)
Allowance for borrowed funds used during construction										2,306	1,814		3,642
Income before income taxes										194,330	169,114		143,622
Income taxes										55,609	45,105		43,266
Net income										138,721	124,009		100,356
Net income attributable to Hawaiian Electric										138,721	124,009		100,356
Preferred stock dividends of Hawaiian Electric										1,080	1,080		1,080
Net income for common stock										137,641	122,929		99,276
HELCO
Revenues										422,200	431,517		441,013
Expenses
Fuel oil										117,215	125,516		116,866
Purchased power										123,226	128,368		145,386
Other operation and maintenance										65,471	61,418		60,447
Depreciation										35,904	34,188		33,337
Taxes, other than income taxes										39,521	40,092		41,370
Impairment of utility assets											0		5,500
Total expenses										381,337	389,582		402,906
Total operating income										40,863	41,935		38,107
Allowance for equity funds used during construction										472	643		585
Interest expense and other charges, net										(11,030)	(11,341)		(12,066)
Allowance for borrowed funds used during construction										182	263		235
Income before income taxes										30,487	31,500		26,861
Income taxes										11,264	10,830		10,115
Net income										19,223	20,670		16,746
Preferred stock dividends of subsidiaries										534	534		534
Net income attributable to Hawaiian Electric										18,689	20,136		16,212
Net income for common stock										18,689	20,136		16,212
MECO
Revenues	$ 5,300									422,965	424,603		440,270
Expenses
Fuel oil										193,224	208,671		235,307
Purchased power										60,961	54,474		38,052
Other operation and maintenance										61,609	58,081		70,771
Depreciation										21,279	20,099		20,378
Taxes, other than income taxes										39,916	40,077		41,528
Impairment of utility assets											0		5,500
Total expenses										376,989	381,402		411,536
Total operating income										45,976	43,201		28,734
Allowance for equity funds used during construction										214	423		687
Interest expense and other charges, net										(9,773)	(8,953)		(9,224)
Allowance for borrowed funds used during construction										91	169		478
Income before income taxes										36,508	34,840		20,675
Income taxes										13,852	13,182		7,667
Net income										22,656	21,658		13,008
Preferred stock dividends of subsidiaries										381	381		381
Net income attributable to Hawaiian Electric										22,275	21,277		12,627
Net income for common stock										22,275	21,277		12,627
Other subsidiaries
Revenues										0
Expenses
Other operation and maintenance										0	3		3
Total expenses										0	3		3
Total operating income										0	(3)		(3)
Income before income taxes										0	(3)		(3)
Income taxes										0
Net income										0	(3)		(3)
Net income attributable to Hawaiian Electric										0	(3)		(3)
Net income for common stock										0	(3)		(3)
Consolidating adjustments
Revenues										(87)	(122)		(77)
Expenses
Total operating income										(87)	(122)		(77)
Equity in earnings of subsidiaries										(40,964)	(41,410)		(28,836)
Interest expense and other charges, net										87	122		77
Income before income taxes										(40,964)	(41,410)		(28,836)
Income taxes										0
Net income										(40,964)	(41,410)		(28,836)
Net income attributable to Hawaiian Electric										(40,964)	(41,410)		(28,836)
Net income for common stock										(40,964)	(41,410)		(28,836)
HECO Consolidated
Revenues										2,987,323	2,980,172		3,109,439
Expenses
Fuel oil										1,131,685	1,185,552		1,297,419
Purchased power										722,008	710,681		724,240
Other operation and maintenance										410,612	403,270		397,429
Depreciation										166,387	154,025		144,498
Taxes, other than income taxes										280,863	281,131		292,841
Impairment of utility assets										0	0		40,000
Total expenses										2,711,555	2,734,659		2,896,427
Total operating income		58,878	76,156	70,068	70,666	65,564	69,853	58,975	51,121	275,768	245,513		213,012
Allowance for equity funds used during construction										6,771	5,561	[1]	7,007	[1]
Interest expense and other charges, net										(64,757)	(59,279)		(62,055)
Allowance for borrowed funds used during construction										2,579	2,246		4,355
Income before income taxes										220,361	194,041		162,319
Income taxes										80,725	69,117		61,048
Net income		29,611	39,377	34,729	35,919	32,489	38,315	29,192	24,928	139,636	124,924	[1]	101,271	[1]
Preferred stock dividends of subsidiaries										915	915		915
Net income attributable to Hawaiian Electric										138,721	124,009		100,356
Preferred stock dividends of Hawaiian Electric										1,080	1,080		1,080
Net income for common stock		$ 29,112	$ 38,879	$ 34,230	$ 35,420	$ 31,990	$ 37,817	$ 28,693	$ 24,429	$ 137,641	$ 122,929		$ 99,276

[1] As restated - See Note 1, “Summary of significant accounting policies - Revision and restatements of previously issued financial statements.”