Electric utility subsidiary - Consolidating statement of income (unaudited) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating expenses
Purchased power	$ 149,000	$ 188,000	$ 285,000	$ 353,000
Total expenses	551,182	715,474	1,119,538	1,410,009
Operating income	72,730	83,183	142,236	172,397
Other income (loss)
Allowance for equity funds used during construction	1,896	1,387	3,309	2,996
Interest and other charges
Allowance for borrowed funds used during construction	682	523	1,181	1,137
Income taxes	20,911	23,317	40,890	49,038
Net income	35,491	41,754	67,830	88,014
Preferred stock dividends of subsidiaries	473	473	946	946
Net income for common stock	35,018	41,281	66,884	87,068
Hawaiian Electric Company
Condensed Income Statements, Captions [Line Items]
Revenues	391,007	530,991	790,748	1,043,446
Operating expenses
Fuel oil	104,278	195,549	222,681	399,096
Purchased power	107,370	140,805	210,620	264,774
Other operation and maintenance	66,428	68,992	136,512	127,507
Depreciation	29,389	27,300	58,778	54,601
Taxes, other than income taxes	37,479	49,949	75,680	98,133
Total expenses	344,944	482,595	704,271	944,111
Operating income	46,063	48,396	86,477	99,335
Other income (loss)
Allowance for equity funds used during construction	1,581	1,417	2,704	2,889
Equity in earnings of subsidiaries	9,624	9,859	17,316	18,776
Interest and other charges
Interest expense and other charges, net	(11,290)	(11,553)	(22,528)	(22,040)
Allowance for borrowed funds used during construction	564	535	952	1,094
Income before income taxes	46,542	48,654	84,921	100,054
Income taxes	13,431	14,154	24,666	29,864
Net income	33,111	34,500	60,255	70,190
Net income attributable to Hawaiian Electric	33,111	34,500	60,255	70,190
Preferred stock dividends of Hawaiian Electric	270	270	540	540
Net income for common stock	32,841	34,230	59,715	69,650
HELCO
Condensed Income Statements, Captions [Line Items]
Revenues	83,732	103,544	171,787	208,475
Operating expenses
Fuel oil	16,241	31,179	39,626	62,679
Purchased power	24,555	28,170	46,448	57,661
Other operation and maintenance	16,158	14,817	32,557	28,864
Depreciation	9,312	8,976	18,625	17,951
Taxes, other than income taxes	7,944	9,757	16,328	19,520
Total expenses	74,210	92,899	153,584	186,675
Operating income	9,522	10,645	18,203	21,800
Other income (loss)
Allowance for equity funds used during construction	165	121	310	186
Interest and other charges
Interest expense and other charges, net	(2,592)	(2,852)	(5,272)	(5,600)
Allowance for borrowed funds used during construction	58	47	111	72
Income before income taxes	7,153	7,961	13,352	16,458
Income taxes	2,536	2,982	4,813	6,184
Net income	4,617	4,979	8,539	10,274
Preferred stock dividends of subsidiaries	133	133	267	267
Net income attributable to Hawaiian Electric	4,484	4,846	8,272	10,007
Net income for common stock	4,484	4,846	8,272	10,007
Maui Electric
Condensed Income Statements, Captions [Line Items]
Revenues	83,442	103,916	169,116	206,609
Operating expenses
Fuel oil	25,712	43,529	60,730	94,782
Purchased power	17,359	19,348	28,223	30,804
Other operation and maintenance	16,278	14,755	33,797	30,799
Depreciation	5,540	5,317	11,081	10,644
Taxes, other than income taxes	7,959	9,918	16,122	19,942
Total expenses	72,848	92,867	149,953	186,971
Operating income	10,594	11,049	19,163	19,638
Other income (loss)
Allowance for equity funds used during construction	150	(151)	295	(79)
Interest and other charges
Interest expense and other charges, net	(2,424)	(2,469)	(4,859)	(4,974)
Allowance for borrowed funds used during construction	60	(59)	118	(29)
Income before income taxes	8,380	8,370	14,717	14,556
Income taxes	3,144	3,261	5,482	5,596
Net income	5,236	5,109	9,235	8,960
Preferred stock dividends of subsidiaries	96	96	191	191
Net income attributable to Hawaiian Electric	5,140	5,013	9,044	8,769
Net income for common stock	5,140	5,013	9,044	8,769
Other subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	0	0	0	0
Operating expenses
Other operation and maintenance	0	0	0	0
Total expenses	0	0	0	0
Operating income	0	0	0	0
Interest and other charges
Income before income taxes	0	0	0	0
Income taxes	0	0	0	0
Net income	0	0	0	0
Net income attributable to Hawaiian Electric	0	0	0	0
Net income for common stock	0	0	0	0
Consolidating adjustments
Condensed Income Statements, Captions [Line Items]
Revenues	(18)	(22)	(46)	(39)
Operating expenses
Operating income	(18)	(22)	(46)	(39)
Other income (loss)
Equity in earnings of subsidiaries	(9,624)	(9,859)	(17,316)	(18,776)
Interest and other charges
Interest expense and other charges, net	18	22	46	39
Income before income taxes	(9,624)	(9,859)	(17,316)	(18,776)
Income taxes	0	0	0	0
Net income	(9,624)	(9,859)	(17,316)	(18,776)
Net income attributable to Hawaiian Electric	(9,624)	(9,859)	(17,316)	(18,776)
Net income for common stock	(9,624)	(9,859)	(17,316)	(18,776)
HECO Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	558,163	738,429	1,131,605	1,458,491
Operating expenses
Fuel oil	146,231	270,257	323,037	556,557
Purchased power	149,284	188,323	285,291	353,239
Other operation and maintenance	98,864	98,564	202,866	187,170
Depreciation	44,241	41,593	88,484	83,196
Taxes, other than income taxes	53,382	69,624	108,130	137,595
Total expenses	492,002	668,361	1,007,808	1,317,757
Operating income	66,161	70,068	123,797	140,734
Other income (loss)
Allowance for equity funds used during construction	1,896	1,387	3,309	2,996
Interest and other charges
Interest expense and other charges, net	(16,288)	(16,852)	(32,613)	(32,575)
Allowance for borrowed funds used during construction	682	523	1,181	1,137
Income before income taxes	52,451	55,126	95,674	112,292
Income taxes	19,111	20,397	34,961	41,644
Net income	33,340	34,729	60,713	70,648
Preferred stock dividends of subsidiaries	229	229	458	458
Net income attributable to Hawaiian Electric	33,111	34,500	60,255	70,190
Preferred stock dividends of Hawaiian Electric	270	270	540	540
Net income for common stock	$ 32,841	$ 34,230	$ 59,715	$ 69,650