Electric utility subsidiary - Consolidating statement of income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2015	Mar. 31, 2014
Operating expenses
Purchased power		$ 136,000	$ 165,000
Total expenses		568,356	694,535
Operating income		69,506	89,214
Other income (loss)
Allowance for equity funds used during construction	[1]	1,413	1,609
Interest and other charges
Allowance for borrowed funds used during construction		499	614
Income taxes		19,979	25,721
Net income	[1]	32,339	46,260
Preferred stock dividends of subsidiaries		473	473
Net income for common stock		31,866	45,787
Hawaiian Electric Company
Condensed Income Statements, Captions [Line Items]
Revenues		399,741	512,455
Operating expenses
Fuel oil		118,403	203,547
Purchased power		103,250	123,969
Other operation and maintenance		70,084	58,515
Depreciation		29,389	27,301
Taxes, other than income taxes		38,201	48,184
Total expenses		359,327	461,516
Operating income		40,414	50,939
Other income (loss)
Allowance for equity funds used during construction		1,123	1,472
Equity in earnings of subsidiaries		7,692	8,917
Interest expense and other charges, net		(11,238)	(10,487)
Interest and other charges
Allowance for borrowed funds used during construction		388	559
Income before income taxes		38,379	51,400
Income taxes		11,235	15,710
Net income		27,144	35,690
Net income attributable to Hawaiian Electric		27,144	35,690
Preferred stock dividends of Hawaiian Electric		270	270
Net income for common stock		26,874	35,420
HELCO
Condensed Income Statements, Captions [Line Items]
Revenues		88,055	104,931
Operating expenses
Fuel oil		23,385	31,500
Purchased power		21,893	29,491
Other operation and maintenance		16,399	14,047
Depreciation		9,313	8,975
Taxes, other than income taxes		8,384	9,763
Total expenses		79,374	93,776
Operating income		8,681	11,155
Other income (loss)
Allowance for equity funds used during construction		145	65
Interest expense and other charges, net		(2,680)	(2,748)
Interest and other charges
Allowance for borrowed funds used during construction		53	25
Income before income taxes		6,199	8,497
Income taxes		2,277	3,202
Net income		3,922	5,295
Preferred stock dividends of subsidiaries		134	134
Net income attributable to Hawaiian Electric		3,788	5,161
Net income for common stock		3,788	5,161
Maui Electric
Condensed Income Statements, Captions [Line Items]
Revenues		85,674	102,693
Operating expenses
Fuel oil		35,018	51,253
Purchased power		10,864	11,456
Other operation and maintenance		17,519	16,044
Depreciation		5,541	5,327
Taxes, other than income taxes		8,163	10,024
Total expenses		77,105	94,104
Operating income		8,569	8,589
Other income (loss)
Allowance for equity funds used during construction		145	72
Interest expense and other charges, net		(2,435)	(2,505)
Interest and other charges
Allowance for borrowed funds used during construction		58	30
Income before income taxes		6,337	6,186
Income taxes		2,338	2,335
Net income		3,999	3,851
Preferred stock dividends of subsidiaries		95	95
Net income attributable to Hawaiian Electric		3,904	3,756
Net income for common stock		3,904	3,756
Other subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues		0	0
Operating expenses
Other operation and maintenance		0	0
Total expenses		0	0
Operating income		0	0
Interest and other charges
Income before income taxes		0	0
Income taxes		0	0
Net income		0	0
Net income attributable to Hawaiian Electric		0	0
Net income for common stock		0	0
Consolidating adjustments
Condensed Income Statements, Captions [Line Items]
Revenues		(28)	(17)
Operating expenses
Operating income		(28)	(17)
Other income (loss)
Equity in earnings of subsidiaries		(7,692)	(8,917)
Interest expense and other charges, net		28	17
Interest and other charges
Income before income taxes		(7,692)	(8,917)
Income taxes		0	0
Net income		(7,692)	(8,917)
Net income attributable to Hawaiian Electric		(7,692)	(8,917)
Net income for common stock		(7,692)	(8,917)
HECO Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues		573,442	720,062
Operating expenses
Fuel oil		176,806	286,300
Purchased power		136,007	164,916
Other operation and maintenance		104,002	88,606
Depreciation		44,243	41,603
Taxes, other than income taxes		54,748	67,971
Total expenses		515,806	649,396
Operating income		57,636	70,666
Other income (loss)
Allowance for equity funds used during construction	[1]	1,413	1,609
Interest expense and other charges, net		(16,325)	(15,723)
Interest and other charges
Allowance for borrowed funds used during construction		499	614
Income before income taxes		43,223	57,166
Income taxes		15,850	21,247
Net income	[1]	27,373	35,919
Preferred stock dividends of subsidiaries		229	229
Net income attributable to Hawaiian Electric		27,144	35,690
Preferred stock dividends of Hawaiian Electric		270	270
Net income for common stock		$ 26,874	$ 35,420

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