Electric utility subsidiary - Consolidating statement of comprehensive income (loss) (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Statement of Income Captions [Line Items]
Net income for common stock	$ 35,018	$ 41,281	$ 66,884	$ 87,068
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	5,780	2,873	11,239	5,686
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	(5,272)	(2,575)	(10,183)	(5,085)
Other comprehensive income (loss), net of taxes	(3,127)	2,900	931	4,067
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	31,891	44,181	67,815	91,135
Hawaiian Electric Company
Condensed Statement of Income Captions [Line Items]
Net income for common stock	32,841	34,230	59,715	69,650
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	5,257	2,588	10,190	5,107
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	(5,272)	(2,575)	(10,183)	(5,085)
Other comprehensive income (loss), net of taxes	(15)	13	7	22
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	32,826	34,243	59,722	69,672
HELCO
Condensed Statement of Income Captions [Line Items]
Net income for common stock	4,484	4,846	8,272	10,007
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	713	292	1,364	636
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	(716)	(292)	(1,367)	(636)
Other comprehensive income (loss), net of taxes	(3)	0	(3)	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	4,481	4,846	8,269	10,007
Maui Electric
Condensed Statement of Income Captions [Line Items]
Net income for common stock	5,140	5,013	9,044	8,769
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	652	292	1,252	545
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	(655)	(292)	(1,255)	(545)
Other comprehensive income (loss), net of taxes	(3)	0	(3)	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	5,137	5,013	9,041	8,769
Other subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income for common stock	0	0	0	0
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	0	0	0	0
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	0	0	0	0
Other comprehensive income (loss), net of taxes	0	0	0	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	0	0	0	0
Consolidating adjustments
Condensed Statement of Income Captions [Line Items]
Net income for common stock	(9,624)	(9,859)	(17,316)	(18,776)
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	(1,365)	(584)	(2,616)	(1,181)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	1,371	584	2,622	1,181
Other comprehensive income (loss), net of taxes	6	0	6	0
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	(9,618)	(9,859)	(17,310)	(18,776)
HECO Consolidated
Condensed Statement of Income Captions [Line Items]
Net income for common stock	32,841	34,230	59,715	69,650
Retirement benefit plans:
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $3,349, $1,647, $6,490 and $3,252 for the respective periods	5,257	2,588	10,190	5,107
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,359, $1,641, $6,486 and $3,239 for the respective periods	(5,272)	(2,575)	(10,183)	(5,085)
Other comprehensive income (loss), net of taxes	(15)	13	7	22
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	$ 32,826	$ 34,243	$ 59,722	$ 69,672