Electric utility subsidiary - Consolidating financial statements (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income for common stock	$ 47,815	$ 48,236	$ 135,163	$ 122,503
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 for the respective periods	2,829	5,789	8,515	17,490
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $1,619, $3,284, $4,858 and $9,852 for the respective periods	(2,542)	(5,156)	(7,627)	(15,468)
Other comprehensive income (loss), net of taxes	(1,311)	(897)	2,756	(9,263)
Comprehensive income	46,504	47,339	137,919	113,240
Hawaiian Electric Company
Net income for common stock	38,879	37,817	108,529	90,939
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 for the respective periods	2,552	5,173	7,659	15,520
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $1,619, $3,284, $4,858 and $9,852 for the respective periods	(2,542)	(5,156)	(7,627)	(15,468)
Other comprehensive income (loss), net of taxes	10	17	32	52
Comprehensive income	38,889	37,834	108,561	90,991
HELCO
Net income for common stock	3,301	5,444	13,308	14,744
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 for the respective periods	317	720	953	2,160
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $1,619, $3,284, $4,858 and $9,852 for the respective periods	(319)	(721)	(955)	(2,162)
Other comprehensive income (loss), net of taxes	(2)	(1)	(2)	(2)
Comprehensive income	3,299	5,443	13,306	14,742
Maui Electric
Net income for common stock	6,499	5,351	15,268	15,704
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 for the respective periods	272	639	817	1,918
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $1,619, $3,284, $4,858 and $9,852 for the respective periods	(272)	(639)	(817)	(1,918)
Other comprehensive income (loss), net of taxes	0	0	0	0
Comprehensive income	6,499	5,351	15,268	15,704
Other subsidiaries
Net income for common stock	0	(1)	0	(2)
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 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 $1,619, $3,284, $4,858 and $9,852 for the respective periods	0	0	0	0
Other comprehensive income (loss), net of taxes	0	0	0	0
Comprehensive income	0	(1)	0	(2)
Consolidating adjustments
Net income for common stock	(9,800)	(10,794)	(28,576)	(30,446)
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 for the respective periods	(589)	(1,359)	(1,770)	(4,078)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $1,619, $3,284, $4,858 and $9,852 for the respective periods	591	1,360	1,772	4,080
Other comprehensive income (loss), net of taxes	2	1	2	2
Comprehensive income	(9,798)	(10,793)	(28,574)	(30,444)
HECO Consolidated
Net income for common stock	38,879	37,817	108,529	90,939
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,626, $3,295, $4,878 and $9,885 for the respective periods	2,552	5,173	7,659	15,520
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $1,619, $3,284, $4,858 and $9,852 for the respective periods	(2,542)	(5,156)	(7,627)	(15,468)
Other comprehensive income (loss), net of taxes	10	17	32	52
Comprehensive income	$ 38,889	$ 37,834	$ 108,561	$ 90,991