Consolidating financial information (Details 2) - HECO (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income (loss) for common stock	$ 48,236	$ 47,706	$ 122,503	$ 124,822
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	5,789	3,826	17,490	11,467
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	(5,156)	(3,342)	(15,468)	(10,026)
Other comprehensive income (loss), net of taxes	(897)	1,586	(9,263)	3,447
Comprehensive income	47,339	49,292	113,240	128,269
HECO
Net income (loss) for common stock	37,817	38,375	90,939	95,051
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	5,173	3,419	15,520	10,255
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	(5,156)	(3,342)	(15,468)	(10,026)
Other comprehensive income (loss), net of taxes	17	77	52	229
Comprehensive income	37,834	38,452	90,991	95,280
HELCO
Net income (loss) for common stock	5,444	4,728	14,744	15,830
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	720	526	2,160	1,576
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	(721)	(521)	(2,162)	(1,558)
Other comprehensive income (loss), net of taxes	(1)	5	(2)	18
Comprehensive income	5,443	4,733	14,742	15,848
MECO
Net income (loss) for common stock	5,351	6,558	15,704	12,198
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	639	443	1,918	1,328
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	(639)	(436)	(1,918)	(1,309)
Other comprehensive income (loss), net of taxes	0	7		19
Comprehensive income	5,351	6,565	15,704	12,217
Other subsidiaries
Net income (loss) for common stock	(1)	(1)	(2)	(3)
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	0
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	0
Other comprehensive income (loss), net of taxes	0
Comprehensive income	(1)	(1)	(2)	(3)
Consolidating adjustments
Net income (loss) for common stock	(10,794)	(11,285)	(30,446)	(28,025)
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	(1,359)	(969)	(4,078)	(2,904)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	1,360	957	4,080	2,867
Other comprehensive income (loss), net of taxes	1	(12)	2	(37)
Comprehensive income	(10,793)	(11,297)	(30,444)	(28,062)
HECO Consolidated
Net income (loss) for common stock	37,817	38,375	90,939	95,051
Retirement benefit plans:
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits	5,173	3,419	15,520	10,255
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes	(5,156)	(3,342)	(15,468)	(10,026)
Other comprehensive income (loss), net of taxes	17	77	52	229
Comprehensive income	$ 37,834	$ 38,452	$ 90,991	$ 95,280