Consolidating financial information (Details 2) - HECO (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income (loss) for common stock	$ 40,588	$ 38,800	$ 74,267	$ 77,116
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	5,680	3,768	11,701	7,641
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits	(4,999)	(3,289)	(10,312)	(6,684)
Other comprehensive income (loss), net of taxes	(8,305)	1,550	(8,366)	1,861
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	32,283	40,350	65,901	78,977
HECO
Net income (loss) for common stock	28,693	29,376	53,122	56,676
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	5,016	3,364	10,347	6,836
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits	(4,999)	(3,289)	(10,312)	(6,684)
Other comprehensive income (loss), net of taxes	17	75	35	152
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	28,710	29,451	53,157	56,828
HELCO
Net income (loss) for common stock	4,880	4,491	9,300	11,102
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	681	518	1,440	1,050
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits	(680)	(511)	(1,441)	(1,037)
Other comprehensive income (loss), net of taxes	1	7	(1)	13
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	4,881	4,498	9,299	11,115
MECO
Net income (loss) for common stock	3,788	3,760	10,353	5,640
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	622	412	1,279	885
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits	(623)	(406)	(1,279)	(873)
Other comprehensive income (loss), net of taxes	(1)	6		12
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	3,787	3,766	10,353	5,652
Other subsidiaries
Net income (loss) for common stock	(1)	(1)	(1)	(2)
Retirement benefit plans:
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	(1)	(1)	(1)	(2)
Consolidating adjustments
Net income (loss) for common stock	(8,667)	(8,250)	(19,652)	(16,740)
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	(1,303)	(930)	(2,719)	(1,935)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits	1,303	917	2,720	1,910
Other comprehensive income (loss), net of taxes		(13)	1	(25)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	(8,667)	(8,263)	(19,651)	(16,765)
HECO Consolidated
Net income (loss) for common stock	28,693	29,376	53,122	56,676
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	5,016	3,364	10,347	6,836
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits	(4,999)	(3,289)	(10,312)	(6,684)
Other comprehensive income (loss), net of taxes	17	75	35	152
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	$ 28,710	$ 29,451	$ 53,157	$ 56,828