Retirement benefits (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
Reclassifications out of accumulated other comprehensive income/(loss)
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	$ (5,680)	$ (3,768)	$ (11,701)	$ (7,641)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	4,999	3,289	10,312	6,684
Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	2	457	769	994
Retirement benefit plan items | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	5,680	3,768	11,701	7,641
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(4,999)	(3,289)	(10,312)	(6,684)
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(5,016)	(3,364)	(10,347)	(6,836)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	4,999	3,289	10,312	6,684
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plan items | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	5,016	3,364	10,347	6,836
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(4,999)	(3,289)	(10,312)	(6,684)
Total reclassifications	$ 17	$ 75	$ 35	$ 152