Earnings per share and shareholders' equity (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	$ 20,022	$ 18,442	$ 39,478	$ 37,173
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(2,873)	(5,680)	(5,686)	(11,701)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	2,575	4,999	5,085	10,312
Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	357	2	(996)	769
Net unrealized gains (losses) on securities | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues-bank (net gains on sales of securities)	0	(738)	(1,715)	(738)
Derivatives qualified as cash flow hedges Interest rate contracts (settled in 2011) | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense			59
Derivatives qualified as cash flow hedges Interest rate contracts (settled in 2011) | Interest rate contracts | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense			118	118
Retirement benefit plans | 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	2,873	5,680	5,686	11,701
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(2,575)	(4,999)	(5,085)	(10,312)
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	(2,588)	(5,016)	(5,107)	(10,347)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	2,575	4,999	5,085	10,312
Hawaiian Electric Company, Inc. and Subsidiaries | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	13	17	22	35
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans | 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	2,588	5,016	5,107	10,347
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	$ (2,575)	$ (4,999)	$ (5,085)	$ (10,312)