Earnings per share and shareholders' equity (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	$ 18,906	$ 20,022	$ 38,006	$ 39,478
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(5,780)	(2,873)	(11,239)	(5,686)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	5,272	2,575	10,183	5,085
Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	567	357	1,174	(996)
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	0	0	(1,715)
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	59	59	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	5,780	2,873	11,239	5,686
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(5,272)	(2,575)	(10,183)	(5,085)
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	(5,257)	(2,588)	(10,190)	(5,107)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	5,272	2,575	10,183	5,085
Hawaiian Electric Company, Inc. and Subsidiaries | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(15)	13	7	22
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	5,257	2,588	10,190	5,107
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	$ (5,272)	$ (2,575)	$ (10,183)	$ (5,085)