Earnings per share and shareholders' equity (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	$ 19,100	$ 19,456
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(5,459)	(2,813)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	4,911	2,510
Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	4,058	(1,353)
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)	3,451	(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
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	5,459	2,813
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(4,911)	(2,510)
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	(4,933)	(2,519)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	4,911	2,510
Hawaiian Electric Company, Inc. and Subsidiaries | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	22	9
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	4,933	2,519
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	$ (4,911)	$ (2,510)