Earnings per share and shareholders' equity (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	$ 19,229	$ 19,170	$ 57,235	$ 58,648
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(5,611)	(2,829)	(16,850)	(8,515)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,243, $1,619, $9,729 and $4,858 for the respective periods	(5,091)	(2,542)	(15,274)	(7,627)
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	(5,095)	(2,552)	(15,285)	(7,659)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,243, $1,619, $9,729 and $4,858 for the respective periods	(5,091)	(2,542)	(15,274)	(7,627)
Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	579	346	1,753	(650)
Amount reclassified from AOCI | Net unrealized gains (losses) on securities
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues-bank (net gains on sales of securities)	0	0	0	1,715
Amount reclassified from AOCI | Derivatives qualified as cash flow hedges Interest rate contracts (settled in 2011) | Interest rate contracts
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	59	59	177	177
Amount reclassified from AOCI | Retirement benefit plans
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	(5,611)	(2,829)	(16,850)	(8,515)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,243, $1,619, $9,729 and $4,858 for the respective periods	(5,091)	(2,542)	(15,274)	(7,627)
Amount reclassified from AOCI | Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	4	10	11	32
Amount reclassified from AOCI | Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans
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	(5,095)	(2,552)	(15,285)	(7,659)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,243, $1,619, $9,729 and $4,858 for the respective periods	$ (5,091)	$ (2,542)	$ (15,274)	$ (7,627)