Earnings per share and shareholders' equity (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	$ 19,170	$ 19,043	$ 58,648	$ 56,216
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(2,829)	(5,789)	(8,515)	(17,490)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	2,542	5,156	7,627	15,468
Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	346	692	(650)	1,461
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	(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	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			177	177
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	2,829	5,789	8,515	17,490
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(2,542)	(5,156)	(7,627)	(15,468)
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	(2,552)	(5,173)	(7,659)	(15,520)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	2,542	5,156	7,627	15,468
Hawaiian Electric Company, Inc. and Subsidiaries | Amount reclassified from AOCI
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	10	17	32	52
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	2,552	5,173	7,659	15,520
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	$ (2,542)	$ (5,156)	$ (7,627)	$ (15,468)