Shareholders' equity Reclassification Out Of AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Interest rate contracts (settled in 2011)	$ 76,352	$ 75,479	$ 78,151
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(11,344)	(23,280)	(15,291)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(207,833)	222,595	(75,471)
Amount reclassified from AOCI
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications	217,698	(199,818)	90,917
Amount reclassified from AOCI | Unrealized losses on derivatives
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on securities	(1,715)	(738)	(81)
Interest rate contracts (settled in 2011)	236	235	236
Amount reclassified from AOCI | Retirement benefit plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	11,344	23,280	15,291
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	207,833	(222,595)	75,471
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	(10,212)	(20,694)	(13,673)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	(207,833)	222,595	(75,471)
Hawaiian Electric Company, Inc. and Subsidiaries | Amount reclassified from AOCI
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications	218,045	(201,901)	89,144
Hawaiian Electric Company, Inc. and Subsidiaries | Amount reclassified from AOCI | Retirement benefit plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost	10,212	20,694	13,673
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets	$ 207,833	$ (222,595)	$ 75,471