Shareholders' equity Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (16,750)	$ (26,423)	$ (19,137)
Current period other comprehensive income (loss)	(10,628)	9,673	(7,286)
Ending balance	(27,378)	(16,750)	(26,423)
Net unrealized gains (losses) on securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(3,663)	10,761	9,886
Current period other comprehensive income (loss)	4,125	(14,424)	875
Ending balance	462	(3,663)	10,761
Unrealized losses on derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(525)	(760)	(996)
Current period other comprehensive income (loss)	236	235	236
Ending balance	(289)	(525)	(760)
Retirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(12,562)	(36,424)	(28,027)
Current period other comprehensive income (loss)	(14,989)	23,862	(8,397)
Ending balance	(27,551)	(12,562)	(36,424)
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	608	(970)	(32)
Current period other comprehensive income (loss)	(563)	1,578	(938)
Ending balance	$ 45	$ 608	$ (970)