Share-based compensation Share-based Compensation Expense and Related Income Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense (in dollars)	$ 9,300	$ 7,800	$ 6,700
Income tax benefit (in dollars)	3,400	2,800	2,400
Capitalized share-based compensation expense	160	110	80
Hawaiian Electric Company, Inc. and Subsidiaries
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense (in dollars)	3,100	2,300	1,800
Income tax benefit (in dollars)	$ 1,200	$ 900	$ 700