Bank segment (HEI only) Statements of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$ 33,630	$ 48,286	$ 41,894	$ 46,400	$ 39,486	$ 48,707	$ 41,061	$ 34,152	$ 170,210	$ 163,406	$ 140,548
Net unrealized gains (losses) on available-for sale investment securities:
Net unrealized gains (losses) on available-for sale investment securities arising during the period, net of (taxes) benefits of $(3,856), $9,037 and ($631) for 2014, 2013 and 2012, respectively									5,840	(13,686)	956
Less: reclassification adjustment for net realized gains included in net income, net of taxes of $1,132, $488 and $53 for 2014, 2013 and 2012, respectively									(1,715)	(738)	(81)
Retirement benefit plans:
Net gains (losses) arising during the period, net of (taxes) benefits of $6,164, ($10,450) and $5,240 for 2014, 2013 and 2012, respectively									(234,166)	223,177	(99,159)
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $561, $1,187 and $684 for 2014, 2013 and 2012, respectively									11,344	23,280	15,291
Other comprehensive income (loss), net of taxes									(10,628)	9,673	(7,286)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.									157,692	171,189	131,372
American Savings Bank (ASB)
Net income									51,492	57,534	58,637
Net unrealized gains (losses) on available-for sale investment securities:
Net unrealized gains (losses) on available-for sale investment securities arising during the period, net of (taxes) benefits of $(3,856), $9,037 and ($631) for 2014, 2013 and 2012, respectively									5,840	(13,686)	956
Less: reclassification adjustment for net realized gains included in net income, net of taxes of $1,132, $488 and $53 for 2014, 2013 and 2012, respectively									(1,715)	(738)	(81)
Retirement benefit plans:
Net gains (losses) arising during the period, net of (taxes) benefits of $6,164, ($10,450) and $5,240 for 2014, 2013 and 2012, respectively									(9,336)	15,826	(7,936)
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $561, $1,187 and $684 for 2014, 2013 and 2012, respectively									850	1,797	1,036
Other comprehensive income (loss), net of taxes									(4,361)	3,199	(6,025)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.									$ 47,131	$ 60,733	$ 52,612