Bank segment (HEI only) Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income	$ 42,793	$ 51,144	$ 35,491	$ 32,339	$ 33,726	$ 48,279	$ 41,754	$ 46,260	$ 161,767	$ 170,019	$ 163,599
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 $1,541, $(3,856) and $9,037 for 2015, 2014 and 2013, respectively									(2,334)	5,840	(13,686)
Less: reclassification adjustment for net realized gains included in net income, net of taxes of nil, $1,132 and $488 for 2015, 2014 and 2013, respectively									0	(1,715)	(738)
Retirement benefit plans:
Net gains (losses) arising during the period, net of (taxes) benefits of ($59), $6,164 and ($10,450) for 2015, 2014 and 2013, respectively									5,889	(234,166)	223,177
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 $1,011, $561 and $1,187 for 2015, 2014 and 2013, respectively									22,465	11,344	23,280
Other comprehensive income (loss), net of taxes									1,116	(10,628)	9,673
Comprehensive income attributable to Hawaiian Electric Company, Inc.									160,993	157,501	171,382
American Savings Bank (ASB)
Net income									54,730	51,301	57,727
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 $1,541, $(3,856) and $9,037 for 2015, 2014 and 2013, respectively									(2,334)	5,840	(13,686)
Less: reclassification adjustment for net realized gains included in net income, net of taxes of nil, $1,132 and $488 for 2015, 2014 and 2013, respectively									0	(1,715)	(738)
Retirement benefit plans:
Net gains (losses) arising during the period, net of (taxes) benefits of ($59), $6,164 and ($10,450) for 2015, 2014 and 2013, respectively									90	(9,336)	15,826
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 $1,011, $561 and $1,187 for 2015, 2014 and 2013, respectively									1,531	850	1,797
Other comprehensive income (loss), net of taxes									(713)	(4,361)	3,199
Comprehensive income attributable to Hawaiian Electric Company, Inc.									$ 54,017	$ 46,940	$ 60,926