Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income for common stock	$ 44,634	$ 127,142	$ 44,128	$ 32,352	$ 42,320	$ 50,673	$ 35,018	$ 31,866	$ 248,256	$ 159,877	$ 168,129
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 $3,763, $1,541 and $(3,856) for 2016, 2015 and 2014, respectively									(5,699)	(2,334)	5,840
Less: reclassification adjustment for net realized gains included in net income, net of taxes of $238, nil and $1,132 for 2016, 2015 and 2014, respectively									(360)	0	(1,715)
Derivatives qualified as cash flow hedges:
Effective portion of foreign currency hedge net unrealized losses arising during the period, net of tax benefits of $179, nil and nil for 2016, 2015 and 2014, respectively									(281)	0	0
Less: reclassification adjustment to net income, net of (taxes) benefit of $(76), $150 and $150 for 2016, 2015 and 2014, respectively									(119)	235	236
Retirement benefit plans:
Net gains (losses) arising during the period, net of (taxes) benefits of $27,703, $(3,753) and $149,364 for 2016, 2015 and 2014, respectively									(43,510)	5,889	(234,166)
Less: amortization of prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $9,267, $14,344 and $7,245 for 2016, 2015 and 2014, respectively									14,518	22,465	11,344
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $(18,206), $16,011 and $(132,373) for 2016, 2015 and 2014, respectively									28,584	(25,139)	207,833
Other comprehensive income (loss), net of taxes									(6,867)	1,116	(10,628)
Comprehensive income attributable to Hawaiian Electric Company, Inc.									$ 241,389	$ 160,993	$ 157,501