Electric utility segment Consolidating Statement 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 for common stock	$ 42,320	$ 50,673	$ 35,018	$ 31,866	$ 33,253	$ 47,808	$ 41,281	$ 45,787	$ 159,877	$ 168,129	$ 161,709
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) 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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively									22,465	11,344	23,280
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively									(25,139)	207,833	(222,595)
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
HECO
Net income for common stock									135,714	137,641	122,929
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) for 2015, 2014 and 2013, respectively									5,638	(218,608)	203,479
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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively									20,381	10,212	20,694
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively									(25,139)	207,833	(222,595)
Other comprehensive income (loss), net of taxes									880	(563)	1,578
Comprehensive income attributable to Hawaiian Electric Company, Inc.									136,594	137,078	124,507
HELCO
Net income for common stock									20,755	18,689	20,136
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) for 2015, 2014 and 2013, respectively									(2,710)	(28,725)	30,542
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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively									2,728	1,270	2,880
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively									104	27,437	(33,277)
Other comprehensive income (loss), net of taxes									122	(18)	145
Comprehensive income attributable to Hawaiian Electric Company, Inc.									20,877	18,671	20,281
MECO
Net income for common stock									22,165	22,275	21,277
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) for 2015, 2014 and 2013, respectively									(1,352)	(29,352)	27,820
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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively									2,503	1,090	2,557
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively									(1,107)	28,257	(30,254)
Other comprehensive income (loss), net of taxes									44	(5)	123
Comprehensive income attributable to Hawaiian Electric Company, Inc.									22,209	22,270	21,400
Other subsidiaries
Net income for common stock									0	0	(3)
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) for 2015, 2014 and 2013, respectively											0
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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively											0
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively											0
Other comprehensive income (loss), net of taxes											0
Comprehensive income attributable to Hawaiian Electric Company, Inc.									0	0	(3)
Consolidating adjustments
Net income for common stock									(42,920)	(40,964)	(41,410)
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) for 2015, 2014 and 2013, respectively									4,062	58,077	(58,362)
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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively									(5,231)	(2,360)	(5,437)
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively									1,003	(55,694)	63,531
Other comprehensive income (loss), net of taxes									(166)	23	(268)
Comprehensive income attributable to Hawaiian Electric Company, Inc.									(43,086)	(40,941)	(41,678)
HECO Consolidated
Net income for common stock	$ 32,993	$ 43,006	$ 32,841	$ 26,874	$ 29,112	$ 38,879	$ 34,230	$ 35,420	135,714	137,641	122,929
Net gains (losses) arising during the period, net of (taxes) benefits of ($3,753), $149,364 and ($142,478) for 2015, 2014 and 2013, respectively									5,638	(218,608)	203,479
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 $14,344, $7,245 and $14,870 for 2015, 2014 and 2013, respectively									20,381	10,212	20,694
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of (taxes) benefits of $16,011, ($132,373) and $141,777 for 2015, 2014 and 2013, respectively									(25,139)	207,833	(222,595)
Other comprehensive income (loss), net of taxes									880	(563)	1,578
Comprehensive income attributable to Hawaiian Electric Company, Inc.									$ 136,594	$ 137,078	$ 124,507