Electric utility segment - Consolidating statement of cash flows (unaudited) (Details 5) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities
Net income	$ 51,144	$ 48,279	$ 118,974	$ 136,293
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment			137,721	129,574
Other amortization			12,080	5,081
Increase in deferred income taxes			2,723	50,296
Allowance for equity funds used during construction	(2,057)	(1,937)	(5,366)	(4,933)
Change in cash overdraft			0	(1,038)
Changes in assets and liabilities
Decrease in fuel oil stock			35,942	15,784
Increase in regulatory assets			(23,458)	(17,531)
Change in prepaid and accrued income and utility revenue taxes			(8,458)	(2,044)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability			418	(2,594)
Net cash provided by operating activities			221,252	197,310
Cash flows from investing activities
Capital expenditures			(276,186)	(260,616)
Contributions in aid of construction			34,627	21,740
Other			4,084	674
Net cash used in investing activities			(502,997)	(400,892)
Cash flows from financing activities
Common stock dividends			(98,452)	(94,674)
Net increase in short-term borrowings with original maturities of three months or less			53,020	45,094
Other			(4,453)	(5,097)
Net cash provided by financing activities			334,620	176,101
Net increase (decrease) in cash and cash equivalents			52,875	(27,481)
Scenario, Previously Reported
Adjustments to reconcile net income to net cash provided by operating activities
Other amortization				5,454
Increase in deferred income taxes				49,270
Changes in assets and liabilities
Net cash provided by operating activities				173,410
Cash flows from investing activities
Capital expenditures				(236,003)
Other				(39)
Net cash used in investing activities				(376,992)
Hawaiian Electric Company
Cash flows from operating activities
Net income	43,276	39,149	103,531	109,339
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries			(29,249)	(28,651)
Common stock dividends received from subsidiaries			18,972	19,557
Depreciation of property, plant and equipment			88,167	81,903
Other amortization			5,409	765
Increase in deferred income taxes			46,493	52,274
Change in tax credits, net			3,680	4,725
Allowance for equity funds used during construction	(1,714)	(1,668)	(4,418)	(4,557)
Changes in assets and liabilities
Decrease (increase) in accounts receivable			(4,226)	(17,540)
Decrease in accrued unbilled revenues			6,283	(554)
Decrease in fuel oil stock			25,019	11,328
Increase in materials and supplies			(759)	875
Increase in regulatory assets			(19,138)	(15,159)
Decrease in accounts payable			(34,476)	(52,684)
Change in prepaid and accrued income and utility revenue taxes			(52,505)	(18,131)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability			0	(422)
Change in other assets and liabilities			(16,626)	(32,291)
Net cash provided by operating activities			136,157	110,777
Cash flows from investing activities
Capital expenditures			(204,406)	(181,565)
Contributions in aid of construction			30,153	12,352
Other			583	537
Advances from affiliates			4,100	(4,961)
Net cash used in investing activities			(169,570)	(173,637)
Cash flows from financing activities
Common stock dividends			(67,804)	(66,369)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(810)	(810)
Net increase in short-term borrowings with original maturities of three months or less			97,495	83,987
Other			(219)	(337)
Net cash provided by financing activities			28,662	16,471
Net increase (decrease) in cash and cash equivalents			(4,751)	(46,389)
Cash and cash equivalents, beginning of period			12,416	61,245
Cash and cash equivalents, end of period	7,665	14,856	7,665	14,856
Hawaiian Electric Company | Scenario, Previously Reported
Changes in assets and liabilities
Decrease in accounts payable				(70,916)
Change in other assets and liabilities				(31,754)
Cash flows from investing activities
Capital expenditures				(163,333)
Other				0
HELCO
Cash flows from operating activities
Net income	4,322	3,434	12,861	13,708
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment			27,938	26,926
Other amortization			2,055	1,950
Increase in deferred income taxes			907	5,146
Change in tax credits, net			372	687
Allowance for equity funds used during construction	(148)	(142)	(458)	(328)
Changes in assets and liabilities
Decrease (increase) in accounts receivable			(2,071)	(4,714)
Decrease in accrued unbilled revenues			3,696	626
Decrease in fuel oil stock			5,358	219
Increase in materials and supplies			(1,615)	(987)
Increase in regulatory assets			(3,944)	(2,594)
Decrease in accounts payable			(4,070)	(454)
Change in prepaid and accrued income and utility revenue taxes			(2,276)	(1,310)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability			0	0
Change in other assets and liabilities			436	(4,040)
Net cash provided by operating activities			39,189	34,835
Cash flows from investing activities
Capital expenditures			(34,048)	(34,565)
Contributions in aid of construction			2,940	6,229
Other			124	154
Advances from affiliates			0	1,000
Net cash used in investing activities			(30,984)	(27,182)
Cash flows from financing activities
Common stock dividends			(7,515)	(8,720)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(400)	(400)
Net increase in short-term borrowings with original maturities of three months or less			1,500	1,000
Other			(3)	(50)
Net cash provided by financing activities			(6,418)	(8,170)
Net increase (decrease) in cash and cash equivalents			1,787	(517)
Cash and cash equivalents, beginning of period			612	1,326
Cash and cash equivalents, end of period	2,399	809	2,399	809
HELCO | Scenario, Previously Reported
Changes in assets and liabilities
Decrease in accounts payable				(1,807)
Change in other assets and liabilities				(3,886)
Cash flows from investing activities
Capital expenditures				(33,212)
Other				0
Maui Electric
Cash flows from operating activities
Net income	7,764	6,594	16,999	15,554
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment			16,735	15,961
Other amortization			2,363	1,574
Increase in deferred income taxes			10,497	9,972
Change in tax credits, net			195	404
Allowance for equity funds used during construction	(195)	(127)	(490)	(48)
Change in cash overdraft				(1,038)
Changes in assets and liabilities
Decrease (increase) in accounts receivable			43	(442)
Decrease in accrued unbilled revenues			3,817	899
Decrease in fuel oil stock			5,565	4,237
Increase in materials and supplies			651	(1,483)
Increase in regulatory assets			(376)	222
Decrease in accounts payable			(1,829)	(142)
Change in prepaid and accrued income and utility revenue taxes			(6,540)	1,366
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability			331	(326)
Change in other assets and liabilities			(2,824)	(2,673)
Net cash provided by operating activities			45,137	44,037
Cash flows from investing activities
Capital expenditures			(27,067)	(37,588)
Contributions in aid of construction			1,534	3,159
Other			71	22
Advances from affiliates			(2,500)	0
Net cash used in investing activities			(27,962)	(34,407)
Cash flows from financing activities
Common stock dividends			(11,382)	(10,762)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(286)	(286)
Net increase in short-term borrowings with original maturities of three months or less			(5,600)	3,961
Other			(1)	(75)
Net cash provided by financing activities			(17,269)	(7,162)
Net increase (decrease) in cash and cash equivalents			(94)	2,468
Cash and cash equivalents, beginning of period			633	153
Cash and cash equivalents, end of period	539	2,621	539	2,621
Maui Electric | Scenario, Previously Reported
Adjustments to reconcile net income to net cash provided by operating activities
Other amortization				1,947
Changes in assets and liabilities
Decrease in accounts payable				(5,170)
Change in other assets and liabilities				(3,024)
Cash flows from investing activities
Capital expenditures				(32,560)
Other				0
Other subsidiaries
Cash flows from operating activities
Net income	0	0	0	0
Changes in assets and liabilities
Net cash provided by operating activities			0	0
Cash flows from investing activities
Capital expenditures			0	0
Contributions in aid of construction			0	0
Advances from affiliates			0	0
Net cash used in investing activities			0	0
Cash flows from financing activities
Net increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			101	101
Cash and cash equivalents, end of period	101	101	101	101
Consolidating adjustments
Cash flows from operating activities
Net income	(11,858)	(9,800)	(29,174)	(28,576)
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries			29,174	28,576
Common stock dividends received from subsidiaries			(18,897)	(19,482)
Increase in deferred income taxes			314
Changes in assets and liabilities
Decrease (increase) in accounts receivable			1,790	2,965
Change in prepaid and accrued income and utility revenue taxes			(314)
Change in other assets and liabilities			(1,790)	(2,965)
Net cash provided by operating activities			(18,897)	(19,482)
Cash flows from investing activities
Capital expenditures			0	0
Contributions in aid of construction			0	0
Advances from affiliates			(1,600)	3,961
Net cash used in investing activities			(1,600)	3,961
Cash flows from financing activities
Common stock dividends			18,897	19,482
Net increase in short-term borrowings with original maturities of three months or less			1,600	(3,961)
Net cash provided by financing activities			20,497	15,521
Net increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
Consolidating adjustments | Scenario, Previously Reported
Changes in assets and liabilities
Change in other assets and liabilities				(2,965)
HECO Consolidated
Cash flows from operating activities
Net income	43,504	39,377	104,217	110,025
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings of subsidiaries			(75)	(75)
Common stock dividends received from subsidiaries			75	75
Depreciation of property, plant and equipment			132,840	124,790
Other amortization			9,827	4,289
Increase in deferred income taxes			58,211	67,392
Change in tax credits, net			4,247	5,816
Allowance for equity funds used during construction	(2,057)	(1,937)	(5,366)	(4,933)
Change in cash overdraft			0	(1,038)
Changes in assets and liabilities
Decrease (increase) in accounts receivable			(4,464)	(19,731)
Decrease in accrued unbilled revenues			13,796	971
Decrease in fuel oil stock			35,942	15,784
Increase in materials and supplies			(1,723)	(1,595)
Increase in regulatory assets			(23,458)	(17,531)
Decrease in accounts payable			(40,375)	(53,280)
Change in prepaid and accrued income and utility revenue taxes			(61,635)	(18,075)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability			331	(748)
Change in other assets and liabilities			(20,804)	(41,969)
Net cash provided by operating activities			201,586	170,167
Cash flows from investing activities
Capital expenditures			(265,521)	(253,718)
Contributions in aid of construction			34,627	21,740
Other			778	713
Advances from affiliates			0	0
Net cash used in investing activities			(230,116)	(231,265)
Cash flows from financing activities
Common stock dividends			(67,804)	(66,369)
Preferred stock dividends of Hawaiian Electric and subsidiaries			(1,496)	(1,496)
Net increase in short-term borrowings with original maturities of three months or less			94,995	84,987
Other			(223)	(462)
Net cash provided by financing activities			25,472	16,660
Net increase (decrease) in cash and cash equivalents			(3,058)	(44,438)
Cash and cash equivalents, beginning of period			13,762	62,825
Cash and cash equivalents, end of period	$ 10,704	$ 18,387	$ 10,704	18,387
HECO Consolidated | Scenario, Previously Reported
Adjustments to reconcile net income to net cash provided by operating activities
Other amortization				4,662
Changes in assets and liabilities
Decrease in accounts payable				(77,893)
Change in other assets and liabilities				(41,629)
Net cash provided by operating activities				146,267
Cash flows from investing activities
Capital expenditures				(229,105)
Other				0
Net cash used in investing activities				$ (207,365)