Electric utility segment Consolidating Statement of Cash Flows (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
Cash flows from operating activities
Net income (loss)	$ 42,793	$ 51,144	$ 35,491	$ 32,339	$ 33,726	$ 48,279	$ 41,754	$ 46,260	$ 161,767	$ 170,019	$ 163,599
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment									183,966	172,762	160,061
Other amortization									11,619	10,282	7,324
Impairment of utility assets									6,021	1,866	0
Other									1,672	758	0
Increase in deferred income taxes									41,433	104,226	80,145
Allowance for equity funds used during construction									(6,928)	(6,771)	(5,561)
Change in cash overdraft									0	(1,038)	1,038
Decrease in fuel oil stock									34,830	28,041	27,332
Increase in regulatory assets									(24,182)	(17,000)	(65,461)
Change in prepaid and accrued income taxes and utility revenue taxes									(42,596)	(39,091)	(19,406)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability									852	22,251	(33,014)
Net cash provided by operating activities									355,880	325,420	361,568
Cash flows from investing activities
Capital expenditures									(363,804)	(364,826)	(389,438)
Contributions in aid of construction									40,239	41,806	32,160
Other									7,940	1,125	1,177
Net cash used in investing activities									(705,724)	(592,449)	(598,182)
Cash flows from financing activities
Common stock dividends									(131,765)	(126,458)	(98,383)
Proceeds from issuance of common stock									104,435	26,898	55,086
Proceeds from issuance of long-term debt									80,000	125,000	286,000
Repayment of long-term debt									0	(111,400)	(216,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less									(15,909)	13,490	21,789
Other									(833)	(456)	(1,187)
Net cash used in financing activities									474,780	222,535	236,988
Net increase (decrease) in cash and equivalents									124,936	(44,494)	374
HECO
Cash flows from operating activities
Net income (loss)									136,794	138,721	124,009
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings									(43,020)	(41,064)	(41,510)
Common stock dividends received from subsidiaries									25,296	26,076	28,505
Depreciation of property, plant and equipment									117,682	109,204	99,738
Other amortization									4,678	4,535	2,549
Impairment of utility assets									4,573	1,866
Other									4,403	758
Increase in deferred income taxes									53,338	56,901	41,409
Change in tax credits, net									4,284	4,998	5,152
Allowance for equity funds used during construction									(5,641)	(6,085)	(4,495)
Change in cash overdraft											0
Decrease in accounts receivable									15,652	16,213	49,974
Decrease (increase) in accrued unbilled revenues									29,733	4,680	(7,152)
Decrease in fuel oil stock									25,060	25,098	23,563
Decrease (increase) in materials and supplies									2,233	2,357	(5,598)
Increase in regulatory assets									(20,356)	(14,620)	(46,047)
Increase (decrease) in accounts payable									(42,751)	(56,044)	18,527
Change in prepaid and accrued income taxes and utility revenue taxes									(50,382)	(4,166)	4,632
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability									870	(562)	2,325
Changes in other assets and liabilities									(24,197)	(50,180)	(20,613)
Net cash provided by operating activities									238,249	218,686	274,968
Cash flows from investing activities
Capital expenditures									(267,621)	(237,970)	(262,562)
Contributions in aid of construction									35,955	30,021	21,686
Advances from affiliates									16,100	(9,261)	2,561
Other									924	604	677
Investment in consolidated subsidiary										0	(12,461)
Net cash used in investing activities									(214,642)	(216,606)	(250,099)
Cash flows from financing activities
Common stock dividends									(90,405)	(88,492)	(81,578)
Preferred stock dividends of Hawaiian Electric and subsidiaries									(1,080)	(1,080)	(1,080)
Proceeds from issuance of common stock										40,000	78,500
Proceeds from issuance of long-term debt									50,000		140,000
Repayment of long-term debt										0	(90,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less									23,000	(1,000)	(17,050)
Other									(1,257)	(337)	(681)
Net cash used in financing activities									(19,742)	(50,909)	28,111
Net increase (decrease) in cash and equivalents									3,865	(48,829)	52,980
Cash and cash equivalents, beginning of period				12,416				61,245	12,416	61,245	8,265
Cash and cash equivalents, end of period	16,281				12,416				16,281	12,416	61,245
HELCO
Cash flows from operating activities
Net income (loss)									21,289	19,223	20,670
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment									37,250	35,904	34,188
Other amortization									2,124	2,926	2,360
Impairment of utility assets									724	0
Other									(2,476)
Increase in deferred income taxes									8,295	12,083	10,569
Change in tax credits, net									527	680	818
Allowance for equity funds used during construction									(604)	(472)	(643)
Change in cash overdraft											0
Decrease in accounts receivable									3,420	7,150	(1,459)
Decrease (increase) in accrued unbilled revenues									4,593	1,174	(2,707)
Decrease in fuel oil stock									5,490	378	1,307
Decrease (increase) in materials and supplies									(201)	219	(1,547)
Increase in regulatory assets									(3,930)	(3,357)	(9,237)
Increase (decrease) in accounts payable									(6,425)	(6,645)	1,525
Change in prepaid and accrued income taxes and utility revenue taxes									(6,166)	(3,251)	(4,114)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability									(161)	0	(1)
Changes in other assets and liabilities									(3,545)	(12,907)	(6,894)
Net cash provided by operating activities									60,204	53,105	44,835
Cash flows from investing activities
Capital expenditures									(48,645)	(49,895)	(58,416)
Contributions in aid of construction									2,160	7,695	7,590
Advances from affiliates									(15,500)	1,000	17,050
Other									132	492	21
Net cash used in investing activities									(61,853)	(40,708)	(33,755)
Cash flows from financing activities
Common stock dividends									(10,021)	(11,627)	(14,388)
Preferred stock dividends of Hawaiian Electric and subsidiaries									(534)	(534)	(534)
Proceeds from issuance of long-term debt									25,000		56,000
Repayment of long-term debt										(11,400)	(56,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less									(10,500)	10,500
Other									(226)	(50)	(273)
Net cash used in financing activities									3,719	(13,111)	(15,195)
Net increase (decrease) in cash and equivalents									2,070	(714)	(4,115)
Cash and cash equivalents, beginning of period				612				1,326	612	1,326	5,441
Cash and cash equivalents, end of period	2,682				612				2,682	612	1,326
MECO
Cash flows from operating activities
Net income (loss)									22,546	22,656	21,658
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment									22,448	21,279	20,099
Other amortization									2,137	2,436	2,825
Impairment of utility assets									724
Other									(255)
Increase in deferred income taxes									13,707	13,963	12,529
Change in tax credits, net									33	384	1,047
Allowance for equity funds used during construction									(683)	(214)	(423)
Change in cash overdraft										(1,038)	1,038
Decrease in accounts receivable									4,617	3,483	1,178
Decrease (increase) in accrued unbilled revenues									5,767	896	33
Decrease in fuel oil stock									4,280	2,565	2,462
Decrease (increase) in materials and supplies									789	(2,648)	(814)
Increase in regulatory assets									104	977	(10,177)
Increase (decrease) in accounts payable									(5,379)	(2,838)	(5,321)
Change in prepaid and accrued income taxes and utility revenue taxes									(6,548)	3,381	(2,546)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability									416	(399)	(84)
Changes in other assets and liabilities									(4,554)	(3,703)	(8,034)
Net cash provided by operating activities									60,149	61,180	35,470
Cash flows from investing activities
Capital expenditures									(33,895)	(48,814)	(57,066)
Contributions in aid of construction									2,124	4,090	2,884
Advances from affiliates									(7,500)	0	0
Other									84	68	209
Net cash used in investing activities									(39,187)	(44,656)	(53,973)
Cash flows from financing activities
Common stock dividends									(15,175)	(14,349)	(14,017)
Preferred stock dividends of Hawaiian Electric and subsidiaries									(381)	(381)	(381)
Proceeds from issuance of common stock										0	12,461
Proceeds from issuance of long-term debt									5,000		40,000
Repayment of long-term debt										0	(20,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less									(5,600)	(1,239)	(2,561)
Other									(54)	(75)	(195)
Net cash used in financing activities									(16,210)	(16,044)	15,307
Net increase (decrease) in cash and equivalents									4,752	480	(3,196)
Cash and cash equivalents, beginning of period				633				153	633	153	3,349
Cash and cash equivalents, end of period	5,385				633				5,385	633	153
Other subsidiaries
Cash flows from operating activities
Net income (loss)									0	0	(3)
Adjustments to reconcile net income to net cash provided by operating activities
Changes in other assets and liabilities									0	0	0
Net cash provided by operating activities									0	0	(3)
Cash flows from financing activities
Proceeds from issuance of common stock											0
Net increase (decrease) in cash and equivalents									0	0	(3)
Cash and cash equivalents, beginning of period				101				101	101	101	104
Cash and cash equivalents, end of period	101				101				101	101	101
Consolidating adjustments
Cash flows from operating activities
Net income (loss)									(42,920)	(40,964)	(41,410)
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings									42,920	40,964	41,410
Common stock dividends received from subsidiaries									(25,196)	(25,976)	(28,405)
Increase in deferred income taxes									286
Decrease in accounts receivable									38	(103)	(248)
Change in prepaid and accrued income taxes and utility revenue taxes									0
Changes in other assets and liabilities									(324)	103	248
Net cash provided by operating activities									(25,196)	(25,976)	(28,405)
Cash flows from investing activities
Advances from affiliates									6,900	8,261	(19,611)
Other									0	0
Investment in consolidated subsidiary										0	12,461
Net cash used in investing activities									6,900	8,261	(7,150)
Cash flows from financing activities
Common stock dividends									25,196	25,976	28,405
Proceeds from issuance of common stock										0	(12,461)
Proceeds from issuance of long-term debt									0
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less									(6,900)	(8,261)	19,611
Net cash used in financing activities									18,296	17,715	35,555
HECO Consolidated
Cash flows from operating activities
Net income (loss)	33,492	$ 43,504	$ 33,340	27,373	29,611	$ 39,377	$ 34,729	35,919	137,709	139,636	124,924
Adjustments to reconcile net income to net cash provided by operating activities
Equity in earnings									(100)	(100)	(100)
Common stock dividends received from subsidiaries									100	100	100
Depreciation of property, plant and equipment									177,380	166,387	154,025
Other amortization									8,939	9,897	7,734
Impairment of utility assets									6,021	1,866	0
Other									1,672	758	0
Increase in deferred income taxes									75,626	82,947	64,507
Change in tax credits, net									4,844	6,062	7,017
Allowance for equity funds used during construction									(6,928)	(6,771)	(5,561)
Change in cash overdraft									0	(1,038)	1,038
Decrease in accounts receivable									23,727	26,743	49,445
Decrease (increase) in accrued unbilled revenues									40,093	6,750	(9,826)
Decrease in fuel oil stock									34,830	28,041	27,332
Decrease (increase) in materials and supplies									2,821	(72)	(7,959)
Increase in regulatory assets									(24,182)	(17,000)	(65,461)
Increase (decrease) in accounts payable									(54,555)	(65,527)	14,731
Change in prepaid and accrued income taxes and utility revenue taxes									(63,096)	(4,036)	(2,028)
Increase (decrease) in defined benefit pension and other postretirement benefit plans liability									1,125	(961)	2,240
Changes in other assets and liabilities									(32,620)	(66,687)	(35,293)
Net cash provided by operating activities									333,406	306,995	326,865
Cash flows from investing activities
Capital expenditures									(350,161)	(336,679)	(378,044)
Contributions in aid of construction									40,239	41,806	32,160
Advances from affiliates											0
Other									1,140	1,164	907
Investment in consolidated subsidiary											0
Net cash used in investing activities									(308,782)	(293,709)	(344,977)
Cash flows from financing activities
Common stock dividends									(90,405)	(88,492)	(81,578)
Preferred stock dividends of Hawaiian Electric and subsidiaries									(1,995)	(1,995)	(1,995)
Proceeds from issuance of common stock									0	40,000	78,500
Proceeds from issuance of long-term debt									80,000	0	236,000
Repayment of long-term debt									0	(11,400)	(166,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less										0	0
Other									(1,537)	(462)	(1,149)
Net cash used in financing activities									(13,937)	(62,349)	63,778
Net increase (decrease) in cash and equivalents									10,687	(49,063)	45,666
Cash and cash equivalents, beginning of period				$ 13,762				$ 62,825	13,762	62,825	17,159
Cash and cash equivalents, end of period	$ 24,449				$ 13,762				$ 24,449	$ 13,762	$ 62,825