Electric utility segment - Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Depreciation of property, plant and equipment	$ 261,701	$ 254,990	$ 244,477
Other amortization	31,832	27,316	25,928
Deferred income tax expense (benefit)	(486,188)	9,352	(33,157)
Allowance for equity funds used during construction	(13,786)	(15,164)	(10,574)
Other	(13,790)	(2,989)	(5,323)
Changes in assets and liabilities
Decrease in fuel oil stock	49,361	43,388	(87,569)
Increase in regulatory assets	(22,743)	(10,613)	34,600
Increase in regulatory liabilities	48,433	54,470	44,888
Change in prepaid and accrued income taxes, tax credits and revenue taxes	(25,525)	(9,858)	120,738
Change in defined benefit pension and other postretirement benefit plans asset/liability	(9,358)	(8,215)	(4,564)
Increase in wildfire tort-related claims	1,840,000	75,000	0
Change in other assets and liabilities	(53,812)	(57,255)	(25,924)
Net cash provided by operating activities	487,481	551,471	454,476
Cash flows from investing activities
Capital expenditures	(344,251)	(442,727)	(339,333)
Other	10,330	6,558	14,184
Net cash used in investing activities	258,318	(257,399)	(1,128,682)
Cash flows from financing activities
Common stock dividends	0	(73,957)	(111,229)
Proceeds from issuance of common stock/capital contribution from parent	556,612	1,223	0
Proceeds from issuance of long-term debt	5,475	625,000	227,312
Repayment of long-term debt and funds transferred for repayment of long-term debt	(97,698)	(167,080)	(221,910)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	0	(137,650)	83,652
Payments of obligations under finance leases	(4,678)	(3,519)
Proceeds from issuance of short-term debt	50,000	65,000	35,000
Other	(13,867)	(5,133)	(2,041)
Net cash provided by (used in) financing activities	154,705	195,575	567,671
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	900,504	489,647	(106,535)
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	694,574	204,927	311,462
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31	1,595,078	694,574	204,927
Less: Restricted cash	(492,317)	(15,028)	(5,050)
Cash and cash equivalents	750,535	244,091	43,728
Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income (loss)	(1,224,367)	195,947	190,924
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Equity in earnings of subsidiaries	0	0	0
Common stock dividends received from subsidiaries		0	0
Depreciation of property, plant and equipment	251,142	243,705	235,424
Other amortization	31,828	26,490	25,320
Deferred income tax expense (benefit)	(481,624)	1,439	(41,415)
Gain/Loss on sale of receivables to BRWR	0
State refundable credit	(11,914)	(11,325)	(10,999)
Bad debt expense	4,720	8,161	6,027
Allowance for equity funds used during construction	(13,786)	(15,164)	(10,574)
Other	(6,311)	460	(139)
Changes in assets and liabilities
Decrease (increase) in accounts receivable	88,376	(65,004)	(91,742)
Decrease (increase) in accrued unbilled revenues	7,561	(3,048)	(54,023)
Decrease in fuel oil stock	49,334	43,293	(87,452)
Decrease (increase) in materials and supplies	(4,033)	(34,865)	(7,691)
Increase in regulatory assets	(22,743)	(10,613)	34,600
Increase in regulatory liabilities	48,433	54,470	44,888
Increase (decrease) in accounts payable	9,644	20,454	22,355
Change in prepaid and accrued income taxes, tax credits and revenue taxes	(26,542)	1,878	103,198
Change in defined benefit pension and other postretirement benefit plans asset/liability	(9,218)	(8,186)	(4,828)
Increase in wildfire tort-related claims	1,840,000	75,000	0
Change in other assets and liabilities	(64,767)	(48,725)	(25,943)
Net cash provided by operating activities	465,733	474,367	327,930
Cash flows from investing activities
Capital expenditures	(329,479)	(438,775)	(329,457)
Advances from (to) affiliates	0	0	0
Other	11,848	6,176	5,372
Net cash used in investing activities	(317,631)	(432,599)	(324,085)
Cash flows from financing activities
Common stock dividends	(26,000)	(129,000)	(125,900)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(1,995)	(1,995)	(1,995)
Proceeds from issuance of common stock/capital contribution from parent	270	0	13,101
Proceeds from issuance of long-term debt	0	350,000	60,000
Repayment of long-term debt and funds transferred for repayment of long-term debt	(81,000)	(100,000)	(52,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	0	(87,967)	87,967
Payments of obligations under finance leases	(4,119)	(3,128)	(670)
Proceeds from issuance of short-term debt	50,000	0	0
Other	(9,187)	(843)	(364)
Net cash provided by (used in) financing activities	(72,031)	27,067	(19,861)
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	76,071	68,835	(16,016)
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	108,077	39,242	55,258
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31	184,148	108,077	39,242
Less: Restricted cash	0	(2,000)	0
Cash and cash equivalents	184,148	106,077	39,242
Consolidating adjustments | Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income (loss)	248,004	(44,809)	(47,493)
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Equity in earnings of subsidiaries	(248,004)	44,809	47,493
Common stock dividends received from subsidiaries		(24,450)	(31,600)
Depreciation of property, plant and equipment	0	0	0
Other amortization	0	0	0
Deferred income tax expense (benefit)	0	0	0
Gain/Loss on sale of receivables to BRWR	0
State refundable credit	0	0	0
Bad debt expense	0	0	0
Allowance for equity funds used during construction	0	0	0
Other	0	0	0
Changes in assets and liabilities
Decrease (increase) in accounts receivable	172,466	55,096	4,649
Decrease (increase) in accrued unbilled revenues	0	0	0
Decrease in fuel oil stock	0	0	0
Decrease (increase) in materials and supplies	0	0	0
Increase in regulatory assets	0	0	0
Increase in regulatory liabilities	0	0	0
Increase (decrease) in accounts payable	0	0	0
Change in prepaid and accrued income taxes, tax credits and revenue taxes	(2,549)	0	0
Change in defined benefit pension and other postretirement benefit plans asset/liability	0	0	0
Increase in wildfire tort-related claims	0	0
Change in other assets and liabilities	(172,466)	(55,096)	(4,649)
Net cash provided by operating activities	(2,549)	(24,450)	(31,600)
Cash flows from investing activities
Capital expenditures	0	0	0
Advances from (to) affiliates	46,700	44,300	25,200
Other	22,349	0	9,046
Net cash used in investing activities	69,049	44,300	34,246
Cash flows from financing activities
Common stock dividends	0	24,450	31,600
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	0	0
Proceeds from issuance of common stock/capital contribution from parent	(19,800)		(9,046)
Proceeds from issuance of long-term debt		0	0
Repayment of long-term debt and funds transferred for repayment of long-term debt	0	0	0
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	(46,700)	(44,300)	(25,200)
Payments of obligations under finance leases	0	0	0
Proceeds from issuance of short-term debt	0
Other	0	0	0
Net cash provided by (used in) financing activities	(66,500)	(19,850)	(2,646)
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	0	0	0
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	0	0	0
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31		0	0
Less: Restricted cash		0
Cash and cash equivalents	0	0	0
Hawaiian Electric
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Depreciation of property, plant and equipment	409	402	399
Changes in assets and liabilities
Net cash provided by operating activities	(9,324)	131,873	167,150
Cash flows from investing activities
Capital expenditures	(214)	(21)	(224)
Other	(1,518)	610	1,662
Net cash used in investing activities	(116,436)	(15,199)	(50,331)
Cash flows from financing activities
Common stock dividends	0	(112,957)	(153,229)
Proceeds from issuance of common stock/capital contribution from parent	556,612	1,223	0
Proceeds from issuance of long-term debt	0	100,000	160,000
Repayment of long-term debt and funds transferred for repayment of long-term debt	0	(50,000)	(150,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	0	(49,683)	(4,315)
Proceeds from issuance of short-term debt	0	65,000	35,000
Other	0	(771)	(978)
Net cash provided by (used in) financing activities	553,538	25,441	(116,687)
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	427,778	142,115	132
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	142,726	611	479
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31	570,504	142,726	611
Less: Restricted cash	(6,320)	(6,216)	0
Cash and cash equivalents	564,184	136,510	611
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income (loss)	(1,225,282)	195,032	190,009
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Equity in earnings of subsidiaries	248,004	(44,809)	(47,493)
Common stock dividends received from subsidiaries		24,450	31,600
Depreciation of property, plant and equipment	167,909	164,150	158,725
Other amortization	23,606	17,692	16,708
Deferred income tax expense (benefit)	(393,025)	(851)	(33,648)
Gain/Loss on sale of receivables to BRWR	4,079
State refundable credit	(7,914)	(7,577)	(7,375)
Bad debt expense	2,838	5,565	4,175
Allowance for equity funds used during construction	(10,853)	(11,721)	(8,464)
Other	(6,270)	380	(65)
Changes in assets and liabilities
Decrease (increase) in accounts receivable	22,897	(83,401)	(74,067)
Decrease (increase) in accrued unbilled revenues	57,281	8	(43,972)
Decrease in fuel oil stock	37,427	45,114	(82,158)
Decrease (increase) in materials and supplies	(5,269)	(16,204)	(6,124)
Increase in regulatory assets	(4,608)	(6,616)	28,076
Increase in regulatory liabilities	38,413	48,833	28,621
Increase (decrease) in accounts payable	9,879	13,988	18,657
Change in prepaid and accrued income taxes, tax credits and revenue taxes	(14,192)	4,314	77,903
Change in defined benefit pension and other postretirement benefit plans asset/liability	(6,334)	(5,653)	(3,545)
Increase in wildfire tort-related claims	1,457,000	75,000
Change in other assets and liabilities	(52,774)	(12,990)	(17,884)
Net cash provided by operating activities	342,812	404,704	229,679
Cash flows from investing activities
Capital expenditures	(197,142)	(276,600)	(223,223)
Advances from (to) affiliates	(46,700)	(70,500)	1,000
Other	(10,169)	4,118	(5,687)
Net cash used in investing activities	(254,011)	(342,982)	(227,910)
Cash flows from financing activities
Common stock dividends	(26,000)	(129,000)	(125,900)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(1,995)	(1,080)	(1,080)
Proceeds from issuance of common stock/capital contribution from parent	270		13,101
Proceeds from issuance of long-term debt		300,000	40,000
Repayment of long-term debt and funds transferred for repayment of long-term debt	(74,000)	(50,000)	(40,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	0	(114,167)	114,167
Payments of obligations under finance leases	(3,487)	(2,728)	(670)
Proceeds from issuance of short-term debt	50,000
Other	(6,977)	(571)	(241)
Net cash provided by (used in) financing activities	(62,189)	2,454	(623)
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	26,612	64,176	1,146
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	91,755	27,579	26,433
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31		91,755	27,579
Less: Restricted cash		(2,000)
Cash and cash equivalents	118,367	89,755	27,579
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income (loss)	(115,880)	29,041	22,350
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Equity in earnings of subsidiaries	0	0	0
Common stock dividends received from subsidiaries		0	0
Depreciation of property, plant and equipment	43,855	42,541	41,404
Other amortization	4,958	5,003	4,996
Deferred income tax expense (benefit)	(47,550)	(296)	(4,040)
Gain/Loss on sale of receivables to BRWR	821
State refundable credit	(1,848)	(1,782)	(1,734)
Bad debt expense	476	1,353	1,073
Allowance for equity funds used during construction	(1,189)	(1,411)	(898)
Other	(50)	(46)	(50)
Changes in assets and liabilities
Decrease (increase) in accounts receivable	(13,175)	(7,398)	(11,644)
Decrease (increase) in accrued unbilled revenues	20,989	(1,308)	(4,289)
Decrease in fuel oil stock	4,205	(1,004)	(4,150)
Decrease (increase) in materials and supplies	(1,109)	(4,614)	(56)
Increase in regulatory assets	(5,346)	5,501	1,546
Increase in regulatory liabilities	6,597	(1,176)	7,977
Increase (decrease) in accounts payable	(1,687)	5,998	3,294
Change in prepaid and accrued income taxes, tax credits and revenue taxes	(2,325)	2,407	11,117
Change in defined benefit pension and other postretirement benefit plans asset/liability	(1,521)	(1,348)	(626)
Increase in wildfire tort-related claims	191,500	0
Change in other assets and liabilities	(4,035)	2,056	213
Net cash provided by operating activities	77,686	73,517	66,483
Cash flows from investing activities
Capital expenditures	(51,209)	(63,889)	(49,004)
Advances from (to) affiliates	0	4,500	(4,500)
Other	679	932	760
Net cash used in investing activities	(50,530)	(58,457)	(52,744)
Cash flows from financing activities
Common stock dividends	0	(13,425)	(16,400)
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	(534)	(534)
Proceeds from issuance of common stock/capital contribution from parent	0		6,023
Proceeds from issuance of long-term debt		25,000	10,000
Repayment of long-term debt and funds transferred for repayment of long-term debt	(5,000)	(20,000)	(12,000)
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	0	0	(1,000)
Payments of obligations under finance leases	(632)	(400)	0
Proceeds from issuance of short-term debt	0
Other	(648)	(135)	(62)
Net cash provided by (used in) financing activities	(6,280)	(9,494)	(13,973)
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	20,876	5,566	(234)
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	10,658	5,092	5,326
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31		10,658	5,092
Less: Restricted cash		0
Cash and cash equivalents	31,534	10,658	5,092
Maui Electric | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income (loss)	(134,491)	16,683	26,058
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Equity in earnings of subsidiaries	0	0	0
Common stock dividends received from subsidiaries		0	0
Depreciation of property, plant and equipment	39,378	37,014	35,295
Other amortization	3,264	3,795	3,616
Deferred income tax expense (benefit)	(41,049)	2,586	(3,727)
Gain/Loss on sale of receivables to BRWR	670
State refundable credit	(2,152)	(1,966)	(1,890)
Bad debt expense	1,406	1,243	779
Allowance for equity funds used during construction	(1,744)	(2,032)	(1,212)
Other	9	126	(24)
Changes in assets and liabilities
Decrease (increase) in accounts receivable	1,570	(29,301)	(10,680)
Decrease (increase) in accrued unbilled revenues	22,633	(1,748)	(5,762)
Decrease in fuel oil stock	7,702	(817)	(1,144)
Decrease (increase) in materials and supplies	2,345	(14,047)	(1,511)
Increase in regulatory assets	(12,789)	(9,498)	4,978
Increase in regulatory liabilities	3,423	6,813	8,290
Increase (decrease) in accounts payable	1,452	468	404
Change in prepaid and accrued income taxes, tax credits and revenue taxes	(8,614)	(4,843)	14,178
Change in defined benefit pension and other postretirement benefit plans asset/liability	(1,363)	(1,185)	(657)
Increase in wildfire tort-related claims	191,500	0
Change in other assets and liabilities	(23,280)	17,305	(3,623)
Net cash provided by operating activities	49,870	20,596	63,368
Cash flows from investing activities
Capital expenditures	(81,128)	(98,286)	(57,230)
Advances from (to) affiliates	0	21,700	(21,700)
Other	(1,011)	1,126	1,253
Net cash used in investing activities	(82,139)	(75,460)	(77,677)
Cash flows from financing activities
Common stock dividends	0	(11,025)	(15,200)
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	(381)	(381)
Proceeds from issuance of common stock/capital contribution from parent	0		3,023
Proceeds from issuance of long-term debt		25,000	10,000
Repayment of long-term debt and funds transferred for repayment of long-term debt	(2,000)	(30,000)	0
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	46,700	70,500	0
Payments of obligations under finance leases	0	0	0
Proceeds from issuance of short-term debt	0
Other	(1,562)	(137)	(61)
Net cash provided by (used in) financing activities	43,138	53,957	(2,619)
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	10,869	(907)	(16,928)
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	5,587	6,494	23,422
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31		5,587	6,494
Less: Restricted cash		0
Cash and cash equivalents	16,456	5,587	6,494
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Company, Inc. and Subsidiaries
Cash flows from operating activities
Net income (loss)	3,282	0	0
Adjustments to reconcile net income (loss) to net cash provided by operating activities-continuing operations
Equity in earnings of subsidiaries	0	0	0
Common stock dividends received from subsidiaries		0	0
Depreciation of property, plant and equipment	0	0	0
Other amortization	0	0	0
Deferred income tax expense (benefit)	0	0	0
Gain/Loss on sale of receivables to BRWR	(5,570)
State refundable credit	0	0	0
Bad debt expense	0	0	0
Allowance for equity funds used during construction	0	0	0
Other	0	0	0
Changes in assets and liabilities
Decrease (increase) in accounts receivable	(95,382)	0	0
Decrease (increase) in accrued unbilled revenues	(93,342)	0	0
Decrease in fuel oil stock	0	0	0
Decrease (increase) in materials and supplies	0	0	0
Increase in regulatory assets	0	0	0
Increase in regulatory liabilities	0	0
Increase (decrease) in accounts payable	0	0	0
Change in prepaid and accrued income taxes, tax credits and revenue taxes	1,138	0	0
Change in defined benefit pension and other postretirement benefit plans asset/liability	0	0	0
Increase in wildfire tort-related claims	0	0
Change in other assets and liabilities	187,788	0	0
Net cash provided by operating activities	(2,086)	0	0
Cash flows from investing activities
Capital expenditures	0	0	0
Advances from (to) affiliates	0	0	0
Other	0	0	0
Net cash used in investing activities	0	0	0
Cash flows from financing activities
Common stock dividends	0	0	0
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	0	0
Proceeds from issuance of common stock/capital contribution from parent	19,800		0
Proceeds from issuance of long-term debt		0	0
Repayment of long-term debt and funds transferred for repayment of long-term debt	0	0	0
Net increase (decrease) in short-term borrowings from non-affiliates and affiliate with original maturities of three months or less	0	0	0
Payments of obligations under finance leases	0	0	0
Proceeds from issuance of short-term debt	0
Other	0	0	0
Net cash provided by (used in) financing activities	19,800	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash from discontinued operations	17,714	0	0
Cash, cash equivalents and restricted cash, including cash from discontinued operations, January 1	77	77	77
Cash, cash equivalents and restricted cash, including cash from discontinued operations, December 31		77	77
Less: Restricted cash		0
Cash and cash equivalents	$ 17,791	$ 77	$ 77