Electric utility segment - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Cash flows from operating activities
Net cash provided by (used in) operating activities	$ 350,911	$ 475,138
Cash flows from investing activities
Capital expenditures	(258,645)	(342,364)
Other	(1,142)	9,375
Net cash used in investing activities	(24,060)	(369,638)
Cash flows from financing activities
Common stock dividends	0	(112,957)
Proceeds from issuance of common stock	556,724	437
Proceeds from issuance of long-term debt	5,204	625,000
Net decrease in short-term borrowings with original maturities of three months or less	0	(137,650)
Other	(18,149)	(9,409)
Net cash provided by (used in) financing activities	151,855	371,866
Net increase in cash, cash equivalents and restricted cash	478,706	477,366
Cash, cash equivalents and restricted cash, beginning of period	694,574	204,927
Cash, cash equivalents and restricted cash, end of period	1,173,280	682,293
Less: Restricted cash	(13,645)	(15,164)	$ (15,028)
Cash and cash equivalents	1,159,635	667,129	679,546
Hawaiian Electric Consolidated
Cash flows from operating activities
Net cash provided by (used in) operating activities	322,648	406,111
Cash flows from investing activities
Capital expenditures	(244,300)	(334,497)
Advanced (to) from affiliates	0	0
Other	2,697	5,216
Net cash used in investing activities	(241,603)	(329,281)
Cash flows from financing activities
Common stock dividends	(26,000)	(96,750)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(1,496)	(1,496)
Proceeds from issuance of common stock	0
Proceeds from issuance of long-term debt	0	350,000
Net decrease in short-term borrowings with original maturities of three months or less	0	(87,967)
Payments of obligations under finance leases	(5,876)	(2,162)
Other	(6,126)	(843)
Net cash provided by (used in) financing activities	(39,498)	160,782
Net increase in cash, cash equivalents and restricted cash	41,547	237,612
Cash, cash equivalents and restricted cash, beginning of period	108,077	39,242
Cash, cash equivalents and restricted cash, end of period	149,624	276,854
Less: Restricted cash	(2,000)	(2,000)	(2,000)
Cash and cash equivalents	147,624	274,854	106,077
Consolidating adjustments | Hawaiian Electric Consolidated
Cash flows from operating activities
Net cash provided by (used in) operating activities	(2,082)	(24,450)
Cash flows from investing activities
Capital expenditures	0	0
Advanced (to) from affiliates	30,700	(26,200)
Other	21,882	0
Net cash used in investing activities	52,582	(26,200)
Cash flows from financing activities
Common stock dividends	0	24,450
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	0
Proceeds from issuance of common stock	(19,800)
Proceeds from issuance of long-term debt		0
Net decrease in short-term borrowings with original maturities of three months or less	(30,700)	26,200
Payments of obligations under finance leases	0	0
Other	0	0
Net cash provided by (used in) financing activities	(50,500)	50,650
Net increase in cash, cash equivalents and restricted cash	0	0
Cash, cash equivalents and restricted cash, beginning of period	0	0
Cash, cash equivalents and restricted cash, end of period	0	0
Less: Restricted cash	0	0	0
Cash and cash equivalents	0	0	0
Hawaiian Electric
Cash flows from financing activities
Cash and cash equivalents	677,700
Hawaiian Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Cash flows from operating activities
Net cash provided by (used in) operating activities	237,155	336,248
Cash flows from investing activities
Capital expenditures	(141,000)	(217,276)
Advanced (to) from affiliates	(30,700)	0
Other	(18,696)	3,179
Net cash used in investing activities	(190,396)	(214,097)
Cash flows from financing activities
Common stock dividends	(26,000)	(96,750)
Preferred stock dividends of Hawaiian Electric and subsidiaries	(1,496)	(810)
Proceeds from issuance of common stock	0
Proceeds from issuance of long-term debt		300,000
Net decrease in short-term borrowings with original maturities of three months or less	0	(114,167)
Payments of obligations under finance leases	(5,233)	(1,914)
Other	(4,393)	(571)
Net cash provided by (used in) financing activities	(37,122)	85,788
Net increase in cash, cash equivalents and restricted cash	9,637	207,939
Cash, cash equivalents and restricted cash, beginning of period	91,755	27,579
Cash, cash equivalents and restricted cash, end of period	101,392	235,518
Less: Restricted cash	(2,000)	(2,000)	(2,000)
Cash and cash equivalents	99,392	233,518	89,755
Hawaii Electric Light | Reportable Legal Entities | Hawaiian Electric Consolidated
Cash flows from operating activities
Net cash provided by (used in) operating activities	54,936	59,029
Cash flows from investing activities
Capital expenditures	(39,405)	(47,609)
Advanced (to) from affiliates	0	4,500
Other	523	912
Net cash used in investing activities	(38,882)	(42,197)
Cash flows from financing activities
Common stock dividends	0	(13,425)
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	(400)
Proceeds from issuance of common stock	0
Proceeds from issuance of long-term debt		25,000
Net decrease in short-term borrowings with original maturities of three months or less	0	0
Payments of obligations under finance leases	(470)	(248)
Other	(508)	(135)
Net cash provided by (used in) financing activities	(978)	10,792
Net increase in cash, cash equivalents and restricted cash	15,076	27,624
Cash, cash equivalents and restricted cash, beginning of period	10,658	5,092
Cash, cash equivalents and restricted cash, end of period	25,734	32,716
Less: Restricted cash	0	0	0
Cash and cash equivalents	25,734	32,716	10,658
Maui Electric | Reportable Legal Entities | Hawaiian Electric Consolidated
Cash flows from operating activities
Net cash provided by (used in) operating activities	41,851	35,284
Cash flows from investing activities
Capital expenditures	(63,895)	(69,612)
Advanced (to) from affiliates	0	21,700
Other	(1,012)	1,125
Net cash used in investing activities	(64,907)	(46,787)
Cash flows from financing activities
Common stock dividends	0	(11,025)
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	(286)
Proceeds from issuance of common stock	0
Proceeds from issuance of long-term debt		25,000
Net decrease in short-term borrowings with original maturities of three months or less	30,700	0
Payments of obligations under finance leases	(173)	0
Other	(1,225)	(137)
Net cash provided by (used in) financing activities	29,302	13,552
Net increase in cash, cash equivalents and restricted cash	6,246	2,049
Cash, cash equivalents and restricted cash, beginning of period	5,587	6,494
Cash, cash equivalents and restricted cash, end of period	11,833	8,543
Less: Restricted cash	0	0	0
Cash and cash equivalents	11,833	8,543	5,587
Other subsidiaries | Reportable Legal Entities | Hawaiian Electric Consolidated
Cash flows from operating activities
Net cash provided by (used in) operating activities	(9,212)	0
Cash flows from investing activities
Capital expenditures	0	0
Advanced (to) from affiliates	0	0
Other	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities
Common stock dividends	0	0
Preferred stock dividends of Hawaiian Electric and subsidiaries	0	0
Proceeds from issuance of common stock	19,800
Proceeds from issuance of long-term debt		0
Net decrease in short-term borrowings with original maturities of three months or less	0	0
Payments of obligations under finance leases	0	0
Other	0	0
Net cash provided by (used in) financing activities	19,800	0
Net increase in cash, cash equivalents and restricted cash	10,588	0
Cash, cash equivalents and restricted cash, beginning of period	77	77
Cash, cash equivalents and restricted cash, end of period	10,665	77
Less: Restricted cash	0	0	0
Cash and cash equivalents	$ 10,665	$ 77	$ 77