Segment financial information - Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment financial information
Revenues	$ 897,360		$ 895,685		$ 1,794,518	$ 1,823,922
Income (loss) before income taxes	(1,742,280)		69,367		(1,688,011)	139,671
Income taxes (benefit)	(447,269)		14,284		(435,595)	29,394
Net income (loss)	(1,295,011)		55,083		(1,252,416)	110,277
Preferred stock dividends of Hawaiian Electric	473		473		946	946
Net income (loss) for common stock	(1,295,484)	$ 42,122	54,610	$ 54,721	(1,253,362)	109,331
Total assets	17,055,414				17,055,414		$ 17,243,821
Electric utility
Segment financial information
Revenues	792,331		794,191		1,580,909	1,624,552
Income (loss) before income taxes	(1,658,653)		58,868		(1,607,753)	119,976
Income taxes (benefit)	(429,758)		13,070		(418,578)	26,670
Net income (loss)	(1,228,895)		45,798		(1,189,175)	93,306
Preferred stock dividends of Hawaiian Electric	499		499		998	998
Net income (loss) for common stock	(1,229,394)		45,299		(1,190,173)	92,308
Total assets	7,398,898				7,398,898		7,283,554
Bank
Segment financial information
Revenues	101,943		96,885		207,087	190,742
Income (loss) before income taxes	(57,106)		25,055		(31,293)	48,762
Income taxes (benefit)	(11,319)		4,851		(6,440)	9,996
Net income (loss)	(45,787)		20,204		(24,853)	38,766
Preferred stock dividends of Hawaiian Electric	0		0		0	0
Net income (loss) for common stock	(45,787)		20,204		(24,853)	38,766
Total assets	9,280,805				9,280,805		9,673,192
Other
Segment financial information
Revenues	3,086		4,609		6,522	8,628
Income (loss) before income taxes	(26,521)		(14,556)		(48,965)	(29,067)
Income taxes (benefit)	(6,192)		(3,637)		(10,577)	(7,272)
Net income (loss)	(20,329)		(10,919)		(38,388)	(21,795)
Preferred stock dividends of Hawaiian Electric	(26)		(26)		(52)	(52)
Net income (loss) for common stock	(20,303)		$ (10,893)		(38,336)	$ (21,743)
Total assets	$ 375,711				$ 375,711		$ 287,075