Segment financial information - Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment financial information
Revenues	$ 746,392	$ 795,417	$ 1,490,462	$ 1,587,431
Depreciation and amortization	76,105	73,204	152,667	146,833
Interest income	7,579	3,134	20,202	6,267
Interest expense, net	27,256	32,400	61,468	63,991
Income (loss) from continuing operations before income taxes	39,975	(1,685,174)	73,514	(1,656,718)
Income taxes (benefit)	13,417	(435,950)	19,812	(429,155)
Income (loss) from continuing operations	26,558	(1,249,224)	53,702	(1,227,563)
Preferred stock dividends of Hawaiian Electric	473	473	946	946
Income (loss) from continuing operations for common stock	26,085	(1,249,697)	52,756	(1,228,509)
Capital expenditures			161,493	178,926
Total assets	8,324,861		8,324,861		$ 8,931,416
All Other
Segment financial information
Revenues	3,910	3,086	9,614	6,522
Depreciation and amortization	2,474	2,876	5,483	6,127
Interest income	6,364	1,682	17,006	3,383
Interest expense, net	5,550	10,983	17,310	22,589
Income (loss) from continuing operations before income taxes	(10,294)	(26,521)	(38,274)	(48,965)
Income taxes (benefit)	2,797	(6,192)	(4,012)	(10,577)
Income (loss) from continuing operations	(13,091)	(20,329)	(34,262)	(38,388)
Preferred stock dividends of Hawaiian Electric	(26)	(26)	(52)	(52)
Income (loss) from continuing operations for common stock	(13,065)	(20,303)	(34,210)	(38,336)
Capital expenditures			1,543	10,726
Total assets	441,202		441,202		1,317,812
Electric utility
Segment financial information
Revenues	742,482	792,331	1,480,848	1,580,909
Electric utility | Operating Segments
Segment financial information
Revenues	742,482	792,331	1,480,848	1,580,909
Depreciation and amortization	73,631	70,328	147,184	140,706
Interest income	1,215	1,452	3,196	2,884
Interest expense, net	21,706	21,417	44,158	41,402
Income (loss) from continuing operations before income taxes	50,269	(1,658,653)	111,788	(1,607,753)
Income taxes (benefit)	10,620	(429,758)	23,824	(418,578)
Income (loss) from continuing operations	39,649	(1,228,895)	87,964	(1,189,175)
Preferred stock dividends of Hawaiian Electric	499	499	998	998
Income (loss) from continuing operations for common stock	39,150	$ (1,229,394)	86,966	(1,190,173)
Capital expenditures			159,950	$ 168,200
Total assets	$ 7,883,659		$ 7,883,659		$ 7,613,604