Segment financial information - Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Segment financial information
Revenues	$ 938,383			$ 901,873			$ 2,732,901	$ 2,725,795
Income (loss) before income taxes	(149,234)			49,110			(1,837,245)	188,781
Income taxes (benefit)	(45,303)			7,521			(480,898)	36,915
Net income (loss)	(103,931)			41,589			(1,356,347)	151,866
Preferred stock dividends of Hawaiian Electric	471			471			1,417	1,417
Net income (loss) for common stock	(104,402)	$ (1,295,484)	$ 42,122	41,118	$ 54,610	$ 54,721	(1,357,764)	150,449
Total assets	17,731,228						17,731,228		$ 17,243,821
Electric utility
Segment financial information
Revenues	829,617			794,987			2,410,526	2,419,539
Income (loss) before income taxes	(117,526)			55,415			(1,725,279)	175,391
Income taxes (benefit)	(35,439)			11,456			(454,017)	38,126
Net income (loss)	(82,087)			43,959			(1,271,262)	137,265
Preferred stock dividends of Hawaiian Electric	498			498			1,496	1,496
Net income (loss) for common stock	(82,585)			43,461			(1,272,758)	135,769
Total assets	7,563,204						7,563,204		7,283,554
Bank
Segment financial information
Revenues	105,144			100,974			312,231	291,716
Income (loss) before income taxes	23,429			12,749			(7,864)	61,511
Income taxes (benefit)	4,651			1,384			(1,789)	11,380
Net income (loss)	18,778			11,365			(6,075)	50,131
Preferred stock dividends of Hawaiian Electric	0			0			0	0
Net income (loss) for common stock	18,778			11,365			(6,075)	50,131
Total assets	9,267,846						9,267,846		9,673,192
Other
Segment financial information
Revenues	3,622			5,912			10,144	14,540
Income (loss) before income taxes	(55,137)			(19,054)			(104,102)	(48,121)
Income taxes (benefit)	(14,515)			(5,319)			(25,092)	(12,591)
Net income (loss)	(40,622)			(13,735)			(79,010)	(35,530)
Preferred stock dividends of Hawaiian Electric	(27)			(27)			(79)	(79)
Net income (loss) for common stock	(40,595)			$ (13,708)			(78,931)	$ (35,451)
Total assets	$ 900,178						$ 900,178		$ 287,075