Segment financial information - Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Segment financial information
Revenues	$ 790,610	$ 833,239	$ 2,281,072	$ 2,420,670
Depreciation and amortization	73,956	73,312	226,623	220,145
Interest income	6,960	3,662	27,162	9,929
Interest expense, net	26,211	32,085	87,679	96,076
Income (loss) from continuing operations before income taxes	39,946	(172,663)	113,460	(1,829,381)
Income tax expense (benefit)	8,728	(49,954)	28,540	(479,109)
Income (loss) from continuing operations	31,218	(122,709)	84,920	(1,350,272)
Preferred stock dividends of Hawaiian Electric	471	471	1,417	1,417
Income (loss) from continuing operations for common stock	30,747	(123,180)	83,503	(1,351,689)
Capital expenditures			255,450	256,920
Total assets	8,813,636		8,813,636		$ 8,931,416
All Other
Segment financial information
Revenues	3,182	3,622	12,796	10,144
Depreciation and amortization	221	2,764	5,704	8,891
Interest income	5,499	1,991	22,505	5,374
Interest expense, net	4,097	11,862	21,407	34,451
Income (loss) from continuing operations before income taxes	(8,513)	(55,137)	(46,787)	(104,102)
Income tax expense (benefit)	(2,245)	(14,515)	(6,257)	(25,092)
Income (loss) from continuing operations	(6,268)	(40,622)	(40,530)	(79,010)
Preferred stock dividends of Hawaiian Electric	(27)	(27)	(79)	(79)
Income (loss) from continuing operations for common stock	(6,241)	(40,595)	(40,451)	(78,931)
Capital expenditures			1,523	12,620
Total assets	422,677		422,677		1,317,812
Electric utility
Segment financial information
Revenues	787,428	829,617	2,268,276	2,410,526
Electric utility | Operating Segments
Segment financial information
Revenues	787,428	829,617	2,268,276	2,410,526
Depreciation and amortization	73,735	70,548	220,919	211,254
Interest income	1,461	1,671	4,657	4,555
Interest expense, net	22,114	20,223	66,272	61,625
Income (loss) from continuing operations before income taxes	48,459	(117,526)	160,247	(1,725,279)
Income tax expense (benefit)	10,973	(35,439)	34,797	(454,017)
Income (loss) from continuing operations	37,486	(82,087)	125,450	(1,271,262)
Preferred stock dividends of Hawaiian Electric	498	498	1,496	1,496
Income (loss) from continuing operations for common stock	36,988	$ (82,585)	123,954	(1,272,758)
Capital expenditures			253,927	$ 244,300
Total assets	$ 8,390,959		$ 8,390,959		$ 7,613,604