Shareholders' equity - Reclassification out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	$ (897,360)	$ (895,685)	$ (1,794,518)	$ (1,823,922)
Interest expense	32,400	29,832	63,991	58,630
Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	3,251	3,710	6,299	7,407
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	(792,331)	(794,191)	(1,580,909)	(1,624,552)
Total reclassifications	1,228,895	(45,798)	1,189,175	(93,306)
Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(46)	(44)	(95)	(89)
Amortization of unrealized holding losses on held-to-maturity securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	3,288	3,689	6,374	7,366
Net realized gains on derivatives qualifying as cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	(51)	(48)	(99)	(96)
Amortization of prior service credit and net gains recognized during the period in net periodic benefit cost | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(445)	(357)	(894)	(714)
Amortization of prior service credit and net gains recognized during the period in net periodic benefit cost | Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(505)	(470)	(1,013)	(940)
Impact of D&Os of the PUC included in regulatory assets | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	459	426	918	851
Impact of D&Os of the PUC included in regulatory assets | Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	$ 459	$ 426	$ 918	$ 851