Retirement benefits - Components of Net Periodic Benefit Cost for Consolidated HEI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension benefits
Defined Benefit Plan
Service cost	$ 11,418	$ 18,831	$ 34,210	$ 58,478
Interest cost	26,022	20,274	77,265	59,895
Expected return on plan assets	(35,238)	(35,163)	(105,630)	(105,827)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain) losses	138	7,782	515	20,376
Net periodic pension/benefit cost (return)	2,340	11,724	6,360	32,922
Impact of PUC D&Os	17,663	8,758	53,929	27,861
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	20,003	20,482	60,289	60,783
Other benefits
Defined Benefit Plan
Service cost	385	624	1,072	1,937
Interest cost	2,075	1,593	6,389	4,868
Expected return on plan assets	(3,426)	(3,394)	(10,236)	(10,189)
Amortization of net prior period gain	(218)	(232)	(656)	(696)
Amortization of net actuarial (gain) losses	(518)	(3)	(1,416)	(9)
Net periodic pension/benefit cost (return)	(1,702)	(1,412)	(4,847)	(4,089)
Impact of PUC D&Os	1,536	1,289	4,385	3,725
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	(166)	(123)	(462)	(364)
Hawaiian Electric Company, Inc. and Subsidiaries | Pension benefits
Defined Benefit Plan
Service cost	11,071	18,248	33,108	56,883
Interest cost	24,116	18,850	71,513	55,773
Expected return on plan assets	(33,029)	(33,314)	(98,972)	(100,405)
Amortization of net prior period gain	0	0	0	0
Amortization of net actuarial (gain) losses	(16)	7,519	21	19,769
Net periodic pension/benefit cost (return)	2,142	11,303	5,670	32,020
Impact of PUC D&Os	17,663	8,758	53,929	27,861
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	19,805	20,061	59,599	59,881
Hawaiian Electric Company, Inc. and Subsidiaries | Other benefits
Defined Benefit Plan
Service cost	380	617	1,060	1,915
Interest cost	1,981	1,525	6,107	4,670
Expected return on plan assets	(3,374)	(3,343)	(10,081)	(10,035)
Amortization of net prior period gain	(218)	(232)	(654)	(694)
Amortization of net actuarial (gain) losses	(503)	0	(1,370)	0
Net periodic pension/benefit cost (return)	(1,734)	(1,433)	(4,938)	(4,144)
Impact of PUC D&Os	1,536	1,289	4,385	3,725
Net periodic pension/benefit cost (return) (adjusted for impact of PUC D&Os)	$ (198)	$ (144)	$ (553)	$ (419)