Long-term debt - Schedule of Long-Term Debt and Maturities (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 01, 2023	Feb. 29, 2024	Dec. 31, 2024 USD ($) MW	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Less unamortized debt issuance costs and debt discount			$ (6,681)	$ (8,097)
Less current portion long-term debt, net of unamortized debt issuance cost			(109,171)	(16,496)
Long-term debt, net—other than bank			2,690,387	2,825,933
Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Gross long-term debt			1,908,000	1,942,000
Less current portion long-term debt, net of unamortized debt issuance cost			(47,000)	0
Long-term debt of Utilities, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Long-term debt, net—other than bank			1,901,214	1,934,277
Senior notes | Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Gross long-term debt			1,200,000	1,200,000
Senior notes | HEI 4.58% senior notes, due 2025
Debt Instrument [Line Items]
Gross long-term debt			$ 50,000	50,000
Debt instrument, stated interest rate (as percent)			4.58%
Senior notes | HEI 4.72% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt			$ 100,000	100,000
Debt instrument, stated interest rate (as percent)			4.72%
Senior notes | HEI 2.82% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt			$ 24,000	24,000
Debt instrument, stated interest rate (as percent)			2.82%
Senior notes | HEI 2.48% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt			$ 30,000	30,000
Debt instrument, stated interest rate (as percent)			2.48%
Senior notes | HEI 6.04% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt			$ 39,000	39,000
Debt instrument, stated interest rate (as percent)			6.04%
Senior notes | HEI 2.98% senior notes, due 2030
Debt Instrument [Line Items]
Gross long-term debt			$ 50,000	50,000
Debt instrument, stated interest rate (as percent)			2.98%
Senior notes | HEI 3.15% senior notes, due 2031
Debt Instrument [Line Items]
Gross long-term debt			$ 51,000	51,000
Debt instrument, stated interest rate (as percent)			3.15%
Senior notes | HEI 2.78% senior notes, due 2031
Debt Instrument [Line Items]
Gross long-term debt			$ 25,000	25,000
Debt instrument, stated interest rate (as percent)			2.78%
Senior notes | HEI 2.98% senior notes, due 2032
Debt Instrument [Line Items]
Gross long-term debt			$ 30,000	30,000
Debt instrument, stated interest rate (as percent)			2.98%
Senior notes | HEI 5.43% senior notes, due 2032
Debt Instrument [Line Items]
Gross long-term debt			$ 75,000	75,000
Debt instrument, stated interest rate (as percent)			5.43%
Senior notes | HEI 6.10% senior notes, due 2033
Debt Instrument [Line Items]
Gross long-term debt			$ 61,000	61,000
Debt instrument, stated interest rate (as percent)			6.10%
Senior notes | HEI 5.43% senior notes, due 2034
Debt Instrument [Line Items]
Gross long-term debt			$ 35,000	35,000
Debt instrument, stated interest rate (as percent)			5.43%
Senior notes | HEI 3.74% senior notes, due 2051
Debt Instrument [Line Items]
Gross long-term debt			$ 20,000	20,000
Debt instrument, stated interest rate (as percent)			3.74%
Senior notes | HEI 3.94% senior notes, due 2052
Debt Instrument [Line Items]
Gross long-term debt			$ 20,000	20,000
Debt instrument, stated interest rate (as percent)			3.94%
Senior notes | Hāmākua Energy 4.02% non-recourse notes, due 2030
Debt Instrument [Line Items]
Gross long-term debt			$ 39,026	44,855
Debt instrument, stated interest rate (as percent)			4.02%
Power produced by power plants (in megawatts) | MW			60
Debt collateralized by property, plant and equipment			$ 165,000
Term Loan | Mauō 5.07% non-recourse loan, due 2034 to 2035
Debt Instrument [Line Items]
Gross long-term debt			$ 20,795	16,962
Debt instrument, stated interest rate (as percent)			5.07%
Term Loan | Ka`ie`ie Waho 2.79% non-recourse loan, due 2031
Debt Instrument [Line Items]
Gross long-term debt			$ 8,517	9,727
Debt instrument, stated interest rate (as percent)			2.79%
Term Loan | Mahipapa 1.90% non-recourse loan, due 2034 to 2036
Debt Instrument [Line Items]
Gross long-term debt			$ 53,263	$ 53,743
Debt instrument, stated interest rate (as percent)			2.14%	1.90%
Term Loan | Mahipapa 5.625% non-recourse loan, due 2027
Debt Instrument [Line Items]
Gross long-term debt			$ 424	$ 578
Debt instrument, stated interest rate (as percent)			5.625%
Unsecured Debt | Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Gross long-term debt			$ 1,366,000	1,400,000
Unsecured Debt | Mauo SOFR + 1.475% loan, due 2024
Debt Instrument [Line Items]
Gross long-term debt			$ 0	$ 5,384
Line of credit facility basis point spread		1.70%
Unsecured Debt | Mauo SOFR + 1.475% loan, due 2024 | SOFR
Debt Instrument [Line Items]
Line of credit facility basis point spread			1.475%
Unsecured Debt | Mauo SOFR + 1.475% loan, due 2024 | Secured Overnight Financing Rate (SOFR), Excluding Replacement Rate Adjustment
Debt Instrument [Line Items]
Line of credit facility basis point spread	1.375%
Unsecured Debt | Mauo SOFR + 1.475% loan, due 2024 | Secured Overnight Financing Rate (SOFR), Replacement Rate Adjustment
Debt Instrument [Line Items]
Line of credit facility basis point spread	0.10%
Unsecured Debt | Floating Rate Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage (as percent)			4.91%	4.91%
Unsecured Debt | Fixed Rate Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage (as percent)			5.10%
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027
Debt Instrument [Line Items]
Gross long-term debt			$ 173,000	$ 175,000
Weighted average interest rate (as percent)			6.89%	7.19%
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027 | SOFR
Debt Instrument [Line Items]
Line of credit facility basis point spread			1.80%
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027 | Secured Overnight Financing Rate (SOFR) Excluding Sustainability Margin And Additional Adjustments
Debt Instrument [Line Items]
Line of credit facility basis point spread			1.75%
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027 | Secured Overnight Financing Rate (SOFR), Sustainability Margin Adjustment
Debt Instrument [Line Items]
Line of credit facility basis point spread			0.05%
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027 | Secured Overnight Financing Rate (SOFR), Additional Adjustment
Debt Instrument [Line Items]
Line of credit facility basis point spread			0.10%