SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements, Captions [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
Aggregate principal payments, fiscal year maturity:
2024	110,000
2025	153,000
2026	435,000
2027	274,000
2028	51,000
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027
Condensed Financial Statements, Captions [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
Condensed Financial Statements, Captions [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
Condensed Financial Statements, Captions [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
Condensed Financial Statements, Captions [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
Condensed Financial Statements, Captions [Line Items]
Line of credit facility basis point spread	0.10%
Hawaiian Electric
Condensed Financial Statements, Captions [Line Items]
Less unamortized debt issuance costs and debt discount	$ (2,440)	$ (2,995)
Less current portion long-term debt, net of unamortized debt issuance cost	(49,962)	0
Long-term debt, net—other than bank	730,598	782,005
Aggregate principal payments, fiscal year maturity:
2024	50,000
2025	16,000
2026	157,000
2027	193,000
2028	0
Thereafter	367,000
Cash dividends paid	427,000	168,000	$ 168,000
HEI DRIP transaction	0	5,000	0
Hawaiian Electric | American Savings Bank (ASB)
Aggregate principal payments, fiscal year maturity:
Cash dividends paid	401,000
Hawaiian Electric | ASB Hawaii, Inc. | Consolidated subsidiary
Aggregate principal payments, fiscal year maturity:
Accounts receivable reduction	1,600	2,300	1,900
HEI notes payable increase to ASHI	1,600	2,300	$ 1,900
Hawaiian Electric | Mahipapa, LLC
Aggregate principal payments, fiscal year maturity:
Notes and interest receivable forgiven	9,600
Hawaiian Electric | HEI 4.58% senior notes, due 2025
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 50,000	50,000
Debt instrument, stated interest rate (as percent)	4.58%
Hawaiian Electric | HEI 4.72% senior notes, due 2028
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 100,000	100,000
Debt instrument, stated interest rate (as percent)	4.72%
Hawaiian Electric | HEI 2.82% senior notes, due 2028
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 24,000	24,000
Debt instrument, stated interest rate (as percent)	2.82%
Hawaiian Electric | HEI 2.48% senior notes, due 2028
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 30,000	30,000
Debt instrument, stated interest rate (as percent)	2.48%
Hawaiian Electric | HEI 6.04% senior notes, due 2028
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 39,000	39,000
Debt instrument, stated interest rate (as percent)	6.04%
Hawaiian Electric | HEI 2.98% senior notes, due 2030
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 50,000	50,000
Debt instrument, stated interest rate (as percent)	2.98%
Hawaiian Electric | HEI 3.15% senior notes, due 2031
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 51,000	51,000
Debt instrument, stated interest rate (as percent)	3.15%
Hawaiian Electric | HEI 2.78% senior notes, due 2031
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 25,000	25,000
Debt instrument, stated interest rate (as percent)	2.78%
Hawaiian Electric | HEI 2.98% senior notes, due 2032
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 30,000	30,000
Debt instrument, stated interest rate (as percent)	2.98%
Hawaiian Electric | HEI 5.43% senior notes, due 2032
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 75,000	75,000
Debt instrument, stated interest rate (as percent)	5.43%
Hawaiian Electric | HEI 6.10% senior notes, due 2033
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 61,000	61,000
Hawaiian Electric | HEI 5.43% senior notes, due 2034
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 35,000	35,000
Debt instrument, stated interest rate (as percent)	5.43%
Hawaiian Electric | HEI 3.74% senior notes, due 2051
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 20,000	20,000
Debt instrument, stated interest rate (as percent)	3.74%
Hawaiian Electric | HEI 3.94% senior notes, due 2052
Condensed Financial Statements, Captions [Line Items]
Gross long-term debt	$ 20,000	$ 20,000
Debt instrument, stated interest rate (as percent)	3.94%