Long-term debt - Schedule of Long-Term Debt and Maturities (Details) - USD ($)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Less unamortized debt issuance costs	$ (3,164,000)	$ (2,249,000)
Long-term debt, net—other than bank	2,321,937,000	2,119,129,000
Aggregate principal payments, fiscal year maturity:
2022	223,000,000
2023	163,000,000
2024	6,000,000
2025	104,000,000
2026	131,000,000
Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Gross long-term debt	1,684,000,000	1,569,000,000
Aggregate principal payments, fiscal year maturity:
2022	52,000,000
2023	100,000,000
2024	0
2025	47,000,000
2026	125,000,000
Special purpose revenue bonds issued on behalf of electric utility subsidiaries
Debt Instrument [Line Items]
Long-term debt, net—other than bank	1,676,402,000	1,561,302,000
Senior notes \| Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Gross long-term debt	1,142,000,000	1,027,000,000
Senior notes \| HEI 5.67% senior notes, due 2021
Debt Instrument [Line Items]
Gross long-term debt	$ 0	50,000,000
Debt instrument, stated interest rate	5.67%
Senior notes \| HEI 3.99% senior notes, due 2023
Debt Instrument [Line Items]
Gross long-term debt	$ 50,000,000	50,000,000
Debt instrument, stated interest rate	3.99%
Senior notes \| HEI 4.58% senior notes, due 2025
Debt Instrument [Line Items]
Gross long-term debt	$ 50,000,000	50,000,000
Debt instrument, stated interest rate	4.58%
Senior notes \| HEI 4.72% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 100,000,000	100,000,000
Debt instrument, stated interest rate	4.72%
Senior notes \| HEI 2.82% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 24,000,000	0
Debt instrument, stated interest rate	2.82%
Senior notes \| HEI 2.98% senior notes, due 2030
Debt Instrument [Line Items]
Gross long-term debt	$ 50,000,000	50,000,000
Debt instrument, stated interest rate	2.98%
Senior notes \| HEI 3.15% senior notes, due 2031
Debt Instrument [Line Items]
Gross long-term debt	$ 51,000,000	0
Debt instrument, stated interest rate	3.15%
Senior notes \| HEI 2.48% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 30,000,000	0
Debt instrument, stated interest rate	2.48%
Senior notes \| HEI 2.78% senior notes, due 2031
Debt Instrument [Line Items]
Gross long-term debt	$ 25,000,000	0
Debt instrument, stated interest rate	2.78%
Senior notes \| HEI 3.74% senior notes, due 2051
Debt Instrument [Line Items]
Gross long-term debt	$ 20,000,000	0
Debt instrument, stated interest rate	3.74%
Senior notes \| Hāmākua Energy 4.02% non-recourse notes, due 2030
Debt Instrument [Line Items]
Gross long-term debt	$ 52,166,000	56,030,000
Debt instrument, stated interest rate	4.02%
Term Loan \| HEI 2.99% term loan, due 2022
Debt Instrument [Line Items]
Gross long-term debt	$ 150,000,000	150,000,000
Debt instrument, stated interest rate	2.99%
Term Loan \| Mauō 4.90% non-recourse loan, due 2034
Debt Instrument [Line Items]
Gross long-term debt	$ 12,686,000	0
Debt instrument, stated interest rate	4.90%
Term Loan \| Ka`ie`ie Waho 2.79% non-recourse loan, due 2031
Debt Instrument [Line Items]
Gross long-term debt	$ 12,145,000	13,000,000
Debt instrument, stated interest rate	2.79%
Unsecured Debt \| Mauo LIBOR + 1.375% loan, due 2023
Debt Instrument [Line Items]
Gross long-term debt	$ 21,702,000	$ 41,046,000
Maximum aggregate principal amount	50,500,000
Paydown of loan balance, maximum balance	$ 7,000,000
Unsecured Debt \| Mauo LIBOR + 1.375% loan, due 2023 \| LIBOR
Debt Instrument [Line Items]
Line of credit facility basis point spread	1.375%

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