Consolidated Statements of Capitalization - HECO (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Common stock, authorized shares (in shares)	200,000,000	200,000,000
Common stock, outstanding shares (in shares)	109,181,124	108,973,328
Hawaiian Electric Company, Inc. and Subsidiaries
Common stock, par value (in dollars per share)	$ 6.667	$ 6.667
Common stock, authorized shares (in shares)	50,000,000	50,000,000
Common stock, outstanding shares (in shares)	17,324,376	17,048,783
Shares outstanding	1,234,657	1,234,657
Hawaiian Electric Company, Inc. and Subsidiaries | Special Purpose Revenue Bonds | 3.50%, Series 2019, due 2049
Debt instrument, stated interest rate	3.50%
Hawaiian Electric Company, Inc. and Subsidiaries | Special Purpose Revenue Bonds | 3.20%, Refunding series 2019, due 2039
Debt instrument, stated interest rate	3.20%
Hawaiian Electric Company, Inc. and Subsidiaries | Special Purpose Revenue Bonds | 3.10% Refunding Series 2017A Due 2026
Debt instrument, stated interest rate	3.10%
Hawaiian Electric Company, Inc. and Subsidiaries | Special Purpose Revenue Bonds | 4.00% Refunding Series 2017B, Due 2037
Debt instrument, stated interest rate	4.00%
Hawaiian Electric Company, Inc. and Subsidiaries | Special Purpose Revenue Bonds | 3.25% Refunding Series 2015 SPRBs due 2025
Debt instrument, stated interest rate	3.25%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.38%, Series 2018A, due 2028
Debt instrument, stated interest rate	4.38%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.53%, Series 2018B, due 2033
Debt instrument, stated interest rate	4.53%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.72%, Series 2018C, due 2048
Debt instrument, stated interest rate	4.72%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.31%, Series 2017A, due 2047
Debt instrument, stated interest rate	4.31%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.21%, Series 2019A, due 2034
Debt instrument, stated interest rate	4.21%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.54%, Series 2016A, due 2046
Debt instrument, stated interest rate	4.54%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 5.23%, Series 2015A, due 2045
Debt instrument, stated interest rate	5.23%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 3.83%, Series 2013A, due 2020 - paid in 2020
Debt instrument, stated interest rate	3.83%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.45%, Series 2013A and 2013B, due 2022
Debt instrument, stated interest rate	4.45%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.84%, Series 2013A, 2013B and 2013C, due 2027
Debt instrument, stated interest rate	4.84%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 5.65%, Series 2013B and 2013C, due 2043
Debt instrument, stated interest rate	5.65%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.03%, Series 2012B, due 2020 - paid in 2020
Debt instrument, stated interest rate	4.03%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.55%, Series 2012B and 2012C, due 2023
Debt instrument, stated interest rate	4.55%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.72%, Series 2012D, due 2029
Debt instrument, stated interest rate	4.72%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 5.39%, Series 2012E, due 2042
Debt instrument, stated interest rate	5.39%
Hawaiian Electric Company, Inc. and Subsidiaries | Senior notes | 4.53%, Series 2012F, due 2032
Debt instrument, stated interest rate	4.53%
Hawaiian Electric Company, Inc. and Subsidiaries | Preferred Stock $20 Par Value
Preferred stock, par value (in dollars per share)	$ 20	$ 20
Preferred stock, Authorized shares	5,000,000	5,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Preferred Stock $100 Par Value
Preferred stock, par value (in dollars per share)	$ 100	$ 100
Preferred stock, Authorized shares	7,000,000	7,000,000
Hawaiian Electric | Series C, 4.25% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	150,000	150,000
Preferred stock, stated dividend rate	4.25%	4.25%
Hawaiian Electric | Series D, 5.00% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	50,000	50,000
Preferred stock, stated dividend rate	5.00%	5.00%
Hawaiian Electric | Series E, 5.00% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	150,000	150,000
Preferred stock, stated dividend rate	5.00%	5.00%
Hawaiian Electric | Series H, 5.25% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	250,000	250,000
Preferred stock, stated dividend rate	5.25%	5.25%
Hawaiian Electric | Series I, 5.00% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	89,657	89,657
Preferred stock, stated dividend rate	5.00%	5.00%
Hawaiian Electric | Series J, 4.75% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	250,000	250,000
Preferred stock, stated dividend rate	4.75%	4.75%
Hawaiian Electric | Series K, 4.65% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 20
Shares outstanding	175,000	175,000
Preferred stock, stated dividend rate	4.65%	4.65%
HELCO | Series G, 7.625% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 100
Shares outstanding	70,000	70,000
Preferred stock, stated dividend rate	7.625%	7.625%
Maui Electric | Series H, 7.625% Preferred Stock
Preferred stock, par value (in dollars per share)	$ 100
Shares outstanding	50,000	50,000
Preferred stock, stated dividend rate	7.625%	7.625%