Electric utility segment Cumulative Preferred Stock (Details)	Dec. 31, 2015 $ / shares
HECO | Multiple Series Preferred Stock
Class of Stock [Line Items]
Voluntary liquidation price (in US$ per share)	$ 20
Redemption price (in US$ per share)	21
HECO | Series I Preferred Stock
Class of Stock [Line Items]
Voluntary liquidation price (in US$ per share)	20
Redemption price (in US$ per share)	20
Hawaii Electric Light Company, Inc. (HELCO) | Series G Preferred Stock
Class of Stock [Line Items]
Voluntary liquidation price (in US$ per share)	100
Redemption price (in US$ per share)	100
MECO | Series H Preferred Stock
Class of Stock [Line Items]
Voluntary liquidation price (in US$ per share)	100
Redemption price (in US$ per share)	$ 100