Bank segment (HEI only) Additional Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Hawaiian Electric Industries, Inc. | Consolidated subsidiary | American Savings Bank (ASB) | Management and administrative services
Revenue from related party	$ 2,300,000	$ 2,300,000	$ 1,900,000
Hawaiian Electric Industries, Inc. | Maximum
Obligation to contribute additional capital under the Capital Maintenance Agreement	65,100,000
Reduction in obligation to contribute additional capital under the Capital Maintenance Agreement	28,300,000
American Savings Bank (ASB)
Borrowing capacity	1,200,000,000	1,100,000,000
Cash dividends paid	$ 36,000,000	$ 40,000,000