Reconciliation of electric utility operating income per HEI and HECO consolidated statements of income (Details) - HECO (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	$ 90,099	$ 91,702	$ 243,126	$ 246,924
Income taxes on regulated activities	(22,841)	(25,804)	(65,157)	(69,926)
Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	71,914	74,819	186,005	193,569
Income taxes on regulated activities	(19,058)	(22,395)	(51,777)	(58,429)
Hawaiian Electric Company, Inc. and Subsidiaries
Operating income	36,200	35,300	85,212	88,533
Hawaiian Electric Company, Inc. and Subsidiaries | Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	71,914	74,819	186,005	193,569
Income taxes on regulated activities	(18,928)	(22,352)	(51,356)	(58,291)
Revenues from nonregulated activities	(2,182)	(1,892)	(7,153)	(5,431)
Add: Expenses from nonregulated activities	1,082	804	2,801	1,620
Operating income	$ 51,886	$ 51,379	$ 130,297	$ 131,467