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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	$ 82,370	$ 79,406	$ 153,027	$ 155,222
Income taxes on regulated activities	(23,654)	(22,824)	(42,316)	(44,122)
Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	61,138	61,496	114,091	118,750
Income taxes on regulated activities	(18,325)	(18,626)	(32,719)	(36,034)
Hawaiian Electric Company, Inc. and Subsidiaries
Operating income	28,171	28,297	49,012	53,233
Hawaiian Electric Company, Inc. and Subsidiaries | Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	61,138	61,496	114,091	118,750
Income taxes on regulated activities	(18,333)	(18,574)	(32,428)	(35,939)
Revenues from nonregulated activities	(1,895)	(1,867)	(4,971)	(3,539)
Add: Expenses from nonregulated activities	955	452	1,719	816
Operating income	$ 41,865	$ 41,507	$ 78,411	$ 80,088