Reconciliation of electric utility operating income per HEI and HECO consolidated statements of income (Details) - HECO (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	$ 63,661	$ 63,631	$ 127,036	$ 124,338
Income taxes on regulated activities	(13,742)	(16,013)	(29,806)	(31,292)
Hawaiian Electric Company, Inc. and Subsidiaries
Income taxes on regulated activities	(11,160)	(11,113)	(22,770)	(22,154)
Operating income	30,540	30,850	63,259	61,257
Hawaiian Electric Company, Inc. and Subsidiaries | Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	42,518	41,435	87,726	84,044
Income taxes on regulated activities	(11,160)	(11,113)	(22,770)	(22,154)
Revenues from nonregulated activities	(1,086)	(2,001)	(2,120)	(3,400)
Add: Expenses from nonregulated activities	268	2,529	423	2,767
Operating income	30,540	30,850	63,259	61,257
Electric utility
Operating income from regulated and nonregulated activities before income taxes (per HEI consolidated statements of income)	42,518	41,435	87,726	84,044
Income taxes on regulated activities	$ (11,080)	$ (10,213)	$ (22,659)	$ (21,174)