Regulation (Revised Fixed Fuel Factor) (Details)	Dec. 31, 2011	Nov. 23, 2010 PUCT Docket No. 38895	Jul. 15, 2011 PUCT Docket Number 39599
Regulation [Line Items]
Increase (Decrease) in Fuel Factor (in percent)	11.00%	(14.70%)	9.40%