Consolidation and Nature of Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating Revenues
OPERATING REVENUES	$ 878,576	$ 799,799	$ 1,499,207	$ 1,448,646
Cash Flows from Operating Activities
Change in other long-term assets			(1,692)	(26,225)
As previously reported
Operating Revenues
Regulated electricity segment		798,669		1,446,643
Other revenues		1,130		2,003
Cash Flows from Operating Activities
Expenditures for real estate investments				(40)
Change in other long-term assets				(26,185)
Reclassifications to conform to current year presentation
Operating Revenues
Regulated electricity segment		(798,669)		(1,446,643)
Other revenues		(1,130)		(2,003)
OPERATING REVENUES		799,799		1,448,646
Cash Flows from Operating Activities
Expenditures for real estate investments				40
Change in other long-term assets				(40)
Amount reported after reclassification to conform to current year presentation
Operating Revenues
OPERATING REVENUES		799,799		1,448,646
Cash Flows from Operating Activities
Change in other long-term assets				$ (26,225)