Consolidation and Nature of Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating Revenues
OPERATING REVENUES	$ 620,631	$ 648,847
Operating Expenses
Operations and maintenance	210,663	255,029
Depreciation and amortization	100,109	106,583
Other expenses	3,068	1,820
Other
Other expense (Note 11)	(4,068)	(1,741)
Income Taxes	(4,645)	(6,005)
Income From Continuing Operations	284	(10,368)
Income From Discontinued Operations	(765)	694
Cash Flows from Operating Activities
Change in other long-term assets	(21,469)	(33,169)
Change in other long-term liabilities	22,362	35,418
As previously reported
Operating Revenues
Regulated electricity segment revenues		647,974
Other revenues		11,601
Operating Expenses
Operations and maintenance		256,486
Depreciation and amortization		106,601
Other expenses		9,716
Other
Other expense (Note 11)		(1,699)
Income Taxes		(5,649)
Income From Continuing Operations		(9,325)
Income From Discontinued Operations		(349)
Cash Flows from Operating Activities
Expenditures for real estate investments		(40)
Gains and other changes in real estate assets		(3)
Change in other long-term assets		(33,129)
Change in other long-term liabilities		35,421
Reclassifications for discontinued operations
Operating Revenues
Regulated electricity segment revenues		(647,974)
Other revenues		(11,601)
OPERATING REVENUES		648,847
Operating Expenses
Operations and maintenance		(1,457)
Depreciation and amortization		(18)
Other expenses		(7,896)
Other
Other expense (Note 11)		(42)
Income Taxes		(356)
Income From Continuing Operations		(1,043)
Income From Discontinued Operations		1,043
Cash Flows from Operating Activities
Expenditures for real estate investments		40
Gains and other changes in real estate assets		3
Change in other long-term assets		(40)
Change in other long-term liabilities		(3)
Amount reported after reclassification for discontinued operations
Operating Revenues
OPERATING REVENUES		648,847
Operating Expenses
Operations and maintenance		255,029
Depreciation and amortization		106,583
Other expenses		1,820
Other
Other expense (Note 11)		(1,741)
Income Taxes		(6,005)
Income From Continuing Operations		(10,368)
Income From Discontinued Operations		694
Cash Flows from Operating Activities
Change in other long-term assets		(33,169)
Change in other long-term liabilities		$ 35,418