CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) [Abstract]
Operating Revenues	$ 65,187	$ 61,344	$ 245,510	$ 258,060
Operating Expenses:
Cost of Sales (Excluding depreciation)	28,259	23,941	116,833	140,816
Operations	17,403	16,485	35,676	34,292
Maintenance	3,215	2,785	6,224	5,601
Depreciation	7,523	7,319	14,983	14,398
Energy and Other Taxes	1,722	1,590	6,236	5,938
Total Operating Expenses	58,122	52,120	179,952	201,045
Operating Income	7,065	9,224	65,558	57,015
Other Income and Expense	515	240	1,393	473
Interest Charges	(4,895)	(4,163)	(9,924)	(8,178)
Income Before Income Taxes	2,685	5,301	57,027	49,310
Income Taxes	(1,065)	(2,125)	(23,111)	(20,264)
Net Income	$ 1,620	$ 3,176	$ 33,916	$ 29,046