Condensed Balance Sheet (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and Cash Equivalents, at Carrying Value	$ 3,063	$ 3,805
Receivables - customers, net	23,309	23,867
Receivables - affiliates	4,896	5,027
Other receivables, net	628	673
Money pool notes receivable, net	35,063	31,645
Materials, supplies and fuel	21,284	20,633
Deferred income tax assets, net, current	1,563	16,631
Regulatory assets, current	4,891	4,998
Other, current assets	5,432	5,781
Total current assets	100,129	113,060
Investments	4,438	4,359
Property, plant and equipment	1,036,672	1,024,768
Less accumulated depreciation and amortization	(326,160)	(322,830)
Total property, plant and equipment, net	710,512	701,938
Other assets:
Regulatory assets, non-current	48,921	48,244
Other, non-current assets	5,685	5,322
Total other assets	54,606	53,566
TOTAL ASSETS	869,685	872,923
Current liabilities:
Accounts payable	17,128	14,318
Accounts payable - affiliates	18,030	21,896
Accrued liabilities	17,232	15,477
Regulatory liabilities, current	22	37
Total current liabilities	52,412	51,728
Long-term debt, net of current maturities	269,945	269,944
Liabilities, Noncurrent
Deferred income tax liability, net, non-current	146,521	158,918
Regulatory liabilities, non-current	45,845	43,849
Benefit plan liabilities	26,627	25,888
Other, non-current liabilities	3,274	3,138
Total deferred credits and other liabilities	222,267	231,793
Stockholder’s equity:
Common stock $1 par value; 50,000,000 shares authorized; 23,416,396 shares issued	23,416	23,416
Additional paid-in capital	39,575	39,575
Retained earnings	263,469	257,887
Accumulated other comprehensive loss	(1,399)	(1,420)
Total stockholder’s equity	325,061	319,458
TOTAL LIABILITIES AND STOCKHOLDER’S EQUITY	$ 869,685	$ 872,923