CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 1,571	$ 6,445
Accounts receivable, net	51,838	51,667
Accrued unbilled revenues	48,668	51,579
Inventories	25,703	26,616
Regulatory assets	14,133	14,084
Prepaid taxes	21,841	21,097
Prepayments and other	2,991	2,555
Total current assets	166,745	174,043
Property, plant and equipment, net	1,207,698	1,130,342
Other assets
Regulatory assets	229,910	214,402
Other investments	4,148	4,036
Other	2,970	3,705
Total other assets	237,028	222,143
Total assets	1,611,471	1,526,528
Current liabilities
Current portion of long-term debt	1,286	1,502
Short-term debt	66,000	0
Notes payable to affiliates	500	37,550
Accounts payable	30,897	35,124
Accounts payable to affiliates	23,285	36,320
Dividends payable to parent	8,107	8,441
Regulatory liabilities	16,609	10,377
Environmental liabilities	30,699	5,074
Accrued interest	6,521	6,438
Taxes accrued	1,238	867
Derivative instruments	2,514	1,787
Other	10,155	12,469
Total current liabilities	197,811	155,949
Deferred credits and other liabilities
Deferred income taxes	234,222	198,793
Deferred investment tax credits	8,499	9,110
Regulatory liabilities	119,187	117,318
Environmental liabilities	79,399	97,740
Pension and employee benefit obligations	60,328	51,592
Customer advances	15,765	17,352
Other	7,024	8,142
Total deferred credits and other liabilities	524,424	500,047
Commitments and contingencies
Capitalization
Long-term debt	368,083	367,854
Common stock - 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at Dec. 31, 2011 and 2010, respectively	93,300	93,300
Additional paid in capital	187,071	187,071
Retained earnings	241,296	222,897
Accumulated other comprehensive loss	(514)	(590)
Total common stockholder's equity	521,153	502,678
Total liabilities and equity	$ 1,611,471	$ 1,526,528