CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 1,526		$ 4,459
Accounts receivable, net	48,119	[1]	50,706	[1]
Accrued unbilled revenues	38,062		49,138
Inventories	22,999		19,685
Regulatory assets	17,011		12,048
Prepaid taxes	16,063		24,688
Deferred income taxes	10,466		0
Prepayments and other	2,889		4,394
Total current assets	157,135		165,118
Property, plant and equipment, net	1,378,647		1,298,236
Other assets
Regulatory assets	237,339		240,459
Other investments	3,483		3,232
Other	3,677		4,040
Total other assets	244,499		247,731
Total assets	1,780,281		1,711,085
Current liabilities
Current portion of long-term debt	103		1,246
Short-term debt	11,000		39,000
Notes payable to affiliates	470		550
Accounts payable	29,096		30,723
Accounts payable to affiliates	29,158		31,556
Dividends payable to parent	8,038		7,667
Regulatory liabilities	4,233		6,086
Taxes accrued	8,303		839
Environmental liabilities	23,817		23,427
Accrued interest	7,549		7,304
Other	9,627		10,955
Total current liabilities	131,394		159,353
Deferred credits and other liabilities
Deferred income taxes	294,026		261,800
Deferred investment tax credits	9,576		8,911
Regulatory liabilities	125,982		123,746
Environmental liabilities	81,862		84,655
Customer advances	16,861		15,631
Pension and employee benefit obligations	54,354		63,643
Other	9,141		8,923
Total deferred credits and other liabilities	591,802		567,309
Commitments and contingencies
Capitalization
Long-term debt	468,511		467,317
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at Sept. 30, 2013 and Dec. 31, 2012, respectively	93,300		93,300
Additional paid in capital	232,349		189,867
Retained earnings	263,305		234,376
Accumulated other comprehensive loss	(380)		(437)
Total common stockholder’s equity	588,574		517,106
Total liabilities and equity	$ 1,780,281		$ 1,711,085

[1] Accounts receivable, net includes $14 and $586 due from affiliates as of Sept. 30, 2013 and Dec. 31, 2012, respectively.