CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 15,446	$ 5,150
Accounts receivable, net	282,823	277,461
Accounts receivable from affiliates	26,235	93,544
Investments in utility money pool arrangement	135,000	0
Accrued unbilled revenues	205,277	285,624
Inventories	251,234	223,794
Regulatory assets	142,973	143,689
Deferred income taxes	63,784	0
Derivative instruments	8,181	4,889
Prepayments and other	18,504	22,970
Total current assets	1,149,457	1,057,121
Property, plant and equipment, net	10,501,875	10,030,991
Other assets
Regulatory assets	904,546	934,728
Derivative instruments	7,333	10,868
Other	50,000	50,461
Total other assets	961,879	996,057
Total assets	12,613,211	12,084,169
Current liabilities
Current portion of long-term debt	281,906	256,297
Short-term debt	0	154,000
Accounts payable	332,775	359,969
Accounts payable to affiliates	34,800	30,001
Regulatory liabilities	47,204	33,723
Taxes accrued	158,996	153,614
Accrued interest	31,838	48,014
Dividends payable to parent	65,000	66,803
Derivative instruments	8,084	8,753
Other	68,528	72,669
Total current liabilities	1,029,131	1,183,843
Deferred credits and other liabilities
Deferred income taxes	2,091,827	1,782,828
Deferred investment tax credits	39,926	42,097
Regulatory liabilities	428,344	417,404
Asset retirement obligations	44,505	43,751
Derivative instruments	24,663	30,605
Customer advances	241,705	229,498
Pension and employee benefit obligations	280,486	324,625
Other	67,614	69,307
Total deferred credits and other liabilities	3,219,070	2,940,115
Commitments and contingencies
Capitalization
Long-term debt	3,592,116	3,374,476
Common stock — 100 shares authorized at $0.01 par value; 100 shares outstanding at Sept. 30, 2013 and Dec. 31, 2012	0	0
Additional paid in capital	3,420,154	3,415,669
Retained earnings	1,375,968	1,192,937
Accumulated other comprehensive loss	(23,228)	(22,871)
Total common stockholder’s equity	4,772,894	4,585,735
Total liabilities and equity	$ 12,613,211	$ 12,084,169