CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 633,919	$ 3,763
Accounts receivable, net	265,144	317,039
Accounts receivable from affiliates	13,346	12,063
Investments in utility money pool arrangement	120,000	52,000
Accrued unbilled revenues	193,664	304,544
Inventories	242,444	253,997
Regulatory assets	156,906	196,311
Deferred income taxes	41,443	33,349
Derivative instruments	6,403	4,930
Prepayments and other	53,471	19,504
Total current assets	1,726,740	1,197,500
Property, plant and equipment, net	9,844,906	9,475,571
Other assets
Regulatory assets	793,037	809,011
Derivative instruments	11,957	15,357
Other	49,561	36,066
Total other assets	854,555	860,434
Total assets	12,426,201	11,533,505
Current liabilities
Current portion of long-term debt	856,122	605,633
Accounts payable	321,702	362,580
Accounts payable to affiliates	26,352	48,371
Regulatory liabilities	26,378	68,809
Taxes accrued	100,348	116,376
Accrued interest	56,066	53,749
Dividends payable to parent	66,470	66,926
Derivative instruments	8,408	85,518
Other	75,782	75,671
Total current liabilities	1,537,628	1,483,633
Deferred credits and other liabilities
Deferred income taxes	1,963,501	1,775,448
Deferred investment tax credits	42,770	44,725
Regulatory liabilities	414,801	444,442
Asset retirement obligations	44,001	42,207
Derivative instruments	32,443	38,325
Customer advances	230,029	226,097
Pension and employee benefit obligations	163,396	222,707
Other	68,444	69,561
Total deferred credits and other liabilities	2,959,385	2,863,512
Commitments and contingencies
Capitalization
Long-term debt	3,424,623	2,880,642
Common stock - 100 shares authorized at $0.01 par value; 100 shares outstanding at Sept. 30, 2012 and Dec. 31, 2011	0	0
Additional paid in capital	3,344,508	3,316,386
Retained earnings	1,182,800	1,001,709
Accumulated other comprehensive loss	(22,743)	(12,377)
Total common stockholder's equity	4,504,565	4,305,718
Total liabilities and equity	$ 12,426,201	$ 11,533,505