CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 18,721	$ 5,150
Accounts receivable, net	315,019	277,461
Accounts receivable from affiliates	14,938	93,544
Investments in utility money pool arrangement	200,000	0
Accrued unbilled revenues	236,045	285,624
Inventories	181,360	223,794
Regulatory assets	146,980	143,689
Deferred income taxes	25,194	0
Derivative instruments	4,237	4,889
Prepayments and other	33,632	22,970
Total current assets	1,176,126	1,057,121
Property, plant and equipment, net	10,152,771	10,030,991
Other assets
Regulatory assets	916,822	934,728
Derivative instruments	8,908	10,868
Other	50,114	50,461
Total other assets	975,844	996,057
Total assets	12,304,741	12,084,169
Current liabilities
Current portion of long-term debt	6,477	256,297
Short-term debt	0	154,000
Accounts payable	332,212	359,969
Accounts payable to affiliates	26,556	30,001
Regulatory liabilities	68,331	33,723
Taxes accrued	186,670	153,614
Accrued interest	31,196	48,014
Dividends payable to parent	66,678	66,803
Derivative instruments	7,832	8,753
Other	65,952	72,669
Total current liabilities	791,904	1,183,843
Deferred credits and other liabilities
Deferred income taxes	1,878,873	1,782,828
Deferred investment tax credits	41,375	42,097
Regulatory liabilities	431,799	417,404
Asset retirement obligations	44,308	43,751
Derivative instruments	27,953	30,605
Customer advances	236,126	229,498
Pension and employee benefit obligations	280,314	324,625
Other	66,373	69,307
Total deferred credits and other liabilities	3,007,121	2,940,115
Commitments and contingencies
Capitalization
Long-term debt	3,870,164	3,374,476
Common stock - 100 shares authorized at $0.01 par value; 100 shares outstanding at March 31, 2013 and Dec. 31, 2012	0	0
Additional paid in capital	3,415,669	3,415,669
Retained earnings	1,242,865	1,192,937
Accumulated other comprehensive loss	(22,982)	(22,871)
Total common stockholder's equity	4,635,552	4,585,735
Total liabilities and equity	$ 12,304,741	$ 12,084,169