CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 60,684	$ 108,437
Restricted cash	95,287	0
Accounts receivable, net	753,120	718,474
Accrued unbilled revenues	688,740	708,691
Inventories	618,232	560,800
Regulatory assets	402,235	388,541
Derivative instruments	64,340	54,079
Deferred income taxes	178,446	0
Prepayments and other	121,480	193,621
Total current assets	2,982,564	2,732,643
Property, plant and equipment, net	22,353,367	20,663,082
Other assets
Nuclear decommissioning fund and other investments	1,463,515	1,476,435
Regulatory assets	2,389,008	2,151,460
Derivative instruments	152,887	184,026
Other	155,926	180,044
Total other assets	4,161,336	3,991,965
Total assets	29,497,267	27,387,690
Current liabilities
Current portion of long-term debt	1,059,922	55,415
Short-term debt	219,000	466,400
Accounts payable	902,078	979,750
Regulatory liabilities	275,095	156,038
Taxes accrued	289,713	254,320
Accrued interest	177,111	163,907
Dividends payable	126,487	122,847
Derivative instruments	157,414	61,745
Other	381,819	276,111
Total current liabilities	3,588,639	2,536,533
Deferred credits and other liabilities
Deferred income taxes	4,020,377	3,390,027
Deferred investment tax credits	86,743	92,937
Regulatory liabilities	1,101,534	1,179,765
Asset retirement obligations	1,651,793	969,310
Derivative instruments	263,906	285,986
Customer advances	248,345	269,087
Pension and employee benefit obligations	1,001,906	962,767
Other	203,313	249,635
Total deferred credits and other liabilities	8,577,917	7,399,514
Commitments and contingencies
Capitalization
Long-term debt	8,848,513	9,263,144
Preferred stock - 7,000,000 shares authorized of $100 par value; no shares and 1,049,800 shares outstanding at Dec. 31, 2011 and Dec. 31, 2010, respectively	0	104,980
Common stock - 1,000,000,000 shares authorized of $2.50 par value; 486,493,933 and 482,333,750 shares outstanding at Dec. 31, 2011 and Dec. 31, 2010, respectively	1,216,234	1,205,834
Additional paid in capital	5,327,443	5,229,075
Retained earnings	2,032,556	1,701,703
Accumulated other comprehensive loss	(94,035)	(53,093)
Total common stockholders' equity	8,482,198	8,083,519
Total liabilities and equity	$ 29,497,267	$ 27,387,690