CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 63,530	$ 60,684
Restricted cash	328	95,287
Accounts receivable, net	645,264	753,120
Accrued unbilled revenues	549,728	688,740
Inventories	473,137	618,232
Regulatory assets	366,226	402,235
Derivative instruments	88,368	64,340
Deferred income taxes	178,470	178,446
Prepayments and other	195,357	121,480
Total current assets	2,560,408	2,982,564
Property, plant and equipment, net	23,047,854	22,353,367
Other assets
Nuclear decommissioning fund and other investments	1,522,203	1,463,515
Regulatory assets	2,359,097	2,389,008
Derivative instruments	137,015	152,887
Other	193,566	155,926
Total other assets	4,211,881	4,161,336
Total assets	29,820,143	29,497,267
Current liabilities
Current portion of long-term debt	1,311,594	1,059,922
Short-term debt	481,000	219,000
Accounts payable	871,069	902,078
Regulatory liabilities	193,509	275,095
Taxes accrued	215,159	289,713
Accrued interest	176,855	177,111
Dividends payable	131,565	126,487
Derivative instruments	111,836	157,414
Other	338,635	381,819
Total current liabilities	3,831,222	3,588,639
Deferred credits and other liabilities
Deferred income taxes	4,320,320	4,020,377
Deferred investment tax credits	84,895	86,743
Regulatory liabilities	1,066,486	1,101,534
Asset retirement obligations	1,695,560	1,651,793
Derivative instruments	253,364	263,906
Customer advances	244,922	248,345
Pension and employee benefit obligations	826,413	1,001,906
Other	217,053	203,313
Total deferred credits and other liabilities	8,709,013	8,577,917
Commitments and contingencies
Capitalization
Long-term debt	8,706,403	8,848,513
Common stock - 1,000,000,000 shares authorized of $2.50 par value; 487,285,506 and 486,493,933 shares outstanding at June 30, 2012 and Dec. 31, 2011, respectively	1,218,214	1,216,234
Additional paid in capital	5,316,658	5,327,443
Retained earnings	2,140,639	2,032,556
Accumulated other comprehensive loss	(102,006)	(94,035)
Total common stockholders' equity	8,573,505	8,482,198
Total liabilities and equity	$ 29,820,143	$ 29,497,267