CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 137,868	$ 107,144
Accounts receivable, net	760,213	744,160
Accrued unbilled revenues	574,824	687,230
Inventories	634,262	576,538
Regulatory assets	415,197	417,801
Derivative instruments	120,654	91,707
Deferred income taxes	283,047	341,202
Prepayments and other	270,529	252,258
Total current assets	3,196,594	3,218,040
Property, plant and equipment, net	27,630,363	26,122,159
Other assets
Nuclear decommissioning fund and other investments	1,816,962	1,755,990
Regulatory assets	2,488,580	2,509,218
Derivative instruments	53,577	84,842
Other	177,365	217,241
Total other assets	4,536,484	4,567,291
Total assets	35,363,441	33,907,490
Current liabilities
Current portion of long-term debt	257,506	280,763
Short-term debt	697,000	759,000
Accounts payable	1,061,385	1,261,238
Regulatory liabilities	379,824	274,769
Taxes accrued	371,959	378,766
Accrued interest	132,084	159,372
Dividends payable	151,623	139,432
Derivative instruments	22,924	23,382
Other	396,564	377,776
Total current liabilities	3,470,869	3,654,498
Deferred credits and other liabilities
Deferred income taxes	5,750,946	5,331,046
Deferred investment tax credits	74,910	79,239
Regulatory liabilities	1,140,619	1,059,395
Asset retirement obligations	1,922,022	1,815,390
Derivative instruments	187,445	209,224
Customer advances	262,734	275,555
Pension and employee benefit obligations	653,599	769,222
Other	243,917	237,217
Total deferred credits and other liabilities	10,236,192	9,776,288
Commitments and contingencies
Capitalization
Long-term debt	11,501,720	10,910,754
Common stock — 1,000,000,000 shares authorized of $2.50 par value; 505,424,067 and 497,971,508 shares outstanding at Sept. 30, 2014 and Dec. 31, 2013, respectively	1,263,560	1,244,929
Additional paid in capital	5,815,714	5,619,313
Retained earnings	3,177,387	2,807,983
Accumulated other comprehensive loss	(102,001)	(106,275)
Total common stockholders’ equity	10,154,660	9,565,950
Total liabilities and equity	$ 35,363,441	$ 33,907,490