CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 132,313	$ 107,144
Accounts receivable, net	885,098	744,160
Accrued unbilled revenues	575,813	687,230
Inventories	436,237	576,538
Regulatory assets	481,473	417,801
Derivative instruments	70,275	91,707
Deferred income taxes	252,658	341,202
Prepayments and other	295,479	252,258
Total current assets	3,129,346	3,218,040
Property, plant and equipment, net	26,541,482	26,122,159
Other assets
Nuclear decommissioning fund and other investments	1,793,067	1,755,990
Regulatory assets	2,497,280	2,509,218
Derivative instruments	67,513	84,842
Other	170,064	217,241
Total other assets	4,527,924	4,567,291
Total assets	34,198,752	33,907,490
Current liabilities
Current portion of long-term debt	282,133	280,763
Short-term debt	765,000	759,000
Accounts payable	1,061,874	1,261,238
Regulatory liabilities	258,946	274,769
Taxes accrued	461,520	378,766
Accrued interest	132,589	159,372
Dividends payable	150,250	139,432
Derivative instruments	22,358	23,382
Other	333,078	377,776
Total current liabilities	3,467,748	3,654,498
Deferred credits and other liabilities
Deferred income taxes	5,412,381	5,331,046
Deferred investment tax credits	77,796	79,239
Regulatory liabilities	1,090,733	1,059,395
Asset retirement obligations	1,838,521	1,815,390
Derivative instruments	199,578	209,224
Customer advances	272,583	275,555
Pension and employee benefit obligations	642,126	769,222
Other	244,543	237,217
Total deferred credits and other liabilities	9,778,261	9,776,288
Commitments and contingencies
Capitalization
Long-term debt	11,205,319	10,910,754
Common stock — 1,000,000,000 shares authorized of $2.50 par value; 501,151,619 and 497,971,508 shares outstanding at March 31, 2014 and Dec. 31, 2013, respectively	1,252,879	1,244,929
Additional paid in capital	5,681,150	5,619,313
Retained earnings	2,918,215	2,807,983
Accumulated other comprehensive loss	(104,820)	(106,275)
Total common stockholders’ equity	9,747,424	9,565,950
Total liabilities and equity	$ 34,198,752	$ 33,907,490