CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 99,540	$ 107,144
Accounts receivable, net	742,730	744,160
Accrued unbilled revenues	609,673	687,230
Inventories	501,270	576,538
Regulatory assets	462,185	417,801
Derivative instruments	154,940	91,707
Deferred income taxes	282,765	341,202
Prepayments and other	270,717	252,258
Total current assets	3,123,820	3,218,040
Property, plant and equipment, net	27,070,377	26,122,159
Other assets
Nuclear decommissioning fund and other investments	1,838,648	1,755,990
Regulatory assets	2,451,558	2,509,218
Derivative instruments	59,732	84,842
Other	173,509	217,241
Total other assets	4,523,447	4,567,291
Total assets	34,717,644	33,907,490
Current liabilities
Current portion of long-term debt	7,522	280,763
Short-term debt	777,800	759,000
Accounts payable	967,251	1,261,238
Regulatory liabilities	366,579	274,769
Taxes accrued	269,020	378,766
Accrued interest	158,663	159,372
Dividends payable	151,097	139,432
Derivative instruments	20,874	23,382
Other	341,123	377,776
Total current liabilities	3,059,929	3,654,498
Deferred credits and other liabilities
Deferred income taxes	5,551,537	5,331,046
Deferred investment tax credits	76,353	79,239
Regulatory liabilities	1,107,253	1,059,395
Asset retirement obligations	1,897,942	1,815,390
Derivative instruments	194,553	209,224
Customer advances	268,690	275,555
Pension and employee benefit obligations	650,596	769,222
Other	237,241	237,217
Total deferred credits and other liabilities	9,984,165	9,776,288
Commitments and contingencies
Capitalization
Long-term debt	11,752,778	10,910,754
Common stock — 1,000,000,000 shares authorized of $2.50 par value; 505,105,562 and 497,971,508 shares outstanding at June 30, 2014 and Dec. 31, 2013, respectively	1,262,764	1,244,929
Additional paid in capital	5,799,968	5,619,313
Retained earnings	2,961,406	2,807,983
Accumulated other comprehensive loss	(103,366)	(106,275)
Total common stockholders’ equity	9,920,772	9,565,950
Total liabilities and equity	$ 34,717,644	$ 33,907,490