CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 101,491	$ 84,940
Accounts receivable, net	729,386	724,606
Accrued unbilled revenues	525,423	654,867
Inventories	520,054	608,584
Regulatory assets	317,489	344,630
Derivative instruments	23,293	33,842
Deferred income taxes	180,513	140,219
Prepaid taxes	180,825	163,023
Prepayments and other	154,143	155,734
Total current assets	2,732,617	2,910,445
Property, plant and equipment, net	31,433,406	31,205,851
Other assets
Nuclear decommissioning fund and other investments	1,917,709	1,902,995
Regulatory assets	2,897,502	2,858,741
Derivative instruments	55,612	51,083
Other	32,998	32,581
Total other assets	4,903,821	4,845,400
Total assets	39,069,844	38,961,696
Current liabilities
Current portion of long-term debt	656,516	657,021
Short-term debt	183,000	846,000
Accounts payable	809,656	960,982
Regulatory liabilities	272,647	306,830
Taxes accrued	525,934	438,189
Accrued interest	148,112	166,829
Dividends payable	172,704	162,410
Derivative instruments	27,553	29,839
Other	392,446	490,197
Total current liabilities	3,188,568	4,058,297
Deferred credits and other liabilities
Deferred income taxes	6,493,644	6,293,661
Deferred investment tax credits	67,112	68,419
Regulatory liabilities	1,373,140	1,332,889
Asset retirement obligations	2,639,628	2,608,562
Derivative instruments	167,299	168,311
Customer advances	221,683	228,999
Pension and employee benefit obligations	812,998	941,002
Other	285,743	261,756
Total deferred credits and other liabilities	$ 12,061,247	$ 11,903,599
Commitments and contingencies
Capitalization
Long-term debt	$ 13,148,395	$ 12,398,880
Common stock — 1,000,000,000 shares authorized of $2.50 par value; 507,952,795 and 507,535,523 shares outstanding at March 31, 2016 and Dec. 31, 2015, respectively	1,269,882	1,268,839
Additional paid in capital	5,889,939	5,889,106
Retained earnings	3,620,421	3,552,728
Accumulated other comprehensive loss	(108,608)	(109,753)
Total common stockholders’ equity	10,671,634	10,600,920
Total liabilities and equity	$ 39,069,844	$ 38,961,696