CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents		$ 84,476	$ 84,940
Accounts receivable, net		776,289	724,606
Accrued unbilled revenues		729,832	654,867
Inventories		604,226	608,584
Regulatory assets		363,655	344,630
Derivative instruments		38,224	33,842
Prepaid Taxes		106,697	163,023
Prepayments and other		138,682	155,734
Total current assets		2,842,081	2,770,226
Property, plant and equipment, net		32,841,750	31,205,851
Other assets
Nuclear decommissioning fund and other investments		2,091,858	1,902,995
Regulatory assets		3,080,867	2,858,741
Derivative instruments		50,189	51,083
Deposits and other		248,532	32,581
Total other assets		5,471,446	4,845,400
Total assets		41,155,277	38,821,477
Current liabilities
Current portion of long-term debt		255,529	657,021
Short-term debt		392,000	846,000
Accounts payable		1,044,959	960,982
Regulatory liabilities	[1]	220,894	306,830
Taxes accrued		457,392	438,189
Accrued interest		172,901	166,829
Dividends payable		172,456	162,410
Derivative instruments		26,959	29,839
Other		503,953	490,197
Total current liabilities		3,247,043	4,058,297
Deferred credits and other liabilities
Deferred income taxes		6,784,319	6,153,442
Deferred investment tax credits		63,216	68,419
Regulatory liabilities		1,383,212	1,332,889
Asset retirement obligations		2,782,229	2,608,562
Derivative instruments		148,146	168,311
Customer advances		195,214	228,999
Pension and employee benefit obligations		1,112,366	941,002
Other		223,965	261,756
Total deferred credits and other liabilities		12,692,667	11,763,380
Commitments and contingencies
Capitalization
Long-term debt		14,194,718	12,398,880
Common stock — 1,000,000,000 shares authorized of $2.50 par value; 507,222,795 and 507,535,523 shares outstanding at Dec. 31, 2016 and 2015, respectively		1,268,057	1,268,839
Additional paid in capital		5,881,494	5,889,106
Retained earnings		3,981,652	3,552,728
Accumulated other comprehensive loss		(110,354)	(109,753)
Total common stockholders’ equity		11,020,849	10,600,920
Total liabilities and equity		$ 41,155,277	$ 38,821,477

[1] (c) Revenue subject to refund of $46.0 million and $75.0 million for 2016 and 2015, respectively, is included in other current liabilities.