Consolidated Balance Sheets Parentheticals (Parentheticals) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 31	$ 30
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 10,160	$ 9,629
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	433,333,333	433,333,333
Common stock, shares issued	355,932,791	341,361,420
Common stock, shares outstanding	355,932,791	341,361,420