Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 14,297	$ 13,765
Common stock, par value	$ 0.30	$ 0.30
Common stock, shares authorized	1,800,000,000	1,800,000,000
Common stock, shares issued	963,347,000	992,020,000
Common stock held in treasury, shares	87,041,000	87,041,000