Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 14,621	$ 14,346
Common stock, par value	$ 0.30	$ 0.30
Common stock, shares authorized	1,800,000,000	1,800,000,000
Common stock, shares issued	960,450,000	958,388,000
Common stock held in treasury, shares	87,041,000	87,041,000