Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed assets, accumulated depreciation and amortization	$ 1,729	$ 1,683
Preferred stock, par value (usd per share)	$ 1	$ 1
Preferred stock, shares authorized	6,000,000	6,000,000
Preferred stock, shares issued	0	0
Common stock, par value (usd per share)	$ 1	$ 1
Common stock, shares authorized	1,600,000,000	1,600,000,000
Common stock, shares issued	560,641,640	560,641,640
Treasury shares, shares	45,617,551	46,150,415