Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 192	$ 160
Accumulated depreciation	6,267	5,953
Accumulated amortization	$ 376	$ 327
Common stock, par value (USD per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	111,000,000	111,000,000
Common stock, shares outstanding (in shares)	75,000,000	77,000,000
Treasury stock (in shares)	36,000,000	33,000,000