Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 161	$ 185
Accumulated depreciation	6,542	6,055
Accumulated amortization	$ 429	$ 387
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)	73,000,000	74,000,000
Treasury stock (in shares)	38,000,000	37,000,000