Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Receivables, allowance for doubtful accounts	$ 73	$ 79
Preferred stock, par (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par (in dollars per share)	$ 0.1667	$ 0.1667
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	198,628,992	198,594,841
Treasury stock, shares (in shares)	66,202,947	63,028,169