Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowances	$ 70	$ 86
Common stock, par value (in USD per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	849,890,566	860,861,998
Common stock, shares outstanding (in shares)	848,380,679	859,406,651
Treasury stock, at cost (in shares)	1,509,887	1,455,347