Consolidated Statements Of Financial Position (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Trade accounts receivable, allowances	$ 92	$ 78
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized	15,000,000	15,000,000
Preferred stock, issued	0	0
Class A common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Class A common stock, shares authorized	1,000,000,000	1,000,000,000
Class A common stock, shares issued	569,000,000	577,000,000
Class A common stock, shares outstanding	569,000,000	577,000,000