Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for Doubtful Accounts	$ 8	$ 7
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,500,000,000	1,500,000,000
Common stock, shares, issued (in shares)	607,000,000	604,000,000
Common stock, shares, outstanding (in shares)	554,000,000	569,000,000
Treasury stock, shares (in shares)	53,000,000	35,000,000