Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 7	$ 7
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized (in shares)	100	100
Preferred Stock, Shares Issued (in shares)	0	0
Preferred Stock, Shares Outstanding (in shares)	0	0
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized (in shares)	1,500	1,500
Common Stock, Shares, Issued (in shares)	600	596
Common Stock, Shares, Outstanding (in shares)	586	595
Treasury Stock, Shares (in shares)	14	1