Consolidated Balance Sheets (Parenthetical) $ in Millions	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares
Statement Of Financial Position [Abstract]
Trade and other receivables, allowances for doubtful accounts and sales returns | $	$ 26	$ 29
Common stock, shares authorized	1,185,800,000	1,185,800,000
Common stock, shares issued	362,338,369	382,622,922
Common stock, shares outstanding	362,338,369	372,757,598