CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) shares in Millions, $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Accounts receivable, allowances for doubtful accounts	$ 63	$ 68
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.000006	$ 0.000006
Class A Common Stock
Stockholders' equity:
Common stock, shares authorized	5,000	5,000
Common stock, shares issued	2,311	2,293
Common stock, shares outstanding	2,311	2,293
Common stock, outstanding shares subject to repurchase	7	8
Class B Common Stock
Stockholders' equity:
Common stock, shares authorized	4,141	4,141
Common stock, shares issued	549	552
Common stock, shares outstanding	549	552
Common stock, outstanding shares subject to repurchase	3	3