CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Accounts receivable, allowances for doubtful accounts	$ 94	$ 68
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.000006	$ 0.000006
Class A Common Stock
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.000006
Common stock, shares authorized	5,000,000,000	5,000,000,000
Common stock, shares, issued	2,354,000,000	2,293,000,000
Common stock, shares, outstanding	2,354,000,000	2,293,000,000
Common stock, outstanding shares subject to repurchase	4,000,000	8,000,000
Class B Common Stock
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.000006
Common stock, shares authorized	4,141,000,000	4,141,000,000
Common stock, shares, issued	538,000,000	552,000,000
Common stock, shares, outstanding	538,000,000	552,000,000
Common stock, outstanding shares subject to repurchase	2,000,000	3,000,000