Earnings per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Numerator
Net income	$ 642	$ 219
Less: Net income attributable to participating securities	3	2
Net income attributable to common stockholders	639	217
Denominator
Number of shares used for basic EPS computation (in shares)	2,545	2,386
Basic EPS (in dollars per share)	$ 0.25	$ 0.09
Numerator
Net income attributable to common stockholders	639	217
Denominator
Number of shares used for basic EPS computation (in shares)	2,545	2,386
Number of shares used for diluted EPS computation (in shares)	2,609	2,499
Diluted EPS (in dollars per share)	$ 0.25	$ 0.09
Class A Common Stock
Numerator
Net income	498	156
Less: Net income attributable to participating securities	2	1
Net income attributable to common stockholders	496	155
Denominator
Weighted average shares outstanding (in shares)	1,982	1,709
Less: Shares subject to repurchase (in shares)	5	4
Number of shares used for basic EPS computation (in shares)	1,977	1,705
Basic EPS (in dollars per share)	$ 0.25	$ 0.09
Numerator
Net income attributable to common stockholders	496	155
Reallocation of net income attributable to participating securities	3	2
Reallocation of net income as a result of conversion of Class B to Class A common stock	143	62
Reallocation of net income to Class B common stock	0	0
Net income attributable to common stockholders for diluted EPS	642	219
Denominator
Number of shares used for basic EPS computation (in shares)	1,977	1,705
Conversion of Class B to Class A common stock (in shares)	568	681
Shares subject to repurchase (in shares)	8	4
Number of shares used for diluted EPS computation (in shares)	2,609	2,499
Diluted EPS (in dollars per share)	$ 0.25	$ 0.09
Class A Common Stock | Employee Stock Options
Denominator
Share based payment arrangements (in shares)	15	80
Class A Common Stock | Restricted Stock Units (RSUs)
Denominator
Share based payment arrangements (in shares)	41	29
Class B Common Stock
Numerator
Net income	144	63
Less: Net income attributable to participating securities	1	1
Net income attributable to common stockholders	143	62
Denominator
Weighted average shares outstanding (in shares)	574	691
Less: Shares subject to repurchase (in shares)	6	10
Number of shares used for basic EPS computation (in shares)	568	681
Basic EPS (in dollars per share)	$ 0.25	$ 0.09
Numerator
Net income attributable to common stockholders	143	62
Reallocation of net income attributable to participating securities	0	0
Reallocation of net income as a result of conversion of Class B to Class A common stock	0	0
Reallocation of net income to Class B common stock	7	7
Net income attributable to common stockholders for diluted EPS	$ 150	$ 69
Denominator
Number of shares used for basic EPS computation (in shares)	568	681
Conversion of Class B to Class A common stock (in shares)	0	0
Shares subject to repurchase (in shares)	5	4
Number of shares used for diluted EPS computation (in shares)	608	794
Diluted EPS (in dollars per share)	$ 0.25	$ 0.09
Class B Common Stock | Employee Stock Options
Denominator
Share based payment arrangements (in shares)	15	80
Class B Common Stock | Restricted Stock Units (RSUs)
Denominator
Share based payment arrangements (in shares)	20	29
Restricted Stock Units (RSUs)
Earnings Per Share, Basic, by Common Class, Including Two Class Method
Antidilutive securities excluded from computation of earnings per share	3	18