Earnings per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Numerator
Net income	$ 53	$ 1,000	$ 606
Less: Net income attributable to participating securities	21	332	234
Net income attributable to Class A and Class B common stockholders	32	668	372
Denominator
Number of shares used for basic EPS computation	2,006	1,294	1,107
Basic EPS	$ 0.02	$ 0.52	$ 0.34
Numerator
Net income attributable to Class A and Class B common stockholders	32	668	372
Denominator
Number of shares used for basic EPS computation	2,006	1,294	1,107
Number of shares used for diluted EPS computation	2,166	1,508	1,414
Diluted EPS	$ 0.01	$ 0.46	$ 0.28
Class A Common Stock
Numerator
Net income	18	85	18
Less: Net income attributable to participating securities	7	28	7
Net income attributable to Class A and Class B common stockholders	11	57	11
Denominator
Weighted average shares outstanding	668	110	32
Less: Shares subject to repurchase	1	0	0
Number of shares used for basic EPS computation	667	110	32
Basic EPS	$ 0.02	$ 0.52	$ 0.34
Numerator
Net income attributable to Class A and Class B common stockholders	11	57	11
Reallocation of net income attributable to participating securities	0	31	30
Reallocation of net income as a result of conversion of Class B to Class A common stock	21	611	361
Reallocation of net income to Class B common stock	0	0	0
Net income attributable to common stockholders for diluted EPS	32	699	402
Denominator
Number of shares used for basic EPS computation	667	110	32
Conversion of Class B to Class A common stock	1,339	1,184	1,075
Shares subject to repurchase	3	3	4
Warrants	0	2	8
Number of shares used for diluted EPS computation	2,166	1,508	1,414
Diluted EPS	$ 0.01	$ 0.46	$ 0.28
Class A Common Stock | Employee Stock Option
Denominator
Share based payment arrangements	134	204	295
Class A Common Stock | Restricted Stock Units (RSUs)
Denominator
Share based payment arrangements	23	5	0
Class B Common Stock
Numerator
Net income	35	915	588
Less: Net income attributable to participating securities	14	304	227
Net income attributable to Class A and Class B common stockholders	21	611	361
Denominator
Weighted average shares outstanding	1,344	1,189	1,081
Less: Shares subject to repurchase	5	5	6
Number of shares used for basic EPS computation	1,339	1,184	1,075
Basic EPS	$ 0.02	$ 0.52	$ 0.34
Numerator
Net income attributable to Class A and Class B common stockholders	21	611	361
Reallocation of net income attributable to participating securities	0	0	0
Reallocation of net income as a result of conversion of Class B to Class A common stock	0	0	0
Reallocation of net income to Class B common stock	1	37	32
Net income attributable to common stockholders for diluted EPS	$ 22	$ 648	$ 393
Denominator
Number of shares used for basic EPS computation	1,339	1,184	1,075
Conversion of Class B to Class A common stock	0	0	0
Shares subject to repurchase	3	3	4
Warrants	0	2	8
Number of shares used for diluted EPS computation	1,499	1,398	1,382
Diluted EPS	$ 0.01	$ 0.46	$ 0.28
Class B Common Stock | Employee Stock Option
Denominator
Share based payment arrangements	134	204	295
Class B Common Stock | Restricted Stock Units (RSUs)
Denominator
Share based payment arrangements	23	5	0
Restricted Stock Units (RSUs)
Earnings Per Share, Basic, by Common Class, Including Two Class Method
Antidilutive securities excluded from computation of earnings per share	15	3
Employee Stock Option
Earnings Per Share, Basic, by Common Class, Including Two Class Method
Antidilutive securities excluded from computation of earnings per share			2