Numerators and Denominators of Basic and Diluted EPS Computations for Common Stock (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator
Net (loss) income	$ (157)	$ 240	$ 48	$ 471
Less: Net income attributable to participating securities	0	81	21	160
Net (loss) income attributable to common stockholders	(157)	159	27	311
Denominator
Number of shares used for basic EPS computation	1,879	1,292	1,613	1,267
Basic EPS	$ (0.08)	$ 0.12	$ 0.02	$ 0.25
Numerator
Net (loss) income attributable to common stockholders	(157)	159	27	311
Denominator
Number of shares used for basic EPS computation	1,879	1,292	1,613	1,267
Number of shares used for diluted EPS computation	1,879	1,510	1,792	1,499
Diluted EPS	$ (0.08)	$ 0.11	$ 0.02	$ 0.22
Common Class A
Numerator
Net (loss) income	(31)	20	7	39
Less: Net income attributable to participating securities	0	7	3	13
Net (loss) income attributable to common stockholders	(31)	13	4	26
Denominator
Weighted average shares outstanding	377	110	247	105
Less: Shares subject to repurchase	1	1	1	0
Number of shares used for basic EPS computation	376	109	246	105
Basic EPS	$ (0.08)	$ 0.12	$ 0.02	$ 0.25
Numerator
Net (loss) income attributable to common stockholders	(31)	13	4	26
Reallocation of net income attributable to participating securities	0	8	1	16
Reallocation of net (loss) income as a result of conversion of Class B to Class A common stock	(126)	146	23	285
Reallocation of net income to Class B common stock	0	0	0	0
Net (loss) income attributable to common stockholders for diluted EPS	(157)	167	28	327
Denominator
Number of shares used for basic EPS computation	376	109	246	105
Conversion of Class B to Class A common stock	1,503	1,183	1,367	1,162
Shares subject to repurchase	0	4	2	4
Warrants	0	2	0	3
Number of shares used for diluted EPS computation	1,879	1,510	1,792	1,499
Diluted EPS	$ (0.08)	$ 0.11	$ 0.02	$ 0.22
Common Class A | Employee Stock Option
Denominator
Share based payment arrangements	0	206	155	223
Common Class A | Restricted Stock
Denominator
Share based payment arrangements	0	6	22	2
Common Class B
Numerator
Net (loss) income	(126)	220	41	432
Less: Net income attributable to participating securities	0	74	18	147
Net (loss) income attributable to common stockholders	(126)	146	23	285
Denominator
Weighted average shares outstanding	1,505	1,188	1,369	1,167
Less: Shares subject to repurchase	2	5	2	5
Number of shares used for basic EPS computation	1,503	1,183	1,367	1,162
Basic EPS	$ (0.08)	$ 0.12	$ 0.02	$ 0.25
Numerator
Net (loss) income attributable to common stockholders	(126)	146	23	285
Reallocation of net income attributable to participating securities	0	0	0	0
Reallocation of net (loss) income as a result of conversion of Class B to Class A common stock	0	0	0	0
Reallocation of net income to Class B common stock	0	9	1	19
Net (loss) income attributable to common stockholders for diluted EPS	$ (126)	$ 155	$ 24	$ 304
Denominator
Number of shares used for basic EPS computation	1,503	1,183	1,367	1,162
Conversion of Class B to Class A common stock	0	0	0	0
Shares subject to repurchase	0	4	2	4
Warrants	0	2	0	3
Number of shares used for diluted EPS computation	1,503	1,401	1,546	1,394
Diluted EPS	$ (0.08)	$ 0.11	$ 0.02	$ 0.22
Common Class B | Employee Stock Option
Denominator
Share based payment arrangements	0	206	155	223
Common Class B | Restricted Stock
Denominator
Share based payment arrangements	0	6	22	2