Stockholders' Equity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		12 Months Ended		9 Months Ended				1 Months Ended
	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2012 2012 Plan	Sep. 30, 2012 2012 Plan Minimum	Sep. 30, 2012 2012 Plan Maximum	Sep. 30, 2012 2005 Officer's Stock Plan	Nov. 30, 2005 2005 Officer's Stock Plan Class B Common Stock
Stockholders Equity Note
Shares reserved for issuance increase date						Jan. 01, 2013	Jan. 01, 2022
Shares Reserved For Issuance Increase Percentage					2.50%
Maximum term for stock options granted					10 years			10 years
Shares of incentive and nonstatutory stock options provided for issuance								120,000,000
Non statutory stock option issued to CEO to purchase shares of Class B common stock									120,000,000
Options partially exercised and fully vested								60,000,000
Number of Shares
Beginning Balance	258,539,000
Stock options exercised	(84,568,000)
Stock options forfeited/cancelled	(584,000)
Ending Balance	173,387,000		258,539,000
Shares Available for Grant
Beginning Balance	52,318,000
RSUs granted	(33,865,000)
Stock options exercised	0
Stock options forfeited/cancelled	584,000
RSUs forfeited and cancelled	9,089,000
2012 Equity Incentive Plan shares authorized	25,000,000
Ending Balance	53,126,000		52,318,000
Weighted Average Exercise Price
Beginning Balance	$ 0.47
Stock options exercised	$ 0.11
Stock options forfeited/cancelled	$ 0.62
Ending Balance	$ 0.65		$ 0.47
Weighted-Average Remaining Contractual Term
Beginning Balance	3 years 10 months		4 years 4 months 17 days
Aggregate Intrinsic Value
Beginning Balance	$ 7,360	[1]
Ending Balance	$ 3,643	[1]	$ 7,360	[1]
Outstanding RSUs
Beginning Balance	378,772,000
RSUs granted	33,865,000
RSUs forfeited and cancelled	(9,089,000)
Ending Balance	403,548,000		378,772,000
Weighted Average Grant Date Fair Value
Beginning Balance	$ 6.83
RSUs granted	$ 34.69
RSUs forfeited and cancelled	$ 19.32
Ending Balance	$ 8.89		$ 6.83

[1] e aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock option awards and the assessed fair value of our common stock as of December 31, 2011 and the closing price of our common stock on September 30, 2012.