Stockholders' Equity - Stock-Based Expense Related to Grants of Employee and Consultant Stock Options, Warrants, Restricted Stock and ZSUs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based expense	$ 9,256	$ 37,817	$ 65,066	$ 267,124
Cost of revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based expense	(645)	1,080	(351)	11,098
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based expense	10,119	41,853	46,907	185,245
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based expense	2,941	(3,977)	8,327	21,156
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based expense	$ (3,159)	$ (1,139)	$ 10,183	$ 49,625