Stock-Based Awards and Stock-Based Compensation - Stock-Based Compensation Expense Included in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	$ 20,305	$ 32,908	$ 34,754
Computers, equipment and software [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	0	1,370	0
Stock-based awards to non-employees [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation related to non-employee awards (included in total stock-based compensation above)	0	41	488
Cost of revenues [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	3,029	4,276	3,450
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	7,078	10,642	14,133
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	3,775	10,852	10,614
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated stock-based compensation expense	$ 6,423	$ 7,138	$ 6,557