Certain Balance Sheet Accounts - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Total property and equipment	$ 76,163	$ 74,626
Less accumulated depreciation	48,594	42,452
Total	27,569	32,174
Computers and Equipment [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	18,177	17,785
Computer Software [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	23,899	22,399
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	8,527	8,627
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	$ 25,560	$ 25,815