Certain Balance Sheet Accounts - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 94,650	$ 92,449
Less accumulated depreciation	(67,618)	(62,512)
Total property and equipment, net	27,032	29,937
Computers and Equipment [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	17,191	18,337
Computer Software [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	35,476	30,812
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	10,466	10,365
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	$ 31,517	$ 32,935