Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 26,520	$ 24,052
Less accumulated depreciation	(18,233)	(15,964)
Net property and equipment	8,287	8,088
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	14,189	12,844
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,614	3,131
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 8,717	$ 8,077