Property and Equipment, Net - Components of Company's Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 86,427	$ 85,465
Accumulated depreciation	(51,167)	(48,967)
Property and equipment, net	35,260	36,498
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	40,667	40,583
Office Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	16,603	16,234
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 29,157	$ 28,648