Fixed Assets, Net - Components of Fixed Assets, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 536,537	$ 510,880
Less: accumulated depreciation and amortization	(353,913)	(327,402)
Fixed assets, net	182,624	183,478
Computer and communications equipment
Property, Plant and Equipment [Line Items]
Fixed assets, gross	100,539	95,730
Software, including software development costs
Property, Plant and Equipment [Line Items]
Fixed assets, gross	340,323	320,275
Leasehold improvements and other fixed assets
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 95,675	$ 94,875