Fixed Assets, Net - Components of Fixed Assets, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 562,702	$ 510,880
Less: accumulated depreciation and amortization	(384,402)	(327,402)
Fixed assets, net	178,300	183,478
Computer and communications equipment
Property, Plant and Equipment [Line Items]
Fixed assets, gross	103,621	95,730
Software, including software development costs
Property, Plant and Equipment [Line Items]
Fixed assets, gross	360,047	320,275
Leasehold improvements and other fixed assets
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 99,034	$ 94,875