Fixed Assets, Net - Components of Fixed Assets, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 589,813	$ 562,702
Less: accumulated depreciation and amortization	(406,926)	(384,402)
Fixed assets, net	182,887	178,300
Computer and communications equipment
Property, Plant and Equipment [Line Items]
Fixed assets, gross	107,317	103,621
Software, including software development costs
Property, Plant and Equipment [Line Items]
Fixed assets, gross	382,472	360,047
Leasehold improvements and other fixed assets
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 100,024	$ 99,034