Fixed Assets, Net - Components of Fixed Assets, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 482,374	$ 478,683
Less: accumulated depreciation and amortization	(292,262)	(262,659)
Fixed assets, net	190,112	216,024
Computer and communications equipment
Property, Plant and Equipment [Line Items]
Fixed assets, gross	96,472	92,577
Software, including software development costs
Property, Plant and Equipment [Line Items]
Fixed assets, gross	280,540	265,082
Leasehold improvements and other fixed assets
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 105,362	$ 121,024