Accounts Payable, Accrued Expenses and Other Liabilities - Components of Other Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued compensation	$ 331,288	$ 278,399
Payroll taxes payable	61,564	41,355
Contingent consideration	14,519	32,065
Credit enhancement deposit	0	25,000
Financial guarantee liability	29,581	15	$ 32
Other liabilities	$ 436,952	$ 376,834