Receivables - Schedule of Activity in Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Allowance For Doubtful Accounts Receivable Rollforward
Allowance for doubtful accounts receivables, Beginning balance		$ 36,649	$ 27,130
Adjustment for adoption of new accounting guidance			7,575
Bad debt expense, net of reversals		375	(527)
Charge-offs, foreign currency translation and other adjustments		(2,022)	(2,891)
Allowance for doubtful accounts receivables, Ending balance	[1]	$ 35,002	$ 31,287

[1] The allowance for doubtful accounts balances are substantially all related to M&A and Restructuring fee receivables that include recoverable expense receivables.