Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy of Financial Assets and Liabilities under U.S. GAAP Guidance (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Net amounts of recognized assets
Marketable securities	$ 348	$ 349
Government debt	36,129	57,918
Securities owned—Equities	232	75
FX/commodities options		74
Forwards	246	295
FX swaps	3,923	562
Futures	0	0
Corporate bonds	1,069	579
Total	41,947	59,852
Net amounts of recognized Liabilities
FX swaps	4,192	319
Forwards	1,059	215
Futures	1,214	926
Contingent consideration	27,484	39,791
Total	33,949	41,251
Netting and Collateral
Net amounts of recognized assets
Marketable securities	0	0
Government debt	0	0
Securities owned—Equities	0	0
FX/commodities options		0
Forwards	(118)	(43)
FX swaps	(622)	(21)
Futures	(116,427)	(41,257)
Corporate bonds	0	0
Total	(117,167)	(41,321)
Net amounts of recognized Liabilities
FX swaps	(622)	(21)
Forwards	(118)	(43)
Futures	(116,427)	(41,257)
Contingent consideration	0	0
Total	(117,167)	(41,321)
Level 1
Net amounts of recognized assets
Marketable securities	348	349
Government debt	36,129	57,918
Securities owned—Equities	232	75
FX/commodities options		74
Forwards	0	0
FX swaps	0	0
Futures	0	0
Corporate bonds	0	0
Total	36,709	58,416
Net amounts of recognized Liabilities
FX swaps	0	0
Forwards	0	0
Futures	0	0
Contingent consideration	0	0
Total	0	0
Level 2
Net amounts of recognized assets
Marketable securities	0	0
Government debt	0	0
Securities owned—Equities	0	0
FX/commodities options		0
Forwards	364	338
FX swaps	4,545	583
Futures	116,427	41,257
Corporate bonds	1,069	579
Total	122,405	42,757
Net amounts of recognized Liabilities
FX swaps	4,814	340
Forwards	1,177	258
Futures	117,641	42,183
Contingent consideration	0	0
Total	123,632	42,781
Level 3
Net amounts of recognized assets
Marketable securities	0	0
Government debt	0	0
Securities owned—Equities	0	0
FX/commodities options		0
Forwards	0	0
FX swaps	0	0
Futures	0	0
Corporate bonds	0	0
Total	0	0
Net amounts of recognized Liabilities
FX swaps	0	0
Forwards	0	0
Futures	0	0
Contingent consideration	27,484	39,791
Total	$ 27,484	$ 39,791

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