Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy of Financial Assets and Liabilities under U.S. GAAP Guidance (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Net amounts of recognized assets
Financial instruments owned, at fair value - Domestic Government debt	$ 31,175	$ 30,956
Financial instruments owned, at fair value - Foreign government debt	7,678	9,646
Financial instruments owned, at fair value - Equities	466	1
Financial instruments owned, at fair value - Equities		641
Netting and Collateral	(66,271)	(71,095)
Assets, net amounts presented in the statements of financial condition	3,762	2,879
Total	43,081	44,123
Net amounts of recognized Liabilities
Netting and Collateral	(66,271)	(71,095)
Liabilities, net amounts presented in the statements of financial condition	7,633	2,849
Contingent consideration	24,279	29,756
Total	31,912	32,605
Forwards
Net amounts of recognized assets
Netting and Collateral	(143)	(60)
Assets, net amounts presented in the statements of financial condition	603	392
Net amounts of recognized Liabilities
Netting and Collateral	(143)	(60)
Liabilities, net amounts presented in the statements of financial condition	569	419
FX swaps
Net amounts of recognized assets
Netting and Collateral	(489)	(538)
Assets, net amounts presented in the statements of financial condition	3,134	2,487
Net amounts of recognized Liabilities
Netting and Collateral	(489)	(538)
Liabilities, net amounts presented in the statements of financial condition	5,796	1,490
Futures
Net amounts of recognized assets
Netting and Collateral	(64,769)	(70,497)
Assets, net amounts presented in the statements of financial condition	0	0
Net amounts of recognized Liabilities
Netting and Collateral	(64,769)	(70,497)
Liabilities, net amounts presented in the statements of financial condition	1,268	940
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(870)
Assets, net amounts presented in the statements of financial condition	25
Net amounts of recognized Liabilities
Netting and Collateral	(870)
Liabilities, net amounts presented in the statements of financial condition	0
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value - Domestic Government debt	31,175	30,956
Financial instruments owned, at fair value - Foreign government debt	0	0
Financial instruments owned, at fair value - Equities	466	0
Financial instruments owned, at fair value - Equities		641
Total	31,641	31,597
Net amounts of recognized Liabilities
Contingent consideration	0	0
Total	0	0
Level 1 | Forwards
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	0
Level 1 | FX swaps
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	0
Level 1 | Futures
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	0
Level 1 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	0
Net amounts of recognized Liabilities
Derivative liability	0
Level 2
Net amounts of recognized assets
Financial instruments owned, at fair value - Domestic Government debt	0	0
Financial instruments owned, at fair value - Foreign government debt	7,678	9,646
Financial instruments owned, at fair value - Equities	0	1
Financial instruments owned, at fair value - Equities		0
Total	77,711	83,621
Net amounts of recognized Liabilities
Contingent consideration	0	0
Total	73,904	73,944
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	746	452
Net amounts of recognized Liabilities
Derivative liability	712	479
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	3,623	3,025
Net amounts of recognized Liabilities
Derivative liability	6,285	2,028
Level 2 | Futures
Net amounts of recognized assets
Derivative asset	64,769	70,497
Net amounts of recognized Liabilities
Derivative liability	66,037	71,437
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	895
Net amounts of recognized Liabilities
Derivative liability	870
Level 3
Net amounts of recognized assets
Financial instruments owned, at fair value - Domestic Government debt	0	0
Financial instruments owned, at fair value - Foreign government debt	0	0
Financial instruments owned, at fair value - Equities	0	0
Financial instruments owned, at fair value - Equities		0
Total	0	0
Net amounts of recognized Liabilities
Contingent consideration	24,279	29,756
Total	24,279	29,756
Level 3 | Forwards
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	0
Level 3 | FX swaps
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	0
Level 3 | Futures
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	$ 0
Level 3 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	0
Net amounts of recognized Liabilities
Derivative liability	$ 0