Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy of Financial Assets and Liabilities under U.S. GAAP Guidance (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	$ 31,943	$ 31,175
Financial instruments owned, at fair value—Foreign government debt	8,850	7,678
Financial instruments owned, at fair value—Equities	489	466
Financial instruments owned, at fair value—Corporate bonds	20
Netting and Collateral	(68,234)	(66,271)
Net amounts presented in the statements of financial condition, assets	7,045	3,762
Total	48,347	43,081
Net amounts of recognized Liabilities
Netting and Collateral	(68,234)	(66,271)
Net amounts presented in the statements of financial condition, liabilities	7,568	7,633
Contingent consideration	27,673	24,279
Total	35,241	31,912
FX swaps
Net amounts of recognized assets
Netting and Collateral	(541)	(489)
Net amounts presented in the statements of financial condition, assets	6,453	3,134
Net amounts of recognized Liabilities
Netting and Collateral	(541)	(489)
Net amounts presented in the statements of financial condition, liabilities	5,662	5,796
Forwards
Net amounts of recognized assets
Netting and Collateral	(24)	(143)
Net amounts presented in the statements of financial condition, assets	564	603
Net amounts of recognized Liabilities
Netting and Collateral	(24)	(143)
Net amounts presented in the statements of financial condition, liabilities	977	569
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(19,682)
Net amounts presented in the statements of financial condition, assets	28	25
Net amounts of recognized Liabilities
Netting and Collateral	(19,682)	(870)
Net amounts presented in the statements of financial condition, liabilities	0	0
Futures
Net amounts of recognized assets
Netting and Collateral	(47,987)	(64,769)
Net amounts presented in the statements of financial condition, assets	0	0
Net amounts of recognized Liabilities
Netting and Collateral	(47,987)	(64,769)
Net amounts presented in the statements of financial condition, liabilities	929	1,268
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	31,943	31,175
Financial instruments owned, at fair value—Foreign government debt	0	0
Financial instruments owned, at fair value—Equities	489	466
Financial instruments owned, at fair value—Corporate bonds	0
Total	32,432	31,641
Net amounts of recognized Liabilities
Contingent consideration	0	0
Total	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 | Forwards
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	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 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	8,850	7,678
Financial instruments owned, at fair value—Equities	0	0
Financial instruments owned, at fair value—Corporate bonds	20
Total	84,149	77,711
Net amounts of recognized Liabilities
Contingent consideration	0	0
Total	75,802	73,904
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	6,994	3,623
Net amounts of recognized Liabilities
Derivative liability	6,203	6,285
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	588	746
Net amounts of recognized Liabilities
Derivative liability	1,001	712
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	19,710	895
Net amounts of recognized Liabilities
Derivative liability	19,682	870
Level 2 | Futures
Net amounts of recognized assets
Derivative asset	47,987	64,769
Net amounts of recognized Liabilities
Derivative liability	48,916	66,037
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—Corporate bonds	0
Total	0	0
Net amounts of recognized Liabilities
Contingent consideration	27,673	24,279
Total	27,673	24,279
Level 3 | FX swaps
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	0	0
Level 3 | Forwards
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	0
Level 3 | Futures
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized Liabilities
Derivative liability	$ 0	$ 0