Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy of Financial Assets and Liabilities under U.S. GAAP Guidance (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	$ 32,102	$ 31,175
Financial instruments owned, at fair value—Foreign government debt	7,801	7,678
Financial instruments owned, at fair value—Equities	616	466
Netting and Collateral	(85,875)	(66,271)
Net amounts presented in the statements of financial condition, assets	5,201	3,762
Total	45,720	43,081
Net amounts of recognized Liabilities
Netting and Collateral	(85,875)	(66,271)
Net amounts presented in the statements of financial condition, liabilities	4,000	7,633
Contingent consideration	8,909	24,279
Total	12,909	31,912
FX swaps
Net amounts of recognized assets
Netting and Collateral	(256)	(489)
Net amounts presented in the statements of financial condition, assets	4,386	3,134
Net amounts of recognized Liabilities
Netting and Collateral	(256)	(489)
Net amounts presented in the statements of financial condition, liabilities	2,534	5,796
Forwards
Net amounts of recognized assets
Netting and Collateral	(51)	(143)
Net amounts presented in the statements of financial condition, assets	598	603
Net amounts of recognized Liabilities
Netting and Collateral	(51)	(143)
Net amounts presented in the statements of financial condition, liabilities	1,109	569
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(15,476)
Net amounts presented in the statements of financial condition, assets	217	25
Net amounts of recognized Liabilities
Netting and Collateral	(15,476)	(870)
Net amounts presented in the statements of financial condition, liabilities	0	0
Futures
Net amounts of recognized assets
Netting and Collateral	(70,092)	(64,769)
Net amounts presented in the statements of financial condition, assets	0	0
Net amounts of recognized Liabilities
Netting and Collateral	(70,092)	(64,769)
Net amounts presented in the statements of financial condition, liabilities	357	1,268
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	32,102	31,175
Financial instruments owned, at fair value—Foreign government debt	0	0
Financial instruments owned, at fair value—Equities	616	466
Total	32,718	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	7,801	7,678
Financial instruments owned, at fair value—Equities	0	0
Total	98,877	77,711
Net amounts of recognized Liabilities
Contingent consideration	0	0
Total	89,875	73,904
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	4,642	3,623
Net amounts of recognized Liabilities
Derivative liability	2,790	6,285
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	649	746
Net amounts of recognized Liabilities
Derivative liability	1,160	712
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	15,693	895
Net amounts of recognized Liabilities
Derivative liability	15,476	870
Level 2 | Futures
Net amounts of recognized assets
Derivative asset	70,092	64,769
Net amounts of recognized Liabilities
Derivative liability	70,449	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
Total	0	0
Net amounts of recognized Liabilities
Contingent consideration	8,909	24,279
Total	8,909	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