Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy of Financial Assets and Liabilities under U.S. GAAP Guidance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Net amounts of recognized assets
Financial instruments owned, at fair value - Domestic government debt	$ 31,141	$ 31,175
Financial instruments owned, at fair value - Foreign government debt	14,164	7,678
Financial instruments owned, at fair value - Equities	487
Financial instruments owned, at fair value - Equities		466
Netting and Collateral	(75,718)	(66,271)
Assets, net amounts presented in the statements of financial condition	3,607	3,762
Total	49,399	43,081
Net amounts of recognized Liabilities
Netting and Collateral	(75,718)	(66,271)
Liabilities, net amounts presented in the statements of financial condition	5,756	7,633
Contingent consideration	11,929	24,279
Total	17,685	31,912
Assets, gross amounts offset	(75,718)	(66,271)
Goodwill, purchase accounting adjustments	(1,493)
Trident
Net amounts of recognized Liabilities
Goodwill, purchase accounting adjustments	2,200
Forwards
Net amounts of recognized assets
Netting and Collateral	(50)	(143)
Assets, net amounts presented in the statements of financial condition	805	603
Net amounts of recognized Liabilities
Netting and Collateral	(50)	(143)
Liabilities, net amounts presented in the statements of financial condition	609	569
FX swaps
Net amounts of recognized assets
Netting and Collateral	(793)	(489)
Assets, net amounts presented in the statements of financial condition	2,674	3,134
Net amounts of recognized Liabilities
Netting and Collateral	(793)	(489)
Liabilities, net amounts presented in the statements of financial condition	5,119	5,796
Assets, gross amounts offset	(793)	(489)
Futures
Net amounts of recognized assets
Netting and Collateral	(62,693)	(64,769)
Assets, net amounts presented in the statements of financial condition	0	0
Net amounts of recognized Liabilities
Netting and Collateral	(62,693)	(64,769)
Liabilities, net amounts presented in the statements of financial condition	28	1,268
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(12,182)
Assets, net amounts presented in the statements of financial condition	128	25
Net amounts of recognized Liabilities
Netting and Collateral	(12,182)	(870)
Liabilities, net amounts presented in the statements of financial condition	0	0
Assets, gross amounts offset	(12,182)	(870)
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value - Domestic government debt	31,141	31,175
Financial instruments owned, at fair value - Foreign government debt	0	0
Financial instruments owned, at fair value - Equities	487
Financial instruments owned, at fair value - Equities		466
Total	31,628	31,641
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	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	14,164	7,678
Financial instruments owned, at fair value - Equities	0
Financial instruments owned, at fair value - Equities		0
Total	93,489	77,711
Net amounts of recognized Liabilities
Contingent consideration	0	0
Total	81,474	73,904
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	855	746
Net amounts of recognized Liabilities
Derivative liability	659	712
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	3,467	3,623
Net amounts of recognized Liabilities
Derivative liability	5,912	6,285
Level 2 | Futures
Net amounts of recognized assets
Derivative asset	62,693	64,769
Net amounts of recognized Liabilities
Derivative liability	62,721	66,037
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	12,310	895
Net amounts of recognized Liabilities
Derivative liability	12,182	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
Financial instruments owned, at fair value - Equities		0
Total	0	0
Net amounts of recognized Liabilities
Contingent consideration	11,929	24,279
Total	11,929	24,279
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	0
Net amounts of recognized Liabilities
Derivative liability	$ 0	$ 0