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, 2024	Dec. 31, 2023
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	$ 31,388	$ 31,141
Financial instruments owned, at fair value—Foreign government debt	16,343	14,164
Financial instruments owned, at fair value—Equities	780	487
Financial instruments owned, at fair value—Corporate bonds	394
Netting and Collateral	(79,449)	(75,718)
Net amounts presented in the statements of financial condition, assets	4,989	3,607
Total	53,894	49,399
Net amounts of recognized liabilities
Netting and Collateral	(79,449)	(75,718)
Net amounts presented in the statements of financial condition, liabilities	3,085	5,756
Contingent consideration	9,727	11,929
Total	12,812	17,685
FX swaps
Net amounts of recognized assets
Netting and Collateral	(596)	(793)
Net amounts presented in the statements of financial condition, assets	4,067	2,674
Net amounts of recognized liabilities
Netting and Collateral	(596)	(793)
Net amounts presented in the statements of financial condition, liabilities	2,408	5,119
Forwards
Net amounts of recognized assets
Netting and Collateral	(30)	(50)
Net amounts presented in the statements of financial condition, assets	831	805
Net amounts of recognized liabilities
Netting and Collateral	(30)	(50)
Net amounts presented in the statements of financial condition, liabilities	616	609
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(9,268)
Net amounts presented in the statements of financial condition, assets	91	128
Net amounts of recognized liabilities
Netting and Collateral	(9,268)	(12,182)
Net amounts presented in the statements of financial condition, liabilities	0	0
Futures
Net amounts of recognized assets
Netting and Collateral	(69,555)	(62,693)
Net amounts presented in the statements of financial condition, assets	0	0
Net amounts of recognized liabilities
Netting and Collateral	(69,555)	(62,693)
Net amounts presented in the statements of financial condition, liabilities	61	28
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	31,388	31,141
Financial instruments owned, at fair value—Foreign government debt	0	0
Financial instruments owned, at fair value—Equities	780	487
Financial instruments owned, at fair value—Corporate bonds	0
Total	101,723	31,628
Net amounts of recognized liabilities
Contingent consideration	0	0
Total	69,616	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	69,555	0
Net amounts of recognized liabilities
Derivative liability	69,616	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	16,343	14,164
Financial instruments owned, at fair value—Equities	0	0
Financial instruments owned, at fair value—Corporate bonds	394
Total	31,620	93,489
Net amounts of recognized liabilities
Contingent consideration	0	0
Total	12,918	81,474
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	4,663	3,467
Net amounts of recognized liabilities
Derivative liability	3,004	5,912
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	861	855
Net amounts of recognized liabilities
Derivative liability	646	659
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	9,359	12,310
Net amounts of recognized liabilities
Derivative liability	9,268	12,182
Level 2 | Futures
Net amounts of recognized assets
Derivative asset	0	62,693
Net amounts of recognized liabilities
Derivative liability	0	62,721
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	9,727	11,929
Total	9,727	11,929
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