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, 2025	Dec. 31, 2024
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	$ 121,587	$ 170,381
Financial instruments owned, at fair value—Foreign government debt	16,705	14,827
Financial instruments owned, at fair value—Equities	1,118	989
Financial instruments owned, at fair value—Corporate bonds	60
Netting and Collateral	(61,061)	(38,289)
Net amounts presented in the statements of financial condition, assets	1,316	5,384
Total	140,786	191,581
Net amounts of recognized liabilities
Netting and Collateral	(61,061)	(38,289)
Net amounts presented in the statements of financial condition, liabilities	2,259	4,430
Contingent consideration	23,108	21,768
Total	25,367	26,198
FX swaps
Net amounts of recognized assets
Netting and Collateral	(141)	(1,183)
Net amounts presented in the statements of financial condition, assets	901	4,810
Net amounts of recognized liabilities
Netting and Collateral	(141)	(1,183)
Net amounts presented in the statements of financial condition, liabilities	1,217	3,679
Forwards
Net amounts of recognized assets
Netting and Collateral	(94)	(56)
Net amounts presented in the statements of financial condition, assets	397	409
Net amounts of recognized liabilities
Netting and Collateral	(94)	(56)
Net amounts presented in the statements of financial condition, liabilities	216	751
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(1,584)	(132)
Net amounts presented in the statements of financial condition, assets	18	0
Net amounts of recognized liabilities
Netting and Collateral	(1,584)	(132)
Net amounts presented in the statements of financial condition, liabilities	0	0
Futures
Net amounts of recognized assets
Netting and Collateral	(59,242)	(36,918)
Net amounts presented in the statements of financial condition, assets	0	165
Net amounts of recognized liabilities
Netting and Collateral	(59,242)	(36,918)
Net amounts presented in the statements of financial condition, liabilities	826	0
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	121,587	170,381
Financial instruments owned, at fair value—Foreign government debt	0	0
Financial instruments owned, at fair value—Equities	1,118	989
Financial instruments owned, at fair value—Corporate bonds	0
Total	181,947	208,453
Net amounts of recognized liabilities
Contingent consideration	0	0
Total	60,068	36,918
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	59,242	37,083
Net amounts of recognized liabilities
Derivative liability	60,068	36,918
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	16,705	14,827
Financial instruments owned, at fair value—Equities	0	0
Financial instruments owned, at fair value—Corporate bonds	60
Total	19,900	21,417
Net amounts of recognized liabilities
Contingent consideration	0	0
Total	3,252	5,801
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	1,042	5,993
Net amounts of recognized liabilities
Derivative liability	1,358	4,862
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	491	465
Net amounts of recognized liabilities
Derivative liability	310	807
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	1,602	132
Net amounts of recognized liabilities
Derivative liability	1,584	132
Level 2 | Futures
Net amounts of recognized assets
Derivative asset	0	0
Net amounts of recognized liabilities
Derivative liability	0	0
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	23,108	21,768
Total	23,108	21,768
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	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