Fair Value of Financial Assets and Liabilities - Fair Value Hierarchy of Financial Assets and Liabilities under U.S. GAAP Guidance (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	$ 128,739	$ 170,381
Financial instruments owned, at fair value—Foreign government debt	19,967	14,827
Financial instruments owned, at fair value—Equities	900	989
Financial instruments owned, at fair value—Corporate bonds	173
Netting and Collateral	(45,807)	(38,289)
Net amounts presented in the statements of financial condition, assets	1,152	5,384
Total	150,931	191,581
Net amounts of recognized liabilities
Netting and Collateral	(45,807)	(38,289)
Net amounts presented in the statements of financial condition, liabilities	1,750	4,430
Contingent consideration	22,977	21,768
Total	24,727	26,198
FX swaps
Net amounts of recognized assets
Netting and Collateral	(322)	(1,183)
Net amounts presented in the statements of financial condition, assets	540	4,810
Net amounts of recognized liabilities
Netting and Collateral	(322)	(1,183)
Net amounts presented in the statements of financial condition, liabilities	680	3,679
Forwards
Net amounts of recognized assets
Netting and Collateral	(119)	(56)
Net amounts presented in the statements of financial condition, assets	386	409
Net amounts of recognized liabilities
Netting and Collateral	(119)	(56)
Net amounts presented in the statements of financial condition, liabilities	682	751
Interest rate swaps
Net amounts of recognized assets
Netting and Collateral	(8,765)	(132)
Net amounts presented in the statements of financial condition, assets	226	0
Net amounts of recognized liabilities
Netting and Collateral	(8,765)	(132)
Net amounts presented in the statements of financial condition, liabilities	0	0
Futures
Net amounts of recognized assets
Netting and Collateral	(36,601)	(36,918)
Net amounts presented in the statements of financial condition, assets	0	165
Net amounts of recognized liabilities
Netting and Collateral	(36,601)	(36,918)
Net amounts presented in the statements of financial condition, liabilities	388	0
Level 1
Net amounts of recognized assets
Financial instruments owned, at fair value—Domestic government debt	128,739	170,381
Financial instruments owned, at fair value—Foreign government debt	0	0
Financial instruments owned, at fair value—Equities	900	989
Financial instruments owned, at fair value—Corporate bonds	0
Total	166,240	208,453
Net amounts of recognized liabilities
Contingent consideration	0	0
Total	36,989	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	36,601	37,083
Net amounts of recognized liabilities
Derivative liability	36,989	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	19,967	14,827
Financial instruments owned, at fair value—Equities	0	0
Financial instruments owned, at fair value—Corporate bonds	173
Total	30,498	21,417
Net amounts of recognized liabilities
Contingent consideration	0	0
Total	10,568	5,801
Level 2 | FX swaps
Net amounts of recognized assets
Derivative asset	862	5,993
Net amounts of recognized liabilities
Derivative liability	1,002	4,862
Level 2 | Forwards
Net amounts of recognized assets
Derivative asset	505	465
Net amounts of recognized liabilities
Derivative liability	801	807
Level 2 | Interest rate swaps
Net amounts of recognized assets
Derivative asset	8,991	132
Net amounts of recognized liabilities
Derivative liability	8,765	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	22,977	21,768
Total	22,977	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