Fair value measurements - Schedule of Fair Value Amounts of Derivative Instruments and their Effect on Consolidated Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in Income on Derivatives (pre-tax)	$ (5,894)	$ 1,103	$ (1,480)	$ 4,872
Commodity contracts | Principal transactions revenue, net | Futures
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in Income on Derivatives (pre-tax)	(5,892)	1,078	(1,457)	4,817
Other contracts | Principal transactions revenue, net | TBAs
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in Income on Derivatives (pre-tax)	$ (2)	$ 25	1	63
Other contracts | Other revenue/(Compensation and related expenses) | Foreign exchange forward contracts
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in Income on Derivatives (pre-tax)			$ (24)	$ (8)