Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		$ (65,407)	$ 90,031
Gain (Loss) on Derivatives, Net		9,565	(8,633)
Total customer risk management programs
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		8,389	6,325
Gain (Loss) on Derivatives, Net		0	0
Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		741	2,460
Gain (Loss) on Derivatives, Net		0	0
Energy contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		7,610	3,815
Gain (Loss) on Derivatives, Net		0	0
Foreign exchange contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		38	50
Gain (Loss) on Derivatives, Net		0	0
Equity option contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		0	0
Gain (Loss) on Derivatives, Net		0	0
Trading [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	[1]	(73,796)	83,706
Gain (Loss) on Derivatives, Net	[1]	0	0
Internal risk management programs [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue		0	0
Gain (Loss) on Derivatives, Net		$ 9,565	$ (8,633)

[1] Represents changes in fair value of to-be-announced securities and other derivative instruments held to mitigate market risk of trading securities portfolio, which is offset by changes in fair value of trading securities also included in Brokerage and Trading Revenue in the Consolidated Statements of Earnings.