Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	$ 1,500	$ 2,831
Gain (Loss) on Derivatives, Net	968	6,118
To-be-announced residential mortgage-backed securities [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	(160)	(15)
Gain (Loss) on Derivatives, Net	0	0
Interest rate swaps [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	507	767
Gain (Loss) on Derivatives, Net	0	0
Energy contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	871	1,783
Gain (Loss) on Derivatives, Net	0	0
Agricultural contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	63	108
Gain (Loss) on Derivatives, Net	0	0
Foreign exchange contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	219	188
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
Customer risk management programs [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	1,500	2,831
Gain (Loss) on Derivatives, Net	0	0
Interest rate risk management programs [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	0	0
Gain (Loss) on Derivatives, Net	$ 968	$ 6,118