Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	$ 13,693	$ 5,314	$ 11,739
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	(301)	2,526	3,032
TBA Residential Mortgage-Backed Securities Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	1,070	(4,047)	1,685
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0
Interest Rate Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	3,458	3,193	1,099
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0		0
Energy Commodity [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	8,171	5,262	7,951
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0
Agricultural Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	382	341	629
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0
Foreign Exchange [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	612	565	375
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0
Equity Swap [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	0	0	0
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0
Customer Derivative Trading [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	13,693	5,314	11,739
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0
Interest Rate Risk Management Trading New [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	0	0	0
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	$ (301)	$ 2,526	$ 3,032