Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	$ 1,998	$ 3,327	$ 10,861	$ 5,600
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	464	4,048	336	2,700
TBA Residential Mortgage-Backed Securities Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	(803)	1,225	504	(2,829)
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0	0
Interest Rate Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	706	484	2,850	2,026
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	1,856	1,360	6,754	5,759
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0	0
Agricultural Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	115	103	298	263
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0	0
Foreign Exchange [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	124	155	455	381
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0	0
Equity Swap [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	0	0	0	0
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	0	0	0
Customer Derivative Trading [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokergage and Trading Revenue	1,998	3,327	10,861	5,600
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	0	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	0
Derivative Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) on Derivatives, Net	$ 464	$ 4,048	$ 336	$ 2,700