Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Derivatives in fair value hedging relationships	$ 81	$ 86	$ 103
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative instruments not designated as hedging instruments, net	0	0	0
Total derivatives	81	86	103
Interest Income Expense [Member] | Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Derivatives in fair value hedging relationships	81	86	103
Other Income [Member] | Interest rate contracts [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative instruments not designated as hedging instruments, gain	1,782	3,654	3,504
Other Expense [Member] | Interest rate contracts [Member]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net [Abstract]
Derivative instruments not designated as hedging instruments, loss	$ (1,782)	$ (3,654)	$ (3,504)