Investment Securities (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Roll-Forward Of Credit-Related Other-Than-Temporary Impairment Recognized In Earnings
Beginning Balance	$ 1,227
Addition of OTTI that was not previously recognized	656
Reduction for securities sold during the period
Addition of OTTI that was previously recognized because the security might not be sold before recovery of its amortized cost basis
Reduction for increases in cash flows expected to be collected that are recognized over the remaining life of the security
Ending Balance	$ 1,883