Allowance for Credit Losses - Loan Portfolio by Impairment Methodology (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	$ 399,722	$ 428,159
Ending balance: individually evaluated for impairment	17,784	23,644
Ending balance: collectively evaluated for impairment	381,938	404,515
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	113,077	108,047
Ending balance: individually evaluated for impairment	2,464	3,857
Ending balance: collectively evaluated for impairment	110,613	104,190
Real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	234,185	259,241
Ending balance: individually evaluated for impairment	13,454	17,359
Ending balance: collectively evaluated for impairment	220,731	241,882
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	52,460	60,871
Ending balance: individually evaluated for impairment	1,866	2,428
Ending balance: collectively evaluated for impairment	$ 50,594	$ 58,443