Loans and Allowance for Loan Losses - Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, Total	$ 27,137		$ 26,167
Unpaid Principal Balance, Total	34,547		34,156
Related Allowance, Total	1,970		1,673
Average Recorded Balance, Total	26,563	30,430
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment	19,035		15,378
Unpaid Principal Balance	24,826		20,086
Related Allowance	0		0
Average Recorded Balance	17,207	9,786
Recorded Investment	4,906		7,942
Unpaid Principal Balance	5,867		9,876
Related Allowance	1,778		1,449
Average Recorded Balance	6,424	18,567
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment	123		138
Unpaid Principal Balance	294		138
Related Allowance	0		0
Average Recorded Balance	130	287
Recorded Investment	441		459
Unpaid Principal Balance	442		459
Related Allowance	192		209
Average Recorded Balance	450	269
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment	1,991		1,610
Unpaid Principal Balance	2,209		1,686
Related Allowance	0		0
Average Recorded Balance	1,800	1,449
Recorded Investment	0		181
Unpaid Principal Balance	0		1,452
Related Allowance	0		15
Average Recorded Balance	0	72
Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment	483		398
Unpaid Principal Balance	689		398
Related Allowance	0		0
Average Recorded Balance	441	0
Recorded Investment	0		0
Unpaid Principal Balance	0		0
Related Allowance	0		0
Average Recorded Balance		0
Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment	99		0
Unpaid Principal Balance	161		0
Related Allowance	0		0
Average Recorded Balance	50	0
Recorded Investment	0		0
Unpaid Principal Balance	0		0
Related Allowance	0		0
Average Recorded Balance	0	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment	59		61
Unpaid Principal Balance	59		61
Related Allowance	0		0
Average Recorded Balance	61	0
Recorded Investment	0		0
Unpaid Principal Balance	0		0
Related Allowance	0		0
Average Recorded Balance	$ 0	$ 0