Loans and Allowance for Loan Losses (Components of allowance for loan losses) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	$ 7,943	$ 12,690	$ 12,455	$ 16,608
Individually evaluated allowance	1,564	6,250
Collectively evaluated allowance	6,379	6,440
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	2,156	2,817	2,925	4,785
Individually evaluated allowance	628	1,300
Collectively evaluated allowance	1,528	1,517
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	2,762	4,880	3,655	3,827
Individually evaluated allowance	267	2,804
Collectively evaluated allowance	2,495	2,076
Commercial construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	101	500	540	1,671
Individually evaluated allowance	0	252
Collectively evaluated allowance	101	248
Land and land development loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	1,197	2,273	2,408	2,707
Individually evaluated allowance	114	728
Collectively evaluated allowance	1,083	1,545
Agriculture
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	228	172	779	1,390
Individually evaluated allowance	10	32
Collectively evaluated allowance	218	140
Multifamily
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	51	91	83	26
Individually evaluated allowance	0	0
Collectively evaluated allowance	51	91
Residential real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	1,144	1,566	1,252	1,412
Individually evaluated allowance	458	939
Collectively evaluated allowance	686	627
Residential construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	24	59	65	170
Individually evaluated allowance	0	0
Collectively evaluated allowance	24	59
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	202	295	613	539
Individually evaluated allowance	87	195
Collectively evaluated allowance	115	100
Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Total allowance	78	37	135	81
Individually evaluated allowance	0	0
Collectively evaluated allowance	$ 78	$ 37