Loans and Allowance for Loan Losses (Allowance for loan losses, rollforward) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	$ 12,690	$ 12,455	$ 16,608
Charge-offs during period	(10,751)	(9,048)	(29,909)
Recoveries during period	1,698	1,994	1,744
Provision	4,306	7,289	24,012
Balance, end of period	7,943	12,690	12,455
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	2,817	2,925	4,785
Charge-offs during period	(2,649)	(1,366)	(10,603)
Recoveries during period	453	755	628
Provision	1,535	503	8,115
Balance, end of period	2,156	2,817	2,925
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	4,880	3,655	3,827
Charge-offs during period	(4,548)	(2,594)	(5,610)
Recoveries during period	466	293	311
Provision	1,964	3,526	5,127
Balance, end of period	2,762	4,880	3,655
Commercial construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	500	540	1,671
Charge-offs during period	(243)	(217)	(1,393)
Recoveries during period	10	3	391
Provision	(166)	174	(129)
Balance, end of period	101	500	540
Land and land development loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	2,273	2,408	2,707
Charge-offs during period	(1,601)	(3,056)	(8,622)
Recoveries during period	283	507	175
Provision	242	2,414	8,148
Balance, end of period	1,197	2,273	2,408
Agriculture
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	172	779	1,390
Charge-offs during period	(32)	(400)	(1,055)
Recoveries during period	117	103	31
Provision	(29)	(310)	413
Balance, end of period	228	172	779
Multifamily
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	91	83	26
Charge-offs during period	0	0	(16)
Recoveries during period	0	0	0
Provision	(40)	8	73
Balance, end of period	51	91	83
Residential real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	1,566	1,252	1,412
Charge-offs during period	(1,256)	(757)	(2,019)
Recoveries during period	196	157	50
Provision	638	914	1,809
Balance, end of period	1,144	1,566	1,252
Residential construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	59	65	170
Charge-offs during period	0	(34)	(101)
Recoveries during period	7	0	0
Provision	(42)	28	(4)
Balance, end of period	24	59	65
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	295	613	539
Charge-offs during period	(422)	(624)	(490)
Recoveries during period	166	176	158
Provision	163	130	406
Balance, end of period	202	295	613
Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance, beginning of year	37	135	81
Charge-offs during period	0	0	0
Recoveries during period	0	0	0
Provision	41	(98)	54
Balance, end of period	$ 78	$ 37	$ 135