Loans and Allowance for Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Impaired loans without a valuation allowance, Recorded Investment	$ 10,467	$ 6,274
Impaired loans without a valuation allowance, Unpaid Principal Balance	10,814	6,399
Impaired loans without a valuation allowance, Related Allowance	0	0
Impaired loans without a valuation allowance, Average Recorded Investment	8,369	8,562
Impaired loans without a valuation allowance, Interest Income Recognized	109	306
Impaired loans with a valuation allowance, Recorded Investment	7,267	8,915
Impaired loans with a valuation allowance, Unpaid Principal Balance	7,932	8,956
Impaired loans with a valuation allowance, Related Allowance	3,578	4,046
Impaired loans with a valuation allowance, Average Recorded Investment	8,090	10,564
Impaired loans with a valuation allowance, Interest Income Recognized	105	457
Total impaired loans, Recorded Investment	17,734	15,189
Total impaired loans, Unpaid Principal Balance	18,746	15,355
Total impaired loans, Related Allowance	3,578	4,046
Total impaired loans, Average Recorded Investment	16,459	19,126
Total impaired loans, Interest Income Recognized	214	763
Commercial Real Estate Mortgage [Member]
Impaired loans without a valuation allowance, Recorded Investment	5,427	3,406
Impaired loans without a valuation allowance, Unpaid Principal Balance	5,690	3,453
Impaired loans without a valuation allowance, Related Allowance	0	0
Impaired loans without a valuation allowance, Average Recorded Investment	4,416	4,389
Impaired loans without a valuation allowance, Interest Income Recognized	64	180
Impaired loans with a valuation allowance, Recorded Investment	5,099	5,807
Impaired loans with a valuation allowance, Unpaid Principal Balance	5,764	5,848
Impaired loans with a valuation allowance, Related Allowance	2,072	2,230
Impaired loans with a valuation allowance, Average Recorded Investment	5,453	6,616
Impaired loans with a valuation allowance, Interest Income Recognized	69	215
Consumer Real Estate Mortgage [Member]
Impaired loans without a valuation allowance, Recorded Investment	2,524	513
Impaired loans without a valuation allowance, Unpaid Principal Balance	2,524	540
Impaired loans without a valuation allowance, Related Allowance	0	0
Impaired loans without a valuation allowance, Average Recorded Investment	1,518	1,538
Impaired loans without a valuation allowance, Interest Income Recognized	32	52
Impaired loans with a valuation allowance, Recorded Investment	946	1,353
Impaired loans with a valuation allowance, Unpaid Principal Balance	946	1,353
Impaired loans with a valuation allowance, Related Allowance	570	576
Impaired loans with a valuation allowance, Average Recorded Investment	1,149	2,606
Impaired loans with a valuation allowance, Interest Income Recognized	12	61
Construction and Land Development [Member]
Impaired loans without a valuation allowance, Recorded Investment	471	244
Impaired loans without a valuation allowance, Unpaid Principal Balance	498	251
Impaired loans without a valuation allowance, Related Allowance	0	0
Impaired loans without a valuation allowance, Average Recorded Investment	357	358
Impaired loans without a valuation allowance, Interest Income Recognized	4	19
Impaired loans with a valuation allowance, Recorded Investment	478	706
Impaired loans with a valuation allowance, Unpaid Principal Balance	478	706
Impaired loans with a valuation allowance, Related Allowance	460	460
Impaired loans with a valuation allowance, Average Recorded Investment	592	642
Impaired loans with a valuation allowance, Interest Income Recognized	4	49
Commercial and Industrial Loans [Member]
Impaired loans without a valuation allowance, Recorded Investment	2,045	2,111
Impaired loans without a valuation allowance, Unpaid Principal Balance	2,102	2,155
Impaired loans without a valuation allowance, Related Allowance	0	0
Impaired loans without a valuation allowance, Average Recorded Investment	2,078	2,277
Impaired loans without a valuation allowance, Interest Income Recognized	9	55
Impaired loans with a valuation allowance, Recorded Investment	744	1,049
Impaired loans with a valuation allowance, Unpaid Principal Balance	744	1,049
Impaired loans with a valuation allowance, Related Allowance	476	780
Impaired loans with a valuation allowance, Average Recorded Investment	896	700
Impaired loans with a valuation allowance, Interest Income Recognized	20	132
Consumer and Other Loans [Member]
Impaired loans without a valuation allowance, Recorded Investment	0	0
Impaired loans without a valuation allowance, Unpaid Principal Balance	0	0
Impaired loans without a valuation allowance, Related Allowance	0	0
Impaired loans without a valuation allowance, Average Recorded Investment	0	0
Impaired loans without a valuation allowance, Interest Income Recognized	0	0
Impaired loans with a valuation allowance, Recorded Investment	0	0
Impaired loans with a valuation allowance, Unpaid Principal Balance	0	0
Impaired loans with a valuation allowance, Related Allowance	0	0
Impaired loans with a valuation allowance, Average Recorded Investment	0	0
Impaired loans with a valuation allowance, Interest Income Recognized	$ 0	$ 0