Allowance for Loan Losses (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Financing Receivable Allowance For Credit Losses [Line Items]
Provision of loan losses	$ (188,000)	$ 792,000
Decrease percentage non accrual loans to total loans (in hundredths)	2.84%	3.26%
Reserve ratio decrease percentage of portfolio loans (in hundredths)	1.89%		2.02%
Allowance for loan losses [Roll Forward]
Beginning Balance	14,311,000	14,623,000	14,623,000
Charge-offs	(719,000)		(4,271,000)
Recoveries	104,000		521,000
Provision	(188,000)		3,438,000
Ending Balance	13,508,000		14,311,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	4,304,000		4,303,000
Collectively evaluated for impairment	9,204,000		10,008,000
Total ending allowance balances	13,508,000		14,311,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	25,363,000		26,795,000
Collectively Evaluated for Impairment	689,223,000		682,682,000
Total ending loan balances	714,586,000		709,477,000
Real Estate Construction [Member]
Allowance for loan losses [Roll Forward]
Beginning Balance	1,258,000	897,000	897,000
Charge-offs	(87,000)		(2,152,000)
Recoveries	37,000		2,000
Provision	32,000		2,511,000
Ending Balance	1,240,000		1,258,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	484,000		166,000
Collectively evaluated for impairment	756,000		1,092,000
Total ending allowance balances	1,240,000		1,258,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	2,896,000		2,969,000
Collectively Evaluated for Impairment	43,193,000		47,249,000
Total ending loan balances	46,089,000		50,218,000
Real Estate Loans Secured by Farmland [Member]
Allowance for loan losses [Roll Forward]
Beginning Balance	135,000	110,000	110,000
Charge-offs	0		0
Recoveries	0		0
Provision	(10,000)		25,000
Ending Balance	125,000		135,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	125,000		135,000
Total ending allowance balances	125,000		135,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	0		0
Collectively Evaluated for Impairment	11,805,000		11,876,000
Total ending loan balances	11,805,000		11,876,000
Real Estate Secured by 1 - 4 Family Residential [Member]
Allowance for loan losses [Roll Forward]
Beginning Balance	6,276,000	7,465,000	7,465,000
Charge-offs	(489,000)		(893,000)
Recoveries	50,000		388,000
Provision	(29,000)		(684,000)
Ending Balance	5,808,000		6,276,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	2,035,000		2,724,000
Collectively evaluated for impairment	3,773,000		3,552,000
Total ending allowance balances	5,808,000		6,276,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	10,177,000		10,792,000
Collectively Evaluated for Impairment	258,593,000		249,828,000
Total ending loan balances	268,770,000		260,620,000
Other Real Estate Loans [Member]
Allowance for loan losses [Roll Forward]
Beginning Balance	4,348,000	4,385,000	4,385,000
Charge-offs	(97,000)		(760,000)
Recoveries	9,000		86,000
Provision	(161,000)		637,000
Ending Balance	4,099,000		4,348,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	964,000		1,045,000
Collectively evaluated for impairment	3,135,000		3,303,000
Total ending allowance balances	4,099,000		4,348,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	9,424,000		10,640,000
Collectively Evaluated for Impairment	249,979,000		244,290,000
Total ending loan balances	259,403,000		254,930,000
Commercial [Member]
Allowance for loan losses [Roll Forward]
Beginning Balance	2,098,000	1,621,000	1,621,000
Charge-offs	(38,000)		(394,000)
Recoveries	5,000		12,000
Provision	(18,000)		859,000
Ending Balance	2,047,000		2,098,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	791,000		338,000
Collectively evaluated for impairment	1,256,000		1,760,000
Total ending allowance balances	2,047,000		2,098,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	2,836,000		2,364,000
Collectively Evaluated for Impairment	113,185,000		116,209,000
Total ending loan balances	116,021,000		118,573,000
Consumer [Member]
Allowance for loan losses [Roll Forward]
Beginning Balance	196,000	145,000	145,000
Charge-offs	(8,000)		(72,000)
Recoveries	3,000		33,000
Provision	(2,000)		90,000
Ending Balance	189,000		196,000
Ending allowance balance attributable to loans [Abstract]
Individually evaluated for impairment	30,000		30,000
Collectively evaluated for impairment	159,000		166,000
Total ending allowance balances	189,000		196,000
Ending loan recorded investment balances [Abstract]
Individually Evaluated for Impairment	30,000		30,000
Collectively Evaluated for Impairment	12,468,000		13,230,000
Total ending loan balances	$ 12,498,000		$ 13,260,000