Loans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Dec. 11, 2015
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					$ 709,115,000	$ 695,031,000
Individually evaluated for impairment					12,604,000	12,284,000
Loans acquired with deteriorated credit quality					3,669,000	3,818,000
Collectively evaluated for impairment					692,842,000	678,929,000
Allowance for loan losses					7,359,000	7,106,000
Allowance for loan losses related to individually evaluated for impairment					587,000	355,000
Allowance for loan losses related to loans acquired with deteriorated credit quality					0	0
Allowance for loan losses related to collectively evaluated for impairment					6,772,000	6,751,000
Net loans					701,756,000	687,925,000
Net loans, individually evaluated for impairment					12,017,000	11,929,000
Net loans, loans acquired with deteriorated credit quality					3,669,000	3,818,000
Net loans, collectively evaluated for impairment					686,070,000	672,178,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					587,000	355,000
Collectively evaluated for impairment					6,772,000	6,751,000
Total	$ 7,359,000	$ 6,922,000	$ 7,359,000	$ 6,815,000	7,359,000	7,106,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	7,275,000	6,922,000	7,106,000	6,815,000
Charge-offs	(84,000)	(90,000)	(99,000)	(115,000)
Recoveries	33,000	7,000	82,000	19,000
Provision	135,000	120,000	270,000	240,000
Balance at end of period	7,359,000	6,959,000	$ 7,359,000	6,959,000
Minimum [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Number of days past for loan to be considered impaired, Minimum			90 days
First Mortgage [Member] | Minimum [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Period of mortgage on real estate			15 years
First Mortgage [Member] | Maximum [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Period of mortgage on real estate			30 years
Second Mortgage [Member] | Maximum [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Period of mortgage on real estate			15 years
Residential Real Estate Loans [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					203,980,000	203,407,000
Individually evaluated for impairment					518,000	304,000
Loans acquired with deteriorated credit quality					34,000	35,000
Collectively evaluated for impairment					203,428,000	203,068,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					46,000	37,000
Collectively evaluated for impairment					944,000	868,000
Total	990,000	923,000	$ 990,000	878,000	990,000	905,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	966,000	923,000	905,000	878,000
Charge-offs	(43,000)	(17,000)	(43,000)	(34,000)
Recoveries	0	0	0	0
Provision	67,000	25,000	128,000	87,000
Balance at end of period	990,000	931,000	990,000	931,000
Commercial and Agricultural Real Estate Loans [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					309,287,000	295,364,000
Individually evaluated for impairment					6,404,000	6,235,000
Loans acquired with deteriorated credit quality					2,753,000	2,908,000
Collectively evaluated for impairment					300,130,000	286,221,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					126,000	62,000
Collectively evaluated for impairment					3,793,000	3,723,000
Total	3,919,000	3,699,000	3,785,000	3,870,000	3,919,000	3,785,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	3,938,000	3,699,000	3,785,000	3,870,000
Charge-offs	0	(56,000)	0	(56,000)
Recoveries	4,000	3,000	8,000	7,000
Provision	(23,000)	33,000	126,000	(142,000)
Balance at end of period	3,919,000	3,679,000	3,919,000	3,679,000
Construction Real Estate Loans [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					10,481,000	15,011,000
Individually evaluated for impairment					0	0
Loans acquired with deteriorated credit quality					0	0
Collectively evaluated for impairment					10,481,000	15,011,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					0	0
Collectively evaluated for impairment					18,000	24,000
Total	18,000	11,000	24,000	26,000	18,000	24,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	14,000	11,000	24,000	26,000
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	4,000	3,000	(6,000)	(12,000)
Balance at end of period	18,000	14,000	18,000	14,000
Consumer [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					11,439,000	11,543,000
Individually evaluated for impairment					0	0
Loans acquired with deteriorated credit quality					6,000	9,000
Collectively evaluated for impairment					11,433,000	11,534,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					0	0
Collectively evaluated for impairment					104,000	102,000
Total	104,000	82,000	104,000	84,000	104,000	102,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	96,000	82,000	102,000	84,000
Charge-offs	(23,000)	(17,000)	(38,000)	(24,000)
Recoveries	29,000	4,000	68,000	12,000
Provision	2,000	20,000	(28,000)	17,000
Balance at end of period	104,000	89,000	104,000	89,000
Other Commercial and Agricultural Loans [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					74,089,000	71,206,000
Individually evaluated for impairment					5,682,000	5,745,000
Loans acquired with deteriorated credit quality					876,000	866,000
Collectively evaluated for impairment					67,531,000	64,595,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					415,000	256,000
Collectively evaluated for impairment					1,149,000	1,049,000
Total	1,564,000	1,286,000	1,564,000	1,224,000	1,564,000	1,305,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,347,000	1,286,000	1,305,000	1,224,000
Charge-offs	(18,000)	0	(18,000)	(1,000)
Recoveries	0	0	6,000	0
Provision	235,000	216,000	271,000	279,000
Balance at end of period	1,564,000	1,502,000	1,564,000	1,502,000
State and Political Subdivision Loans [Member]
Segments of loan portfolio and allowance for loan losses [Abstract]
Total financing receivables					99,839,000	98,500,000
Individually evaluated for impairment					0	0
Loans acquired with deteriorated credit quality					0	0
Collectively evaluated for impairment					99,839,000	98,500,000
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					0	0
Collectively evaluated for impairment					764,000	593,000
Total	764,000	572,000	764,000	545,000	764,000	593,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	666,000	572,000	593,000	545,000
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	98,000	(4,000)	171,000	23,000
Balance at end of period	764,000	568,000	764,000	568,000
Unallocated [Member]
Summary of allowance for loan losses into amount required for loans individually evaluated for impairment and the amount required for loans collectively evaluated for impairment [Abstract]
Individually evaluated for impairment					0	0
Collectively evaluated for impairment					0	392,000
Total	0	349,000	0	188,000	0	392,000
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	248,000	349,000	392,000	188,000
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(248,000)	(173,000)	(392,000)	(12,000)
Balance at end of period	0	$ 176,000	0	$ 176,000
First National Bank of Fredericksburg [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Unpaid principal balance amount							$ 6,969,000
Estimated fair value							3,809,000
Contractually required principal and interest at acquisition							9,913,000
Expected cash flows							4,474,000
Non-accretable discount							5,439,000
Accretable discount	551,000		637,000		464,000	637,000	$ 665,000
Changes in the accretable yield for purchased credit-impaired loans [Roll Forward]
Balance at beginning of period	551,000		637,000
Accretion	(87,000)		(173,000)
Balance at end of period	$ 464,000		$ 464,000
Loans acquired with specific evidence of deterioration in credit quality [Abstract]
Outstanding balance					6,616,000	6,950,000
Carrying amount					$ 3,669,000	$ 3,818,000