Borrowings (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Borrowings [Abstract]
Remaining credit availability	$ 76,000,000
Federal Home Loan Bank advances outstanding	77,912,000	82,912,000
Federal Home Loan Bank advances, Interest rate, range from (in hundredths)	0.14%
Federal Home Loan Bank advances, Interest rate, range to (in hundredths)	1.98%
Federal Home Loan Bank advances, Weighted-average rate (in hundredths)	1.17%	1.14%
Future maturities of long-term debt [Abstract]
Due in 2013	17,912,000
Due in 2014	40,000,000
Due in 2015	15,000,000
Due in 2016	5,000,000
Total	77,912,000
Federal Funds Purchased [Abstract]
Federal Funds Purchased Amount	0	0	0
Weighted-average interest rate at year-end (in hundredths)	0.00%	0.00%	0.00%
Maximum amount outstanding at any month's end	0	0	5,000,000
Average amount outstanding during the year	1,000	42,000	25,000
Weighted-average interest rate during the year (in hundredths)	0.25%	0.25%	0.00%
Securities Sold Under Agreements to Repurchase [Abstract]
Securities Sold Under Agreements to Repurchase Amount	33,975,000	31,686,000	25,562,000
Weighted-average interest rate at year-end (in hundredths)	0.90%	1.04%	0.94%
Maximum amount outstanding at any month's end	38,949,000	36,617,000	27,542,000
Average amount outstanding during the year	34,177,000	33,162,000	25,314,000
Weighted-average interest rate during the year (in hundredths)	0.97%	0.88%	0.81%
Short-term Borrowings [Abstract]
Short-term Borrowings	11,873,000	28,331,000	13,320,000
Weighted-average interest rate at year-end (in hundredths)	5.00%	5.00%	5.13%
Maximum amount outstanding at any month's end	17,656,000	28,331,000	21,875,000
Average amount outstanding during the year	8,725,000	9,555,000	10,419,000
Weighted-average interest rate during the year (in hundredths)	4.49%	3.33%	3.77%
Federal Reserve Bank of Richmond [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum credit limit	48,900,000
Revolving lines of credit, outstanding balance	0
Other Institutions [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum credit limit	24,000,000
Southern Trust Mortgage [Member]
Line of Credit Facility [Line Items]
Loan guarantees by Middleburg Bank	10,000,000
Southern Trust Mortgage [Member] | Regional Bank [Member]
Line of Credit Facility [Line Items]
Revolving lines of credit, outstanding balance	11,900,000
Southern Trust Mortgage [Member] | Regional Bank [Member] | Fund Mortgage Held For Sale [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum credit limit	24,000,000
Weighted-average interest rate (in hundredths)	5.00%
Southern Trust Mortgage [Member] | Middleburg Bank [Member] | Fund Mortgage Held For Sale [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum credit limit	70,000,000
Revolving lines of credit, outstanding balance	69,200,000
Southern Trust Mortgage [Member] | Middleburg Bank [Member] | Operating Purpose [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum credit limit	5,000,000
Revolving lines of credit, outstanding balance	$ 1,200,000