Trust Preferred Capital Notes (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013 Period	Dec. 31, 2006
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Proceeds from issuance of common securities	$ 619,000
AMNB Statutory Trust I [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	619,000
MidCarolina Trust [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	264,000
Trust Preferred Securities [Member]
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Proceeds from issuance of trust preferred securities		$ 20,000,000
Maturity Date	Sep. 30, 2036
Fixed interest rate of trust preferred securities (in hundredths)	6.66%
Reference rate, trust preferred securities	three-month LIBOR
Trust preferred securities, basis spread on variable rate (in hundredths)	1.35%
Number of consecutive quarterly periods for deferral of distributions on trust preferred securities, Maximum	20