Trust Preferred Capital Notes, Debt Items (Details) (USD $)								9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2013 MidCarolina I [Member]	Jul. 01, 2011 MidCarolina I [Member]	Sep. 30, 2013 MidCarolina II [Member]	Jul. 01, 2011 MidCarolina II [Member]	Jul. 01, 2011 MidCarolina Trust [Member]	Sep. 30, 2013 Junior Subordinated Debt Securities [Member]	Dec. 31, 2012 Junior Subordinated Debt Securities [Member]	Sep. 30, 2013 Junior Subordinated Debt Securities [Member] AMNB Trust I [Member]	Dec. 31, 2012 Junior Subordinated Debt Securities [Member] AMNB Trust I [Member]	Sep. 30, 2013 Junior Subordinated Debt Securities [Member] MidCarolina I [Member]	Dec. 31, 2012 Junior Subordinated Debt Securities [Member] MidCarolina I [Member]	Sep. 30, 2013 Junior Subordinated Debt Securities [Member] MidCarolina II [Member]	Dec. 31, 2012 Junior Subordinated Debt Securities [Member] MidCarolina II [Member]
Debt Instrument [Line Items]
Date Issued								Apr. 07, 2006		Oct. 29, 2002		Dec. 03, 2003
Interest Rate								Libor plus 1.35%		Libor plus 3.45%		Libor plus 2.95%
Variable Rate Basis								Libor plus		Libor plus		Libor plus
Basis Spread on Variable Rate (in hundredths)								1.35%		3.45%		2.95%
Maturity Date								Jun. 30, 2036		Nov. 07, 2032		Oct. 07, 2033
Principal Amount					$ 8,764,000	$ 27,394,000	$ 27,317,000	$ 20,619,000	$ 20,619,000	$ 4,084,000	$ 4,042,000	$ 2,691,000	$ 2,656,000
Valuation allowance associated with junior subordinated debenture	$ 1,071,000	$ 1,197,000	$ 918,000	$ 1,021,000