Credit Quality of Loans and Allowance for Loan Losses (Details 4) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Nonaccrual loans
Nonaccrual loans	$ 18,025	$ 15,973
Real Estate Construction and Land Development [Member]
Nonaccrual loans
Nonaccrual loans	4,508	6,795
Real Estate Secured by Farmland [Member]
Nonaccrual loans
Nonaccrual loans	358
Real Estate Secured by Residential Properties [Member]
Nonaccrual loans
Nonaccrual loans	2,579	2,113
Real Estate Secured by Nonfarm Nonresidential [Member]
Nonaccrual loans
Nonaccrual loans	10,364	6,767
Consumer Installment [Member]
Nonaccrual loans
Nonaccrual loans	44	22
Credit Cards and Related Plans [Member]
Nonaccrual loans
Nonaccrual loans
Commercial and Industrial [Member]
Nonaccrual loans
Nonaccrual loans	172	276
Loans to Finance Agricultural Production [Member]
Nonaccrual loans
Nonaccrual loans
All Other Loans [Member]
Nonaccrual loans
Nonaccrual loans