Loans and Leases - Age Analysis of Past Due Loans and Leases (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	$ 7,003	$ 9,963
60-89 Days Past Due	699	1,604
Greater Than 90 Days Past Due	441	365
Total Past Due	8,143	11,932
Current	1,428,130	1,392,374
Loans and Leases Held for Investment	1,481,862	1,446,406
Recorded Investment Greater than 90 Days Past Due and Accruing Interest	441	365
Commercial, financial and agricultural [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	416	3,741
60-89 Days Past Due	95	33
Total Past Due	511	3,774
Current	464,588	469,197
Loans and Leases Held for Investment	468,421	477,662
Real estate-commercial [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	1,173	2,212
60-89 Days Past Due		723
Total Past Due	1,173	2,935
Current	504,086	491,498
Loans and Leases Held for Investment	530,122	514,953
Real estate-construction [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	306
Total Past Due	306
Current	74,959	74,656
Loans and Leases Held for Investment	91,250	90,397
Real estate-residential secured for business purpose [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	1,663	340
Total Past Due	1,663	340
Current	33,344	32,026
Loans and Leases Held for Investment	35,179	32,481
Real estate-residential secured for personal purpose [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	1,617	1,783
60-89 Days Past Due	152
Total Past Due	1,769	1,783
Current	143,953	130,405
Loans and Leases Held for Investment	146,526	132,245
Real estate-home equity secured for personal purpose [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	276	298
60-89 Days Past Due	64	68
Greater Than 90 Days Past Due	54	117
Total Past Due	394	483
Current	82,333	79,968
Loans and Leases Held for Investment	82,727	80,478
Recorded Investment Greater than 90 Days Past Due and Accruing Interest	54	117
Loans to individuals [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	551	386
60-89 Days Past Due	115	236
Greater Than 90 Days Past Due	347	204
Total Past Due	1,013	826
Current	42,729	44,089
Loans and Leases Held for Investment	43,780	44,965
Recorded Investment Greater than 90 Days Past Due and Accruing Interest	347	204
Lease financings [Member]
Age Analysis of Past Due Loans and Leases
30-59 Days Past Due	1,001	1,203
60-89 Days Past Due	273	544
Greater Than 90 Days Past Due	40	44
Total Past Due	1,314	1,791
Current	82,138	70,535
Loans and Leases Held for Investment	83,857	73,225
Recorded Investment Greater than 90 Days Past Due and Accruing Interest	$ 40	$ 44