Loans - Summary of Non-Covered Past Due Financial Receivables (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	$ 20,700	$ 40,300
Total Loans	1,555,827	1,450,635	1,365,489
Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	13,646	11,825	14,009
Loans 60-89 Days Past Due	7,617	6,097	13,856
Loans 90 or More Days Past Due	27,057	34,287	36,722
Total Loans Past Due	48,320	52,209	64,587
Current Loans	1,507,507	1,398,426	1,300,902
Total Loans	1,555,827	1,450,635	1,365,489
Loans 90 Days or More Past Due and Still Accruing			1
Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	208,424	174,217	174,903
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	1,449	258	531
Loans 60-89 Days Past Due	502	312	701
Loans 90 or More Days Past Due	4,013	3,969	4,371
Total Loans Past Due	5,964	4,539	5,603
Current Loans	202,460	169,678	169,300
Total Loans	208,424	174,217	174,903
Real Estate - Construction and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	134,607	114,199	124,556
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	1,638	347	1,986
Loans 60-89 Days Past Due	104	332	2,119
Loans 90 or More Days Past Due	5,418	8,969	7,855
Total Loans Past Due	7,160	9,648	11,960
Current Loans	127,447	104,551	112,596
Total Loans	134,607	114,199	124,556
Real Estate - Commercial and Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	788,654	732,322	675,404
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	5,392	2,867	5,282
Loans 60-89 Days Past Due	1,580	2,296	6,930
Loans 90 or More Days Past Due	5,333	9,544	8,597
Total Loans Past Due	12,305	14,707	20,809
Current Loans	776,349	717,615	654,595
Total Loans	788,654	732,322	675,404
Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	357,685	346,480	332,124
Real Estate - Residential [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	4,735	7,651	5,665
Loans 60-89 Days Past Due	5,256	2,766	3,885
Loans 90 or More Days Past Due	11,745	10,990	14,782
Total Loans Past Due	21,736	21,407	24,332
Current Loans	335,949	325,073	307,792
Total Loans	357,685	346,480	332,124
Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	36,923	40,178	41,431
Consumer Installment Loans [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	432	702	545
Loans 60-89 Days Past Due	175	391	221
Loans 90 or More Days Past Due	548	815	1,117
Total Loans Past Due	1,155	1,908	1,883
Current Loans	35,768	38,270	39,548
Total Loans	36,923	40,178	41,431
Loans 90 Days or More Past Due and Still Accruing			1
Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	29,534	43,239	17,071
Other [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	29,534	43,239	17,071
Total Loans	$ 29,534	$ 43,239	$ 17,071