Loans - Summary of Non-Covered Past Due Financial Receivables (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	$ 17,000		$ 23,500
Total Loans	1,589,267	1,450,635	1,439,862
Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	11,718	11,825	13,104
Loans 60-89 Days Past Due	7,335	6,097	4,233
Loans 90 or More Days Past Due	30,004	34,287	36,733
Total Loans Past Due	49,057	52,209	54,070
Current Loans	1,540,210	1,398,426	1,385,792
Total Loans	1,589,267	1,450,635	1,439,862
Loans 90 Days or More Past Due and Still Accruing
Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	244,991	174,217	189,374
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	623	258	1,192
Loans 60-89 Days Past Due	297	312	639
Loans 90 or More Days Past Due	4,107	3,969	3,786
Total Loans Past Due	5,027	4,539	5,617
Current Loans	239,964	169,678	183,757
Total Loans	244,991	174,217	189,374
Loans 90 Days or More Past Due and Still Accruing
Real Estate - Construction and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	132,277	114,199	125,315
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	1,200	347	518
Loans 60-89 Days Past Due	794	332	152
Loans 90 or More Days Past Due	4,229	8,969	8,180
Total Loans Past Due	6,223	9,648	8,850
Current Loans	126,054	104,551	116,465
Total Loans	132,277	114,199	125,315
Loans 90 Days or More Past Due and Still Accruing
Real Estate - Commercial and Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	799,149	732,322	713,240
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	3,883	2,867	3,507
Loans 60-89 Days Past Due	2,458	2,296	812
Loans 90 or More Days Past Due	9,523	9,544	11,402
Total Loans Past Due	15,864	14,707	15,721
Current Loans	783,285	717,615	697,519
Total Loans	799,149	732,322	713,240
Loans 90 Days or More Past Due and Still Accruing
Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	355,920	346,480	343,332
Real Estate - Residential [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	5,515	7,651	7,200
Loans 60-89 Days Past Due	3,531	2,766	2,346
Loans 90 or More Days Past Due	11,818	10,990	12,372
Total Loans Past Due	20,864	21,407	21,918
Current Loans	335,056	325,073	321,414
Total Loans	355,920	346,480	343,332
Loans 90 Days or More Past Due and Still Accruing
Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	36,303	40,178	43,441
Consumer Installment Loans [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	497	702	687
Loans 60-89 Days Past Due	255	391	284
Loans 90 or More Days Past Due	327	815	993
Total Loans Past Due	1,079	1,908	1,964
Current Loans	35,224	38,270	41,477
Total Loans	36,303	40,178	43,441
Loans 90 Days or More Past Due and Still Accruing
Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	20,627	43,239	25,160
Other [Member] | Non-Covered Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	20,627	43,239	25,160
Total Loans	20,627	43,239	25,160
Loans 90 Days or More Past Due and Still Accruing