Loans - Summary of Excluding Purchased Non-Covered and Covered Past Due Financial Receivables (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	$ 8,000		$ 17,000
Total Loans	1,848,759	1,618,454	1,589,267
Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	9,277	21,890	11,718
Loans 60-89 Days Past Due	3,367	3,661	7,335
Loans 90 or More Days Past Due	21,999	27,659	30,004
Total Loans Past Due	34,643	53,210	49,057
Current Loans	1,814,116	1,565,244	1,540,210
Total Loans	1,848,759	1,618,454	1,589,267
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	334,783	244,373	244,991
Commercial, Financial and Agricultural [Member] | Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	271	10,893	623
Loans 60-89 Days Past Due	400	272	297
Loans 90 or More Days Past Due	2,483	4,081	4,107
Total Loans Past Due	3,154	15,246	5,027
Current Loans	331,629	229,127	239,964
Total Loans	334,783	244,373	244,991
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Real Estate - Construction and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	154,315	146,371	132,277
Real Estate - Construction and Development [Member] | Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	1,232	1,026	1,200
Loans 60-89 Days Past Due	285	69	794
Loans 90 or More Days Past Due	2,899	3,935	4,229
Total Loans Past Due	4,416	5,030	6,223
Current Loans	149,899	141,341	126,054
Total Loans	154,315	146,371	132,277
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Real Estate - Commercial and Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	882,160	808,323	799,149
Real Estate - Commercial and Farmland [Member] | Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	3,025	3,981	3,883
Loans 60-89 Days Past Due	484	1,388	2,458
Loans 90 or More Days Past Due	8,918	7,751	9,523
Total Loans Past Due	12,427	13,120	15,864
Current Loans	869,733	795,203	783,285
Total Loans	882,160	808,323	799,149
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	436,515	366,882	355,920
Real Estate - Residential [Member] | Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	4,416	5,422	5,515
Loans 60-89 Days Past Due	2,085	1,735	3,531
Loans 90 or More Days Past Due	7,303	11,587	11,818
Total Loans Past Due	13,804	18,744	20,864
Current Loans	422,711	348,138	335,056
Total Loans	436,515	366,882	355,920
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	31,403	34,249	36,303
Consumer Installment Loans [Member] | Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	333	568	497
Loans 60-89 Days Past Due	113	197	255
Loans 90 or More Days Past Due	396	305	327
Total Loans Past Due	842	1,070	1,079
Current Loans	30,561	33,179	35,224
Total Loans	31,403	34,249	36,303
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	9,583	18,256	20,627
Other [Member] | Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	0	0	0
Loans 60-89 Days Past Due	0	0	0
Loans 90 or More Days Past Due	0	0	0
Total Loans Past Due	0	0	0
Current Loans	9,583	18,256	20,627
Total Loans	9,583	18,256	20,627
Loans 90 Days or More Past Due and Still Accruing	$ 0	$ 0	$ 0