Loans - Summary of Non-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
Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	334,783	244,373	244,991
Real Estate - Construction and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	154,315	146,371	132,277
Real Estate - Commercial and Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	882,160	808,323	799,149
Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	436,515	366,882	355,920
Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	31,403	34,249	36,303
Purchased Non-Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	8,001	12,903
Loans 60-89 Days Past Due	2,853	3,314
Loans 90 or More Days Past Due	17,395	5,289
Total Loans Past Due	28,249	21,506
Current Loans	645,475	427,247
Total Loans	673,724	448,753
Loans 90 Days or More Past Due and Still Accruing	1,358	0
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	33	370
Loans 60-89 Days Past Due	46	70
Loans 90 or More Days Past Due	55	11
Total Loans Past Due	134	451
Current Loans	37,943	31,690
Total Loans	38,077	32,141
Loans 90 Days or More Past Due and Still Accruing	0	0
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	520	1,008
Loans 60-89 Days Past Due	135	89
Loans 90 or More Days Past Due	3,069	325
Total Loans Past Due	3,724	1,422
Current Loans	56,538	29,754
Total Loans	60,262	31,176
Loans 90 Days or More Past Due and Still Accruing	1,100	0
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	3,497	6,851
Loans 60-89 Days Past Due	1,227	2,064
Loans 90 or More Days Past Due	8,266	1,516
Total Loans Past Due	12,990	10,431
Current Loans	283,800	169,467
Total Loans	296,790	179,898
Loans 90 Days or More Past Due and Still Accruing	258	0
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	3,915	4,667
Loans 60-89 Days Past Due	1,440	1,074
Loans 90 or More Days Past Due	5,929	3,428
Total Loans Past Due	11,284	9,169
Current Loans	262,063	191,682
Total Loans	273,347	200,851
Loans 90 Days or More Past Due and Still Accruing	0	0
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-59 Days Past Due	36	7
Loans 60-89 Days Past Due	5	17
Loans 90 or More Days Past Due	76	9
Total Loans Past Due	117	33
Current Loans	5,131	4,654
Total Loans	5,248	4,687
Loans 90 Days or More Past Due and Still Accruing	$ 0	$ 0