Loans - Summary of Non-Covered Past Due Financial Receivables (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 2,171,600	$ 1,889,881	$ 1,770,059
Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	54,800		8,400
Commercial, Financial & Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	373,202	319,654	304,588
Real Estate - Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	205,019	161,507	149,346
Real Estate - Commercial & Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,010,195	907,524	850,000
Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	537,201	456,106	422,731
Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	30,080	30,782	31,902
Purchased Non-Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	25,182	32,022	27,044
Current Loans	783,131	642,217	675,087
Total Loans	808,313	674,239	702,131
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Purchased Non-Covered Loans [Member] | Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6,214	10,347	9,087
Purchased Non-Covered Loans [Member] | Loans 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,225	4,420	2,811
Purchased Non-Covered Loans [Member] | Loans 90 or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	15,743	17,255	15,146
Purchased Non-Covered Loans [Member] | Commercial, Financial & Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,303	726	306
Current Loans	44,034	37,315	41,277
Total Loans	45,337	38,041	41,583
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Purchased Non-Covered Loans [Member] | Commercial, Financial & Agricultural [Member] | Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due		461	137
Purchased Non-Covered Loans [Member] | Commercial, Financial & Agricultural [Member] | Loans 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,101	90	26
Purchased Non-Covered Loans [Member] | Commercial, Financial & Agricultural [Member] | Loans 90 or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	202	175	143
Purchased Non-Covered Loans [Member] | Real Estate - Construction & Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,271	3,642	3,045
Current Loans	74,031	54,720	61,039
Total Loans	75,302	58,362	64,084
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Purchased Non-Covered Loans [Member] | Real Estate - Construction & Development [Member] | Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	245	790	712
Purchased Non-Covered Loans [Member] | Real Estate - Construction & Development [Member] | Loans 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due		1,735	168
Purchased Non-Covered Loans [Member] | Real Estate - Construction & Development [Member] | Loans 90 or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,026	1,117	2,165
Purchased Non-Covered Loans [Member] | Real Estate - Commercial & Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	11,901	12,830	9,515
Current Loans	392,687	293,876	302,233
Total Loans	404,588	306,706	311,748
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Purchased Non-Covered Loans [Member] | Real Estate - Commercial & Farmland [Member] | Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	2,115	2,107	1,263
Purchased Non-Covered Loans [Member] | Real Estate - Commercial & Farmland [Member] | Loans 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	724	1,194	1,605
Purchased Non-Covered Loans [Member] | Real Estate - Commercial & Farmland [Member] | Loans 90 or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	9,062	9,529	6,647
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	10,617	14,677	14,079
Current Loans	266,181	251,665	264,372
Total Loans	276,798	266,342	278,451
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	3,848	6,907	6,952
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | Loans 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	1,400	1,401	983
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | Loans 90 or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	5,369	6,369	6,144
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	90	147	99
Current Loans	6,198	4,641	6,166
Total Loans	6,288	4,788	6,265
Loans 90 Days or More Past Due and Still Accruing	0	0	0
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | Loans 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	6	82	23
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | Loans 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due			29
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | Loans 90 or More Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Past Due	$ 84	$ 65	$ 47