Loans - Summary of Covered Past Due Financial Receivables (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 2,171,600	$ 1,889,881	$ 1,770,059
Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	54,800		8,400
Commercial, Financial & Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	373,202	319,654	304,588
Real Estate - Construction & Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	205,019	161,507	149,346
Real Estate - Commercial & Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	1,010,195	907,524	850,000
Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	537,201	456,106	422,731
Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	30,080	30,782	31,902
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	21,480	33,383	42,315
Current Loans	188,118	237,896	288,935
Total Loans	209,598	271,279	331,250
Loans 90 Days or More Past Due and Still Accruing	143	714
Covered Loans [Member] | Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	3,918	8,534	9,456
Covered Loans [Member] | Loans 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	1,279	2,810	1,804
Covered Loans [Member] | Loans 90 or More Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	16,283	22,039	31,055
Covered Loans [Member] | Commercial, Financial & Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	2,147	2,465	7,392
Current Loans	15,519	19,002	17,817
Total Loans	17,666	21,467	25,209
Covered Loans [Member] | Commercial, Financial & Agricultural [Member] | Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	237	451	16
Covered Loans [Member] | Commercial, Financial & Agricultural [Member] | Loans 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	240	136	467
Covered Loans [Member] | Commercial, Financial & Agricultural [Member] | Loans 90 or More Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	1,670	1,878	6,909
Covered Loans [Member] | Real Estate - Construction & Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	3,368	7,167	8,718
Current Loans	11,634	16,280	22,882
Total Loans	15,002	23,447	31,600
Loans 90 Days or More Past Due and Still Accruing	143
Covered Loans [Member] | Real Estate - Construction & Development [Member] | Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	292	238	551
Covered Loans [Member] | Real Estate - Construction & Development [Member] | Loans 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	31	226	459
Covered Loans [Member] | Real Estate - Construction & Development [Member] | Loans 90 or More Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	3,045	6,703	7,708
Covered Loans [Member] | Real Estate - Commercial & Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	10,176	13,568	16,981
Current Loans	101,596	134,059	171,662
Total Loans	111,772	147,627	188,643
Loans 90 Days or More Past Due and Still Accruing		714
Covered Loans [Member] | Real Estate - Commercial & Farmland [Member] | Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	699	4,371	6,399
Covered Loans [Member] | Real Estate - Commercial & Farmland [Member] | Loans 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	81	1,486	139
Covered Loans [Member] | Real Estate - Commercial & Farmland [Member] | Loans 90 or More Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	9,396	7,711	10,443
Covered Loans [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	5,739	10,082	9,119
Current Loans	59,243	68,438	76,399
Total Loans	64,982	78,520	85,518
Covered Loans [Member] | Real Estate - Residential [Member] | Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	2,690	3,464	2,490
Covered Loans [Member] | Real Estate - Residential [Member] | Loans 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	927	962	690
Covered Loans [Member] | Real Estate - Residential [Member] | Loans 90 or More Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	2,122	5,656	5,939
Covered Loans [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	50	101	105
Current Loans	126	117	175
Total Loans	176	218	280
Covered Loans [Member] | Consumer Installment Loans [Member] | Loans 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due		10
Covered Loans [Member] | Consumer Installment Loans [Member] | Loans 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due			49
Covered Loans [Member] | Consumer Installment Loans [Member] | Loans 90 or More Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Past Due	$ 50	$ 91	$ 56