Loans - Summary of Credit Quality Indicate Financial Receivable (Loan Excluding Purchased Non-Covered and Covered Loans Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 1,848,759	$ 1,618,454	$ 1,589,267
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	334,783	244,373	244,991
Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	154,315	146,371	132,277
Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	882,160	808,323	799,149
Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	436,515	366,882	355,920
Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	31,403	34,249	36,303
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,583	18,256	20,627
Excluding Purchased Non-Covered and Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,848,759	1,618,454	1,589,267
Excluding Purchased Non-Covered and Covered Loans [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	121,486	74,381	72,759
Excluding Purchased Non-Covered and Covered Loans [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	222,714	230,212	230,810
Excluding Purchased Non-Covered and Covered Loans [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	908,055	773,051	731,154
Excluding Purchased Non-Covered and Covered Loans [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	28,826	31,604	30,729
Excluding Purchased Non-Covered and Covered Loans [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	484,199	420,491	433,358
Excluding Purchased Non-Covered and Covered Loans [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	31,750	30,591	28,952
Excluding Purchased Non-Covered and Covered Loans [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	51,640	57,987	61,270
Excluding Purchased Non-Covered and Covered Loans [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	88	137	235
Excluding Purchased Non-Covered and Covered Loans [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	334,783	244,373	244,991
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	114,298	66,983	65,033
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	29,665	24,789	20,668
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	110,337	93,852	89,216
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	186	127	97
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	73,251	50,373	60,407
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,438	2,111	3,019
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,608	6,011	6,326
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	127	225
Excluding Purchased Non-Covered and Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	154,315	146,371	132,277
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	171	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4,114	4,655	5,080
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	50,427	45,195	37,765
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,292	8,343	7,085
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	83,245	78,736	72,942
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,781	2,876	2,264
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,285	6,566	7,141
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Construction and Development [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	882,160	808,323	799,149
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	251	265	278
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	136,303	147,157	147,355
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	478,551	431,790	421,669
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,574	10,219	10,054
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	217,226	181,645	183,371
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	16,217	11,849	12,089
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	23,950	25,398	24,333
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	88	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	436,515	366,882	355,920
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	479	419	420
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	51,508	52,335	56,464
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	241,457	165,339	142,186
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,469	12,641	13,275
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	105,635	103,427	109,604
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,060	13,558	11,427
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	17,907	19,153	22,534
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	10	10
Excluding Purchased Non-Covered and Covered Loans [Member] | Real Estate - Residential [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	31,403	34,249	36,303
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	6,287	6,714	7,028
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,124	1,276	1,243
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	17,700	18,619	19,691
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	305	274	218
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4,842	6,310	7,034
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	254	197	153
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	890	859	936
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Consumer Installment Loans [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,583	18,256	20,627
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,583	18,256	20,627
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Excluding Purchased Non-Covered and Covered Loans [Member] | Other [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 0	$ 0	$ 0