Loans - Summary of Credit Quality Indicate Financial Receivable (Covered Loan 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
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	313,589	390,237	417,649
Covered Loans [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,328	1,702	1,761
Covered Loans [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	53,910	66,963	71,049
Covered Loans [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	21,147	23,055	20,876
Covered Loans [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	141,998	157,438	163,737
Covered Loans [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	25,333	35,424	40,990
Covered Loans [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	69,873	105,655	119,236
Covered Loans [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	22,545	26,550	27,768
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,302	2,184	2,697
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	145	134	135
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,687	7,508	7,609
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4,827	5,125	1,485
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,584	11,599	15,842
Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
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
Covered Loans [Member] | Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	27,756	43,179	50,702
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2	16	22
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,380	8,549	11,347
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	547	1,085	1,080
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	11,725	9,611	7,360
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,006	2,006	5,505
Covered Loans [Member] | Real Estate - Construction and Development [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,096	21,912	25,388
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
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
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	180,566	224,451	237,086
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	795	1,048	1,098
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	33,200	34,674	34,252
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	14,640	17,037	16,708
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	89,201	101,657	108,886
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,808	21,297	24,790
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	33,922	48,738	51,352
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
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
Covered Loans [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	82,445	95,173	101,146
Covered Loans [Member] | Real Estate - Residential [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Real Estate - Residential [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	531	638	641
Covered Loans [Member] | Real Estate - Residential [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	15,957	21,363	22,545
Covered Loans [Member] | Real Estate - Residential [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,815	4,748	2,902
Covered Loans [Member] | Real Estate - Residential [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	35,344	38,427	39,632
Covered Loans [Member] | Real Estate - Residential [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,649	6,979	9,196
Covered Loans [Member] | Real Estate - Residential [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	16,149	23,018	26,230
Covered Loans [Member] | Real Estate - Residential [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
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
Covered Loans [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	277	884	947
Covered Loans [Member] | Consumer Installment Loans [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Consumer Installment Loans [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Consumer Installment Loans [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	71	193	208
Covered Loans [Member] | Consumer Installment Loans [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	51	51
Covered Loans [Member] | Consumer Installment Loans [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	41	235	250
Covered Loans [Member] | Consumer Installment Loans [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	43	17	14
Covered Loans [Member] | Consumer Installment Loans [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	122	388	424
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
Covered Loans [Member] | Consumer Installment Loans [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0	0
Covered Loans [Member] | Other [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 0	$ 0	$ 0