Loans - Summary of Credit Quality Indicate Financial Receivable (Non-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
Purchased Non-Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	673,724	448,753
Purchased Non-Covered Loans [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,965	2,605
Purchased Non-Covered Loans [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	35,461	34,474
Purchased Non-Covered Loans [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	180,702	88,893
Purchased Non-Covered Loans [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,216	0
Purchased Non-Covered Loans [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	399,729	274,442
Purchased Non-Covered Loans [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,048	22,962
Purchased Non-Covered Loans [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	32,565	25,377
Purchased Non-Covered Loans [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	38	0
Purchased Non-Covered Loans [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	38,077	32,141
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,187	1,865
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,023	4,606
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	11,230	5,172
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8	0
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	16,467	19,638
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,494	576
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	668	284
Purchased Non-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
Purchased Non-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
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	60,262	31,176
Purchased Non-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
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	447	7
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	12,345	3,960
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	38,426	20,733
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,164	1,760
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	6,880	4,716
Purchased Non-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
Purchased Non-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
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	296,790	179,898
Purchased Non-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
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	14,136	12,998
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	90,915	43,802
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	167,458	102,260
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,300	9,554
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	14,981	11,284
Purchased Non-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
Purchased Non-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
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	273,347	200,851
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	292	289
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	15,336	16,160
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	64,178	34,576
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,208	0
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	175,313	129,923
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,071	10,878
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,915	9,025
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	34	0
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,248	4,687
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	486	451
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	519	703
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,034	1,383
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,065	1,888
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	19	194
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	121	68
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4	0
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0	0
Purchased Non-Covered Loans [Member] | Other [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 0	$ 0