Loans - Summary of Credit Quality Indicate Financial Receivable (Non-Covered Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 1,589,267	$ 1,450,635	$ 1,439,862
Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,589,267	1,450,635	1,439,862
Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	72,759	32,993	34,809
Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	230,810	236,500	244,466
Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	731,154	641,950	592,283
Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	30,729	31,433	30,176
Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	433,358	399,210	427,598
Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	28,952	35,298	35,478
Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	61,270	72,994	74,606
Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	235	257	446
Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	244,991	174,217	189,374
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	244,991	174,217	189,374
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	65,033	24,623	26,291
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,668	11,316	11,816
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	89,216	79,522	80,681
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	97	42	5
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	60,407	49,071	62,377
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,019	2,343	1,508
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	6,326	7,200	6,436
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	225	100	260
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	132,277	114,199	125,315
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	132,277	114,199	125,315
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,080	4,373	4,532
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	37,765	31,413	33,603
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,085	8,521	7,667
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	72,942	52,577	59,013
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,264	3,394	7,948
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,141	13,765	12,396
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade		156	156
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	799,149	732,322	713,240
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	799,149	732,322	713,240
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	278	309	220
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	147,355	147,966	152,678
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	421,669	351,997	324,270
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,054	9,012	8,773
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	183,371	176,395	184,146
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	12,089	19,401	14,742
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	24,333	27,242	28,411
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	355,920	346,480	343,332
Real Estate - Residential [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	355,920	346,480	343,332
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	420	464	411
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	56,464	71,254	74,040
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	142,186	114,418	105,531
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	13,275	13,788	13,650
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	109,604	113,591	113,560
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	11,427	9,672	10,535
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	22,534	23,292	25,583
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10	1	22
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	36,303	40,178	43,441
Consumer Installment Loans [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	36,303	40,178	43,441
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,028	7,597	7,887
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,243	1,591	1,400
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	19,691	21,361	23,038
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	218	70	81
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,034	7,576	8,502
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	153	488	745
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	936	1,495	1,780
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			8
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,627	43,239	25,160
Other [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,627	43,239	25,160
Other [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	20,627	43,239	25,160
Other [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade