Loans - Summary of Credit Quality Indicate Financial Receivable (Non-Covered Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 1,555,827	$ 1,450,635	$ 1,365,489
Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,555,827	1,450,635	1,365,489
Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	44,852	32,993	28,282
Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	241,691	236,500	251,157
Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	708,605	641,950	540,562
Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	29,830	31,433	30,131
Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	443,104	399,210	397,984
Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	29,266	35,298	36,307
Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	57,879	72,994	80,824
Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	598	257	242
Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	208,424	174,217	174,903
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	208,424	174,217	174,903
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	37,173	24,623	20,395
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	17,783	11,316	11,909
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	82,636	79,522	79,985
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	108	42
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	60,981	49,071	54,072
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,154	2,343	1,404
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	5,991	7,200	7,137
Commercial, Financial and Agricultural [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	598	100	1
Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	134,607	114,199	124,556
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	134,607	114,199	124,556
Real Estate - Construction and Development [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			17
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	4,934	4,373	3,628
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	36,654	31,413	39,077
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	6,878	8,521	6,691
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	75,273	52,577	57,266
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	3,183	3,394	4,018
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	7,685	13,765	13,703
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 - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	788,654	732,322	675,404
Real Estate - Commercial and Farmland [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	788,654	732,322	675,404
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	298	309	230
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	154,369	147,966	158,608
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	402,677	351,997	287,874
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	9,575	9,012	9,578
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	189,109	176,395	170,342
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	12,104	19,401	17,870
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	20,522	27,242	30,902
Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	357,685	346,480	332,124
Real Estate - Residential [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	357,685	346,480	332,124
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	498	464	414
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	63,078	71,254	75,752
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	137,518	114,418	93,018
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	13,104	13,788	13,839
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	110,244	113,591	109,269
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,666	9,672	12,461
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	22,577	23,292	27,306
Real Estate - Residential [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade		1	65
Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	36,923	40,178	41,431
Consumer Installment Loans [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	36,923	40,178	41,431
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 10 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	6,883	7,597	7,226
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 15 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,527	1,591	1,260
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	19,586	21,361	23,537
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 23 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	165	70	23
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 25 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	7,497	7,576	7,035
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 30 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	159	488	554
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 40 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,104	1,495	1,776
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 50 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	0		20
Consumer Installment Loans [Member] | Non-Covered Loan [Member] | 60 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	29,534	43,239	17,071
Other [Member] | Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	29,534	43,239	17,071
Other [Member] | Non-Covered Loan [Member] | 20 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 29,534	$ 43,239	$ 17,071