Loans and Allowance for Loan Losses - Summary of Credit Quality Indicate Financial Receivable (Non-Covered Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	$ 1,450,635	$ 1,332,086
Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1,450,635	1,332,086
Non-Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	32,993	23,930
Non-Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	236,500	261,489
Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	641,950	485,364
Non-Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	31,433	29,730
Non-Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	399,210	386,365
Non-Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	35,298	41,584
Non-Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	72,994	102,947
Non-Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	257	677
Commercial, financial & agricultural [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	174,217	142,960
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	174,217	142,960
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	24,623	17,213
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	11,316	15,379
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	79,522	60,631
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	42	32
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	49,071	42,815
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	2,343	2,509
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	7,200	4,258
Commercial, financial & agricultural [Member] | Non-Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	100	123
Real estate - construction & development [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	114,199	130,270
Real estate - construction & development [Member] | Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	114,199	130,270
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		20
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	4,373	5,391
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	31,413	32,654
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	8,521	7,994
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	52,577	62,029
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	3,394	2,027
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	13,765	19,864
Real estate - construction & development [Member] | Non-Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	156	291
Real estate - commercial and farmland [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	732,322	672,765
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	732,322	672,765
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	309	235
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	147,966	151,068
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	351,997	272,241
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	9,012	10,679
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	176,395	163,554
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	19,401	21,490
Real estate - commercial and farmland [Member] | Non-Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	27,242	53,498
Real estate - residential [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	346,480	330,727
Real estate - residential [Member] | Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	346,480	330,727
Real estate - residential [Member] | Non-Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	464	252
Real estate - residential [Member] | Non-Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	71,254	88,586
Real estate - residential [Member] | Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	114,418	80,989
Real estate - residential [Member] | Non-Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	13,788	10,997
Real estate - residential [Member] | Non-Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	113,591	110,786
Real estate - residential [Member] | Non-Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	9,672	15,001
Real estate - residential [Member] | Non-Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	23,292	23,867
Real estate - residential [Member] | Non-Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1	249
Consumer installment loans [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	40,178	37,296
Consumer installment loans [Member] | Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	40,178	37,296
Consumer installment loans [Member] | Non-Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	7,597	6,210
Consumer installment loans [Member] | Non-Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1,591	1,065
Consumer installment loans [Member] | Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	21,361	20,781
Consumer installment loans [Member] | Non-Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	70	28
Consumer installment loans [Member] | Non-Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	7,576	7,181
Consumer installment loans [Member] | Non-Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	488	557
Consumer installment loans [Member] | Non-Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1,495	1,460
Consumer installment loans [Member] | Non-Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		14
Other Loans [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	43,239	18,068
Other Loans [Member] | Non-Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	43,239	18,068
Other Loans [Member] | Non-Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	$ 43,239	$ 18,068