Loans and Allowance for Loan Losses - Summary of Credit Quality Indicate Financial Receivable (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
Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	507,712	571,489
Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		2,539
Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	2,323	2,436
Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	84,918	56,672
Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	12,830	5,477
Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	184,830	219,568
Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	62,106	78,724
Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	160,705	206,045
Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		28
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] | Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	32,606	41,867
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		442
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		29
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	3,997	4,807
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	28
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	10,013	15,531
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	4,294	5,882
Commercial, financial & agricultural [Member] | Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	14,274	15,176
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] | Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	70,184	77,077
Real estate - construction & development [Member] | Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	39	52
Real estate - construction & development [Member] | Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	12,194	5,751
Real estate - construction & development [Member] | Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1,174	1,177
Real estate - construction & development [Member] | Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	19,216	21,142
Real estate - construction & development [Member] | Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	7,214	10,654
Real estate - construction & development [Member] | Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	30,347	38,273
Real estate - construction & development [Member] | Covered Loan [Member] | 50
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		28
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] | Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	278,506	321,257
Real estate - commercial and farmland [Member] | Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1,640	1,755
Real estate - commercial and farmland [Member] | Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	37,098	26,211
Real estate - commercial and farmland [Member] | Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	9,576	3,262
Real estate - commercial and farmland [Member] | Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	114,849	137,981
Real estate - commercial and farmland [Member] | Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	38,665	49,642
Real estate - commercial and farmland [Member] | Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	76,678	102,406
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] | Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	125,056	127,644
Real estate - residential [Member] | Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		1,329
Real estate - residential [Member] | Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	644	586
Real estate - residential [Member] | Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	31,337	19,216
Real estate - residential [Member] | Covered Loan [Member] | 23
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	2,052	1,038
Real estate - residential [Member] | Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	40,194	43,606
Real estate - residential [Member] | Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	11,883	12,374
Real estate - residential [Member] | Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	38,946	49,495
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] | Covered Loan [Member]
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	1,360	3,644
Consumer installment loans [Member] | Covered Loan [Member] | 10
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		768
Consumer installment loans [Member] | Covered Loan [Member] | 15
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade		14
Consumer installment loans [Member] | Covered Loan [Member] | 20
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	292	687
Consumer installment loans [Member] | Covered Loan [Member] | 25
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	558	1,308
Consumer installment loans [Member] | Covered Loan [Member] | 30
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	50	172
Consumer installment loans [Member] | Covered Loan [Member] | 40
Finance Receivable Transferred To Held For Sale [Line Items]
Loans portfolio by risk grade	$ 460	$ 695