Loans - Summary of Credit Quality Indicate Financial Receivable (Covered Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	$ 1,492,753	$ 1,450,635	$ 1,323,844
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	460,724	507,712	653,377
Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			1,719
Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,270	2,323	2,402
Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	78,056	84,918	53,255
Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	12,422	12,830	6,994
Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	170,675	184,830	283,172
Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	51,871	62,106	74,692
Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	145,430	160,705	231,143
Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Covered Loans [Member] | 60
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Commercial, financial & agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	180,888	174,217	149,320
Commercial, financial & agricultural [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	28,568	32,606	43,157
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			216
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			26
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	3,117	3,997	4,592
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	75	28	11
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,135	10,013	17,075
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	2,979	4,294	2,400
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	14,262	14,274	18,837
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Commercial, financial & agricultural [Member] | Covered Loans [Member] | 60
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real estate - construction & development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	130,161	114,199	122,331
Real estate - construction & development [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	57,114	70,184	93,430
Real estate - construction & development [Member] | Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			9
Real estate - construction & development [Member] | Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	34	39	51
Real estate - construction & development [Member] | Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	11,106	12,194	5,541
Real estate - construction & development [Member] | Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,248	1,174	1,534
Real estate - construction & development [Member] | Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	10,184	19,216	31,707
Real estate - construction & development [Member] | Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	4,457	7,214	10,628
Real estate - construction & development [Member] | Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	30,085	30,347	43,960
Real estate - construction & development [Member] | Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real estate - construction & development [Member] | Covered Loans [Member] | 60
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real estate - commercial & farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	766,227	732,322	658,054
Real estate - commercial & farmland [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	260,159	278,506	350,244
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,598	1,640	1,734
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	36,020	37,098	24,784
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	9,153	9,576	3,763
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	110,985	114,849	157,031
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	35,601	38,665	49,518
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	66,802	76,678	113,414
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real estate - commercial & farmland [Member] | Covered Loans [Member] | 60
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	355,716	346,480	328,053
Real estate - residential [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	113,668	125,056	162,768
Real estate - residential [Member] | Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			1,036
Real estate - residential [Member] | Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	638	644	579
Real estate - residential [Member] | Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	27,547	31,337	17,716
Real estate - residential [Member] | Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,946	2,052	1,686
Real estate - residential [Member] | Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	40,863	40,194	75,809
Real estate - residential [Member] | Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	8,784	11,883	12,044
Real estate - residential [Member] | Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	33,890	38,946	53,898
Real estate - residential [Member] | Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Real estate - residential [Member] | Covered Loans [Member] | 60
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	37,335	40,178	42,085
Consumer installment loans [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	1,215	1,360	3,778
Consumer installment loans [Member] | Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			458
Consumer installment loans [Member] | Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade			12
Consumer installment loans [Member] | Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	266	292	622
Consumer installment loans [Member] | Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Consumer installment loans [Member] | Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	508	558	1,550
Consumer installment loans [Member] | Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	50	50	102
Consumer installment loans [Member] | Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade	391	460	1,034
Consumer installment loans [Member] | Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Consumer installment loans [Member] | Covered Loans [Member] | 60
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	22,426	43,239	24,001
Other [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 10
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 15
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 20
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 23
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 25
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 30
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 40
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade
Other [Member] | Covered Loans [Member] | 60
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans portfolio by risk grade