Loans - Summary of Covered Past Due Financial Receivables (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 30-59 Days Past Due	$ 27,400	$ 40,300
Total Loans	1,492,753	1,450,635	1,323,844
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans 30-59 Days Past Due	20,603	21,536	22,215
Loans 60-89 Days Past Due	4,383	14,479	11,784
Loans 90 or More Days Past Due	86,249	108,072	150,368
Total Loans Past Due	111,235	144,087	184,367
Current Loans	349,489	363,625	469,010
Total Loans	460,724	507,712	653,377
Loans 90 Days or More Past Due and Still Accruing	146	3,301	4,285
Commercial, financial & agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	180,888	174,217	149,320
Commercial, financial & agricultural [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans 30-59 Days Past Due	756	2,390	682
Loans 60-89 Days Past Due	314	1,105	430
Loans 90 or More Days Past Due	7,270	10,612	14,229
Total Loans Past Due	8,340	14,107	15,341
Current Loans	20,228	18,499	27,816
Total Loans	28,568	32,606	43,157
Loans 90 Days or More Past Due and Still Accruing	98	98	549
Real estate - construction & development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	130,161	114,199	122,331
Real estate - construction & development [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans 30-59 Days Past Due	3,971	1,584	2,704
Loans 60-89 Days Past Due	876	2,592	778
Loans 90 or More Days Past Due	17,415	19,656	32,302
Total Loans Past Due	22,262	23,832	35,784
Current Loans	34,852	46,352	57,646
Total Loans	57,114	70,184	93,430
Loans 90 Days or More Past Due and Still Accruing		1,077	909
Real estate - commercial & farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	766,227	732,322	658,054
Real estate - commercial & farmland [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans 30-59 Days Past Due	10,227	11,451	12,905
Loans 60-89 Days Past Due	2,837	7,373	6,994
Loans 90 or More Days Past Due	42,464	52,570	68,282
Total Loans Past Due	55,528	71,394	88,181
Current Loans	204,631	207,112	262,063
Total Loans	260,159	278,506	350,244
Loans 90 Days or More Past Due and Still Accruing		1,347	2,583
Real estate - residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	355,716	346,480	328,053
Real estate - residential [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans 30-59 Days Past Due	5,608	6,066	5,859
Loans 60-89 Days Past Due	345	3,396	3,514
Loans 90 or More Days Past Due	18,895	24,976	34,870
Total Loans Past Due	24,848	34,438	44,243
Current Loans	88,820	90,618	118,525
Total Loans	113,668	125,056	162,768
Loans 90 Days or More Past Due and Still Accruing	48	779	3
Consumer installment loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	37,335	40,178	42,085
Consumer installment loans [Member] | Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans 30-59 Days Past Due	41	45	65
Loans 60-89 Days Past Due	11	13	68
Loans 90 or More Days Past Due	205	258	685
Total Loans Past Due	257	316	818
Current Loans	958	1,044	2,960
Total Loans	1,215	1,360	3,778
Loans 90 Days or More Past Due and Still Accruing			$ 241