Loans and Allowance for Credit Losses - Troubled Debt Restructurings Identified During Period (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Contract	Dec. 31, 2012 Contract	Dec. 31, 2011 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	82	60	51
Extend Maturity	$ 4,390	$ 6,776	$ 19,856
Modify Rate	2,018	4,724	25,302
Modify Payments	3,971	10,332	5,130
Others	0	54	0
Total Pre-Modification Outstanding Recorded Investment	10,379	21,886	50,288
Post-Modification Outstanding Recorded Investment	7,713	22,221	31,993
Specific Reserve	1,101	4,915	1,315
Commercial, financial, agricultural and other [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	14	12	13
Extend Maturity	3,462	1,599	100
Modify Rate	0	187	475
Modify Payments	1,677	9,476	2,218
Others	0	0	0
Total Pre-Modification Outstanding Recorded Investment	5,139	11,262	2,793
Post-Modification Outstanding Recorded Investment	3,104	11,335	2,749
Specific Reserve	906	4,237	743
Real estate construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts		2	6
Extend Maturity		1,697	2,554
Modify Rate		0	86
Modify Payments		0	0
Others		0	0
Total Pre-Modification Outstanding Recorded Investment		1,697	2,640
Post-Modification Outstanding Recorded Investment		2,133	2,852
Specific Reserve		200	0
Residential real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	46	25	10
Extend Maturity	347	200	0
Modify Rate	418	132	515
Modify Payments	2,116	697	601
Others	0	48	0
Total Pre-Modification Outstanding Recorded Investment	2,881	1,077	1,116
Post-Modification Outstanding Recorded Investment	2,316	973	1,100
Specific Reserve	161	69	65
Commercial real estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	5	4	22
Extend Maturity	571	3,280	17,202
Modify Rate	1,499	4,308	24,226
Modify Payments	145	71	2,311
Others	0	0	0
Total Pre-Modification Outstanding Recorded Investment	2,215	7,659	43,739
Post-Modification Outstanding Recorded Investment	2,184	7,607	25,292
Specific Reserve	34	409	507
Loans to individuals [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	17	17
Extend Maturity	10	0
Modify Rate	101	97
Modify Payments	33	88
Others	0	6
Total Pre-Modification Outstanding Recorded Investment	144	191
Post-Modification Outstanding Recorded Investment	109	173
Specific Reserve	$ 0	$ 0