Loans and Leases - Credit Quality Indicators (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	$ 1,586,994	$ 1,541,484	$ 1,499,993
Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	9,880	8,459
Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	20,663	18,866
Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	54,166	54,169
Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	762,988	716,422
Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	191,886	219,350
Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	29,892	31,381
Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	116,597	101,941
Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment		393
Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	1,186,072	1,150,981
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	399,194	388,558
Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	1,728	1,945
Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	400,922	390,503
Commercial, Financial and Agricultural [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	447,993	422,816	439,907
Commercial, Financial and Agricultural [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	4,533	4,763
Commercial, Financial and Agricultural [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	7,574	6,051
Commercial, Financial and Agricultural [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	28,620	34,650
Commercial, Financial and Agricultural [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	276,339	251,203
Commercial, Financial and Agricultural [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	66,948	84,201
Commercial, Financial and Agricultural [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	13,439	10,095
Commercial, Financial and Agricultural [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	50,540	31,508
Commercial, Financial and Agricultural [Member] | Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment		345
Commercial, Financial and Agricultural [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	447,993	422,816
Real Estate-Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	626,060	600,353
Real Estate-Commercial [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	1,858	2,014
Real Estate-Commercial [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	9,135	8,515
Real Estate-Commercial [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	16,610	17,758
Real Estate-Commercial [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	417,051	384,061
Real Estate-Commercial [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	115,956	113,181
Real Estate-Commercial [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	12,660	19,445
Real Estate-Commercial [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	52,790	55,331
Real Estate-Commercial [Member] | Grade: 9. Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment		48
Real Estate-Commercial [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	626,060	600,353
Real Estate-Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	76,735	90,493
Real Estate-Construction [Member] | Grade: 1. Cash secured/ 2. Fully secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	3,489	1,682
Real Estate-Construction [Member] | Grade: 3. Strong [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	3,954	4,300
Real Estate-Construction [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	8,689	1,500
Real Estate-Construction [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	44,643	54,464
Real Estate-Construction [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	4,307	16,084
Real Estate-Construction [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	2,053
Real Estate-Construction [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	9,600	12,463
Real Estate-Construction [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	76,735	90,493
Real Estate-Residential Secured for Business Purpose [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	35,284	37,319	32,329
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 4. Satisfactory [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	247	261
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 5. Acceptable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	24,955	26,694
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 6. Pre-watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	4,675	5,884
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 7. Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	1,740	1,841
Real Estate-Residential Secured for Business Purpose [Member] | Grade: 8. Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	3,667	2,639
Real Estate-Residential Secured for Business Purpose [Member] | Internally Assigned Grades [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	35,284	37,319
Real Estate-Residential Secured for Personal Purpose [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	162,352	149,164
Real Estate-Residential Secured for Personal Purpose [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	161,569	148,063
Real Estate-Residential Secured for Personal Purpose [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	783	1,101
Real Estate-Residential Secured for Personal Purpose [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	162,352	149,164
Real Estate-Home Equity Secured for Personal Purpose [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	98,880	95,345
Real Estate-Home Equity Secured for Personal Purpose [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	98,776	95,245
Real Estate-Home Equity Secured for Personal Purpose [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	104	100
Real Estate-Home Equity Secured for Personal Purpose [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	98,880	95,345
Loans to Individuals [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	31,564	40,000	43,598
Loans to Individuals [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	31,347	39,645
Loans to Individuals [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	217	355
Loans to Individuals [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	31,564	40,000
Lease Financings [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	108,126	105,994	91,621
Lease Financings [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	107,502	105,605
Lease Financings [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	624	389
Lease Financings [Member] | Performing and Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases held for investment	$ 108,126	$ 105,994