Non-performing Assets and Impaired Loans - Loans by Credit Grades (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total	$ 1,100,070	$ 1,067,935
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	528,031	504,584
Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	173,514	156,262
Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	230,225	224,713
Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	833	400
Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	21,347	21,289
Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	102,112	101,920
Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	291,687	283,732
Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	180,849	176,068
Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	8,692	9,508
Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	102,146	98,156
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	280,352	279,619
Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	30,556	29,983
Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	270	294
Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	131,394	131,384
Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	118,132	117,958
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,051,985	1,019,365
Percentage of total loans	95.63%	95.45%
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	490,271	466,820
Pass [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	163,274	146,085
Pass [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	213,918	208,625
Pass [Member] | Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	738	400
Pass [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	19,984	19,858
Pass [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	92,357	91,852
Pass [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	285,329	277,586
Pass [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	174,769	170,202
Pass [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	8,414	9,228
Pass [Member] | Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	102,146	98,156
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	276,386	274,959
Pass [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	30,247	29,781
Pass [Member] | Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	270	294
Pass [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	130,755	130,851
Pass [Member] | Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	115,114	114,033
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	15,106	13,861
Percentage of total loans	1.37%	1.30%
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	15,106	13,861
Special Mention [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	2,667	2,231
Special Mention [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,211	5,047
Special Mention [Member] | Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	95
Special Mention [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	88	91
Special Mention [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,045	6,492
Special Mention [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Special Mention [Member] | Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	32,978	34,709
Percentage of total loans	3.00%	3.25%
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	22,654	23,903
Substandard [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	7,573	7,946
Substandard [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	10,096	11,041
Substandard [Member] | Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Substandard [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,275	1,340
Substandard [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,710	3,576
Substandard [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,358	6,146
Substandard [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,080	5,866
Substandard [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	278	280
Substandard [Member] | Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,966	4,660
Substandard [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	309	202
Substandard [Member] | Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Substandard [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	639	533
Substandard [Member] | Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,018	3,925
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Percentage of total loans	0.00%	0.00%
Doubtful [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total
Doubtful [Member] | Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total