Non-performing Assets and Impaired Loans - Non-accrual, Loans Past Due Over 90 Days Still on Accrual, and Troubled Debt Restructured ("TDRs") by Class of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	$ 12,262	$ 15,312
Loans Past Due Over 90 Days Still Accruing	28	115
Non-Performing TDRs	3,172	2,643
Performing TDRs	1,218	4,372
Total Non-Performing Loans	16,680	22,442
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	5,030	10,024
Non-Performing TDRs	1,915	1,221
Performing TDRs	60	610
Total Non-Performing Loans	7,005	11,855
Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	1,749	1,773
Performing TDRs		44
Total Non-Performing Loans	1,749	1,817
Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	3,034	7,439
Non-Performing TDRs	1,915	217
Performing TDRs	60	566
Total Non-Performing Loans	5,009	8,222
Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	71
Total Non-Performing Loans	71
Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	176	812
Non-Performing TDRs		1,004
Total Non-Performing Loans	176	1,816
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	4,354	2,297
Loans Past Due Over 90 Days Still Accruing	1	40
Non-Performing TDRs	1,074	1,031
Performing TDRs	808	2,526
Total Non-Performing Loans	6,237	5,894
Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	4,354	2,297
Loans Past Due Over 90 Days Still Accruing	1	40
Non-Performing TDRs	824	765
Performing TDRs	808	2,526
Total Non-Performing Loans	5,987	5,628
Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Performing TDRs	250	266
Total Non-Performing Loans	250	266
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	2,878	2,991
Loans Past Due Over 90 Days Still Accruing	27	75
Non-Performing TDRs	183	391
Performing TDRs	350	1,236
Total Non-Performing Loans	3,438	4,693
Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	541	227
Loans Past Due Over 90 Days Still Accruing		10
Total Non-Performing Loans	541	237
Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	601	557
Loans Past Due Over 90 Days Still Accruing	27	47
Total Non-Performing Loans	628	604
Consumer [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	1,736	2,207
Loans Past Due Over 90 Days Still Accruing		18
Non-Performing TDRs	183	391
Performing TDRs	350	1,236
Total Non-Performing Loans	$ 2,269	$ 3,852