Non-performing Loans 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	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	$ 10,895	$ 12,262
Loans Past Due Over 90 Days Still Accruing	1	28
Non-Performing TDRs	2,857	3,172
Performing TDRs	1,231	1,218
Total Non-Performing Loans	14,984	16,680
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	4,099	5,030
Non-Performing TDRs	1,615	1,915
Performing TDRs	60	60
Total Non-Performing Loans	5,774	7,005
Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	1,089	1,749
Total Non-Performing Loans	1,089	1,749
Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	2,934	3,034
Non-Performing TDRs	1,615	1,915
Performing TDRs	60	60
Total Non-Performing Loans	4,609	5,009
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	76	176
Total Non-Performing Loans	76	176
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	3,950	4,354
Loans Past Due Over 90 Days Still Accruing	1	1
Non-Performing TDRs	1,061	1,074
Performing TDRs	962	808
Total Non-Performing Loans	5,974	6,237
Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	3,950	4,354
Loans Past Due Over 90 Days Still Accruing	1	1
Non-Performing TDRs	815	824
Performing TDRs	962	808
Total Non-Performing Loans	5,728	5,987
Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Performing TDRs	246	250
Total Non-Performing Loans	246	250
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	2,846	2,878
Loans Past Due Over 90 Days Still Accruing		27
Non-Performing TDRs	181	183
Performing TDRs	209	350
Total Non-Performing Loans	3,236	3,438
Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	496	541
Total Non-Performing Loans	496	541
Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	739	601
Loans Past Due Over 90 Days Still Accruing		27
Total Non-Performing Loans	739	628
Consumer [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual	1,611	1,736
Non-Performing TDRs	181	183
Performing TDRs	209	350
Total Non-Performing Loans	$ 2,001	$ 2,269