Loans and Allowance for Loan Losses - Allowance for Loan Losses Outstanding by Impairment Methodology (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	$ 5,985	$ 8,127
Collectively evaluated for impairment	35,681	32,762
Non-residential Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	323	202
Collectively evaluated for impairment	4,338	4,204
Non-residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	323	1,518
Collectively evaluated for impairment	9,598	8,098
Residential Real Estate Permanent Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	399	407
Collectively evaluated for impairment	2,749	2,541
Residential Real Estate All Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	839	743
Collectively evaluated for impairment	5,886	5,526
Non-consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	3,365	4,671
Collectively evaluated for impairment	8,389	8,100
Consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	445	372
Collectively evaluated for impairment	2,197	2,032
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	291	214
Collectively evaluated for impairment	2,357	2,145
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment	$ 167	$ 116