Loans - Schedule of Loans Not Rated by Class of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	$ 140,038	$ 140,165
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	889	770
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	923	1,262
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	126,674	125,372
Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	1,169	3,493
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	10,383	9,268
Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	139,305	139,493
Performing [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	889	770
Performing [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	923	1,262
Performing [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	125,941	124,700
Performing [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	1,169	3,493
Performing [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	10,383	9,268
Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	733	672
Nonperforming [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans not rated by class of loans	$ 733	$ 672