Loans and the Allowance for Credit Losses - Recorded Investment in Non-Accrual Loans and TDRs (Parenthetical) (Detail)	Sep. 30, 2016 USD ($) Borrowers	Dec. 31, 2015 USD ($) Borrowers
Financing Receivable, Impaired [Line Items]
Number of borrowers with loans greater than one million | Borrowers	2	3
Borrowers with large amount of loans outstanding, minimum amount of loans per borrower	$ 1,000,000	$ 1,000,000
Loans acquired with deteriorated credit quality	13,923,000	$ 9,289,000
Your Community Bankshares, Inc [Member]
Financing Receivable, Impaired [Line Items]
Loans acquired with deteriorated credit quality	6,500,000
Non Accrual [Member] | Your Community Bankshares, Inc [Member]
Financing Receivable, Impaired [Line Items]
Loans acquired with deteriorated credit quality	$ 2,700,000