Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Parenthetical) (Detail) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	$ 7,017,000	$ 6,546,000	$ 5,097,000
Purchased Credit Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	$ 1,853,000	$ 2,178,000	$ 2,422,000