Allowance for Loan Losses - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of nonperforming loans	90 days
Non-accruing loans excluded from impaired loan	$ 465	$ 95
Non-accruing loans accrued interest	$ 5	$ 5
Number of trouble debt restructurings | Contract	16	16
Aggregate balance of trouble debt restructuring	$ 3,200	$ 3,500