Loans and Allowance for Loan Losses - Additional Information (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($) Loans	Dec. 31, 2015 USD ($) Loans
Financing Receivable, Recorded Investment [Line Items]
Threshold percentage of repayment derived from non-affiliated third party (as a percent)	50.00%
Impaired loans, net	$ 4,300	$ 4,900
Troubled debt restructuring number of loans | Loans	1	2
Troubled debt restructurings subsequently default within twelve months	$ 57	$ 1,060
Consumer mortgage loans	1,365	639
Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Potential problem loans	$ 25,300	$ 25,200
Residential 1-4 Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Amortization period, lower range	15 years
Amortization period, upper range	30 years
Maturity period, lower range	5 years
Maturity period, upper range	15 years