Loans - Additional Information (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 797,622,000	$ 745,441,000	$ 646,439,000
Non-accrual	2,310,000	2,411,000
Balances of loans sold to and serviced for others	371,800,000	383,700,000
Unpaid principal balances of loans sold to and serviced for others	415,500,000	426,900,000
Loan outstanding to related parties	18,432,000	17,992,000		$ 14,631,000
Doubtful or Loss [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	0	0
30-59 days [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due and Accruing	1,439,000	669,000
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	33,900,000	37,000,000
Non-accrual	1,000,000	1,100,000
Acquired Loans [Member] | 30-59 days [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due and Accruing	1,000,000	200,000
Acquired Loans [Member] | 90 or more days [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due and Accruing	$ 0	$ 0