Allowance for Loan Losses - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Category	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of categories occupied under commercial real estate loans | Category	2
Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired TDRs Loans	$ 29,269,000	$ 45,676,000	$ 56,739,000
Additional funds in TDRs	35,000	54,000	25,000
PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired TDRs Loans	1,396,000	1,307,000	901,000
Obligations to lend additional funds on TDRs	$ 0	$ 0	$ 0
Minimum [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Period of collateral payment of loan	3 months
Maximum [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Period of collateral payment of loan	12 months