Fair Value Disclosures - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets transfer between Level 2 and Level 3	$ 0	$ 0	$ 0
Impaired loans carrying value	27,371,000	28,601,000
Impaired loans valuation reserves	5,012,000	5,071,000
Impaired loans net fair value	22,359,000
Other real estate owned, total	413,000	$ 153,000
Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loan held-for-sale, fair value	$ 26,702,000
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage	5.00%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage	25.00%