Fair Value Disclosures - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets transfer between Level 1 and Level 2	$ 0	$ 0	$ 0	$ 0	$ 0
Assets transfer between Level 2 and Level 3	0	0	0	0	0
Impaired loans carrying value	21,489,000	38,904,000	21,489,000	38,904,000	27,371,000
Impaired loans valuation reserves	4,543,000	7,102,000	4,543,000	7,102,000	5,012,000
Impaired loans net fair value	16,946,000		16,946,000
Other real estate owned, total	$ 2,023,000	$ 124,000	$ 2,023,000	$ 124,000	$ 413,000
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%