Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements Disclosure [Line Items]
Percentage of securities using market-based information	99.90%
Percentage of securities using model-based techniques	0.10%
Minimum reserves for commercial loan	$ 500,000
Transfer of equity security to non-marketable equity securities, included in other assets	56,000
Impaired loans, carrying amount	70,689,000	$ 69,450,000
Allocated allowance for loan losses	2,650,000
Fair value of allocated allowance	3,828,000
Estimated costs to sell	39,000
Provision for fair value measurements included in allowance for loan losses	1,494,000
Carrying amount of OREO	9,960,000
Written down of OREO	6,950,000
Fair value of OREO	7,831,000
Estimated cost to sell OREO	881,000
Loss from OREO included in earnings	$ 3,010,000
Short-term borrowings approximate fair value for amounts that mature, days, less than	90 days
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Impaired loans, carrying amount	$ 6,439,000
Allocated allowance for loan losses	3,828,000	1,705,000
Fair value of OREO	7,831,000	8,060,000
Assets Still Held [Member]
Fair Value Measurements Disclosure [Line Items]
Change in unrealized gains or losses included in earnings relating to assets still held	$ 0	$ 0