Premises and Equipment - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Renewal_Terms Lease	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Depreciation on premises and equipment	$ 3,215	$ 2,759	$ 2,659
Rental expense, net of rental income	$ 773	699	736
Sale leaseback transaction, lease term	17 years
Sale leaseback transaction, number of automatic renewals | Renewal_Terms	2
Sale leaseback transaction, two automatic lease renewal, period	5 years
Sale leaseback transaction, sale of property, amount	$ 1,200
Sale leaseback transaction, deferred gain	489
Sale leaseback transaction, gain recognized	$ 25	$ 22	$ 19
Facilities [Member]
Property, Plant and Equipment [Line Items]
Non cancelable operating leases having remaining term less than one year | Lease	19
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Non cancelable operating leases having remaining term less than one year | Lease	10
Capital Addition Purchase Commitments [Member] | Altoona, Pennsylvania [Member]
Property, Plant and Equipment [Line Items]
Contractual commitment to construct a branch facility	$ 2,279
Construction in process	2,229
Capital Addition Purchase Commitments [Member] | Ashtabula, Ohio [Member]
Property, Plant and Equipment [Line Items]
Contractual commitment to construct a branch facility	1,706
Construction in process	$ 1,557