Premises and Equipment - Summary of Cost and Accumulated Depreciation and Amortization of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Land and improvements	$ 2,676	$ 1,176
Buildings and leasehold improvements	4,569	3,670
Equipment	3,722	3,375
Construction-in-progress	611	14
Property plant and equipment, gross	11,578	8,235
Less accumulated depreciation and amortization	(5,298)	(5,330)
Property plant and equipment, net	$ 6,280	$ 2,905
Buildings and Leasehold Improvements [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	5 years
Buildings and Leasehold Improvements [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	50 years
Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	3 years
Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	10 years