Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)	$ 5,475	$ 6,776
Core deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)	4,340	5,298
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)	1,086	1,410
Non-compete agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)	$ 49	$ 68