Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment, Net, by Type [Abstract]
Land & land improvements	$ 10,514	$ 8,909
Buildings	44,405	38,643
Furniture and equipment	32,247	31,081
Premises and equipment, gross	87,166	78,633
Less: Accumulated depreciation	(38,068)	(35,518)
Premises and equipment less depreciation, gross	49,098	43,115
Construction in progress	350	696
Total premises and equipment	$ 49,448	$ 43,811