Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total cost	$ 90,518	$ 79,411
Accumulated depreciation	(29,720)	(26,950)
Net premise and equipment	60,798	52,461
Land [Member]
Property, Plant and Equipment [Line Items]
Total cost	19,475	16,550
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Total cost	55,341	49,066
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total cost	$ 15,702	$ 13,795