Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 98,396	$ 84,089
Accumulated depreciation	(49,269)	(45,923)
Premises and equipment, net	49,127	38,166
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	8,699	6,193
Premises
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	52,968	44,690
Furniture and Equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	29,543	26,661
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 7,186	$ 6,545