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	$ 74,933	$ 68,208
Less: accumulated depreciation	35,563	32,830
Premises and equipment, net	39,370	35,378
Land [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	4,726	4,726
Premises and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	37,673	35,839
Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	25,517	24,137
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 7,017	$ 3,506