Premises and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 4,739	$ 3,465	$ 3,507
Lease expiration year	Jan. 01, 2054
Rental expense	$ 3,900	2,700	2,500
Two Directors
Property, Plant and Equipment [Line Items]
Rental expense for premises leases with two directors	$ 200	$ 200	$ 200