Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 90,026	$ 74,933
Less: accumulated depreciation	40,504	35,563
Premises and equipment, net	49,522	39,370
Land [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	7,324	4,726
Premises and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	48,563	37,673
Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	30,125	25,517
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 4,014	$ 7,017