Premises and Equipment - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Accumulated depreciations and amortization	$ (85,545)	$ (80,728)
Total	86,995	70,016
Land
Property, Plant and Equipment [Line Items]
Premise and equipment, gross	9,245	9,311
Premises
Property, Plant and Equipment [Line Items]
Premise and equipment, gross	95,272	75,633
Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Premise and equipment, gross	$ 68,023	$ 65,800