Premises and Equipment, Net - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 144,231	$ 136,207
Accumulated depreciation	(54,483)	(49,144)
Premises and equipment, net	89,748	87,063
Land and land improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	12,356	12,574
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	61,409	60,919
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	15,261	15,026
Software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 55,205	$ 47,688