Premises and Equipment, Net - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 238,099	$ 214,227
Accumulated depreciation	(83,429)	(79,478)
Premises and equipment, net	154,670	134,749
Land and land improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	12,356	12,356
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	120,971	105,986
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	28,272	25,694
Software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 76,500	$ 70,191