PREMISES AND EQUIPMENT - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 314,095	$ 216,878
Accumulated depreciation	(80,993)	(71,468)
Premises and equipment, net	233,102	145,410
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	74,868	49,518
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	167,837	110,623
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	69,108	53,425
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 2,282	$ 3,312