PREMISES AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment, Net [Abstract]
Premises and equipment, gross	$ 305,539	$ 312,434
Accumulated depreciation	(144,888)	(146,779)
Premises and equipment, net	160,651	165,655
Land and Land Improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Premises and equipment, gross	31,884	29,070
Bank Premises [Member]
Property, Plant and Equipment, Net [Abstract]
Premises and equipment, gross	151,724	149,217
Equipment and Construction in Progress [Member]
Property, Plant and Equipment, Net [Abstract]
Premises and equipment, gross	85,391	93,013
Construction in Progress [Member]
Property, Plant and Equipment, Net [Abstract]
Premises and equipment, gross	4,786	6,226
Operating Lease Right-of-Use Assets [Member]
Property, Plant and Equipment, Net [Abstract]
Premises and equipment, gross	$ 31,754	$ 34,908