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DERIVATIVE FINANCIAL INSTRUMENTS - Fair Value of Derivative Instruments (Details) $ in Thousands	Jun. 30, 2020 USD ($)	Apr. 30, 2020 USD ($)	Dec. 31, 2019 USD ($) instrument
Derivative [Line Items]
Notional	$ 833,752		$ 502,172
Total derivatives	(18,979)		966
Designated as Hedging Instrument
Derivative [Line Items]
Notional			75,000
Total derivatives		$ 1,300
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional			427,172
Derivative Liability			1,725
Other liabilities \| Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability			(759)
Interest rate products \| Other assets \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	65,626		71,804
Derivative Asset	6,579		$ 2,520
Interest rate products \| Other liabilities \| Designated as Hedging Instrument
Derivative [Line Items]
Count \| instrument			3
Notional			$ 75,000
Derivative Liability			(759)
Interest rate products \| Other liabilities \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	65,626		71,804
Derivative Liability	(7,404)		(2,688)
Risk participation agreements \| Other liabilities \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	4,449		4,524
Derivative Liability	(14)		(4)
Interest rate lock commitments with customers \| Other assets \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	287,204		99,057
Derivative Asset	8,218		1,768
Interest rate lock commitments with customers \| Other liabilities \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	20,260		28,505
Derivative Liability	(132)		(191)
Forward sale commitments \| Other assets \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	44,840		61,301
Derivative Asset	446		596
Forward sale commitments \| Other liabilities \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	232,570		90,177
Derivative Liability	(1,467)		$ (276)
Financial derivatives related to sales of certain Visa Class B shares \| Other liabilities \| Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional	113,177
Derivative Liability	$ (25,205)