DERIVATIVES - Disclosure by Type of Financial Instrument (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 272,606	$ 112,616
Derivative Liability, Fair Value, Gross Asset	(402,480)	(188,395)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		(75,779)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(129,874)
Fair Value Hedges \| Matched interest rate swaps \| Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	184,991	73,444
Derivative Liability, Fair Value, Gross Asset	(385,088)	(147,193)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		73,749
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(200,097)
Fair Value Hedges \| Foreign Exchange [Member] \| Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	87,615	39,172
Derivative Liability, Fair Value, Gross Asset	(17,392)	(41,202)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 70,223	$ (2,030)

Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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