DERIVATIVES - Summary of Derivative Financial Instruments and Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 17,479,999	$ 17,683,691
Derivative Asset	219,745	212,970
Derivative liabilities	219,745	212,977
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,348,703	2,430,587
Derivative Asset	18,399	84,694
Derivative liabilities	55,970	7,508
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,348,703	2,430,587
Derivative Asset	55,970	7,508
Derivative liabilities	18,399	84,701
Foreign Exchange | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	6,406,294	6,423,085
Derivative Asset	85,265	67,988
Derivative liabilities	60,111	52,780
Foreign Exchange | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	6,376,299	6,399,432
Derivative Asset	60,111	52,780
Derivative liabilities	$ 85,265	$ 67,988