COMMITMENTS AND CONTINGENCIES - Schedule of Outstanding Off-balance sheet Arrangements (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Other Commitments [Line Items]
Commitment amount	$ 89,230	$ 86,351
Commitments to extend credit
Other Commitments [Line Items]
Commitment amount	87,127	84,206
Letters of credit
Other Commitments [Line Items]
Commitment amount	1,977	1,998
Risk participation agreements
Other Commitments [Line Items]
Commitment amount	17	39
Loans sold with recourse
Other Commitments [Line Items]
Commitment amount	85	82
Marketing rights
Other Commitments [Line Items]
Commitment amount	$ 24	$ 26