COMMITMENTS AND CONTINGENCIES - Schedule of Outstanding Off-balance sheet Arrangements (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Other Commitments [Line Items]
Commitment amount	$ 75,040	$ 71,739
Undrawn commitments to extend credit
Other Commitments [Line Items]
Commitment amount	72,743	69,553
Letters of credit
Other Commitments [Line Items]
Commitment amount	2,190	2,125
Risk participation agreements
Other Commitments [Line Items]
Commitment amount	37	19
Loans sold with recourse
Other Commitments [Line Items]
Commitment amount	37	5
Marketing rights
Other Commitments [Line Items]
Commitment amount	$ 33	$ 37