COMMITMENTS AND CONTINGENCIES - Schedule of Outstanding Off-balance sheet Arrangements (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Other Commitments [Line Items]
Commitment amount	$ 64,884	$ 62,918
Undrawn commitments to extend credit
Other Commitments [Line Items]
Commitment amount	62,810	60,872
Financial standby letters of credit
Other Commitments [Line Items]
Commitment amount	1,912	1,892
Performance letters of credit
Other Commitments [Line Items]
Commitment amount	48	40
Commercial letters of credit
Other Commitments [Line Items]
Commitment amount	43	43
Marketing rights
Other Commitments [Line Items]
Commitment amount	44	44
Risk participation agreements
Other Commitments [Line Items]
Commitment amount	19	19
Residential mortgage loans sold with recourse
Other Commitments [Line Items]
Commitment amount	$ 8	$ 8