COMMITMENTS AND CONTINGENCIES - Schedule of Outstanding Off-balance sheet Arrangements (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Other Commitments [Line Items]
Commitment amount	$ 59,124	$ 58,746
Undrawn commitments to extend credit
Other Commitments [Line Items]
Commitment amount	56,989	56,524
Financial standby letters of credit
Other Commitments [Line Items]
Commitment amount	1,921	2,010
Performance letters of credit
Other Commitments [Line Items]
Commitment amount	41	42
Commercial letters of credit
Other Commitments [Line Items]
Commitment amount	63	87
Marketing rights
Other Commitments [Line Items]
Commitment amount	47	47
Risk participation agreements
Other Commitments [Line Items]
Commitment amount	53	26
Residential mortgage loans sold with recourse
Other Commitments [Line Items]
Commitment amount	$ 10	$ 10