COMMITMENTS AND CONTINGENCIES - Schedule of Outstanding Off-balance sheet Arrangements (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Other Commitments [Line Items]
Commitment amount	$ 64,220	$ 62,918
Undrawn commitments to extend credit
Other Commitments [Line Items]
Commitment amount	61,988	60,872
Financial standby letters of credit
Other Commitments [Line Items]
Commitment amount	2,053	1,892
Performance letters of credit
Other Commitments [Line Items]
Commitment amount	41	40
Commercial letters of credit
Other Commitments [Line Items]
Commitment amount	66	43
Marketing rights
Other Commitments [Line Items]
Commitment amount	42	44
Risk participation agreements
Other Commitments [Line Items]
Commitment amount	22	19
Residential mortgage loans sold with recourse
Other Commitments [Line Items]
Commitment amount	$ 8	$ 8