COMMITMENTS AND CONTINGENCIES - Schedule of Outstanding Off-balance sheet Arrangements (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Other Commitments [Line Items]
Commitment amount	$ 58,746	$ 58,435
Undrawn commitments to extend credit
Other Commitments [Line Items]
Commitment amount	56,524	55,899
Financial standby letters of credit
Other Commitments [Line Items]
Commitment amount	2,010	2,315
Performance letters of credit
Other Commitments [Line Items]
Commitment amount	42	65
Commercial letters of credit
Other Commitments [Line Items]
Commitment amount	87	75
Marketing rights
Other Commitments [Line Items]
Commitment amount	47	51
Risk participation agreements
Other Commitments [Line Items]
Commitment amount	26	19
Residential mortgage loans sold with recourse
Other Commitments [Line Items]
Commitment amount	$ 10	$ 11