ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Recorded Investment in Commercial Loans and Leases by Regulatory Classification Ratings (Details) (Loans and Leases, USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total	$ 90,749	$ 85,859
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total	30,356	28,667
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total	7,239	6,948
Leases
Financing Receivable, Recorded Investment [Line Items]
Total	3,875	3,780
Total commercial
Financing Receivable, Recorded Investment [Line Items]
Total	41,470	39,395
Pass | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total	28,857	27,433
Pass | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total	6,869	6,366
Pass | Leases
Financing Receivable, Recorded Investment [Line Items]
Total	3,814	3,679
Pass | Total commercial
Financing Receivable, Recorded Investment [Line Items]
Total	39,540	37,478
Special Mention | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total	861	588
Special Mention | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total	207	339
Special Mention | Leases
Financing Receivable, Recorded Investment [Line Items]
Total	15	40
Special Mention | Total commercial
Financing Receivable, Recorded Investment [Line Items]
Total	1,083	967
Substandard | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total	517	541
Substandard | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total	97	116
Substandard | Leases
Financing Receivable, Recorded Investment [Line Items]
Total	46	61
Substandard | Total commercial
Financing Receivable, Recorded Investment [Line Items]
Total	660	718
Doubtful | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total	121	105
Doubtful | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total	66	127
Doubtful | Leases
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
Doubtful | Total commercial
Financing Receivable, Recorded Investment [Line Items]
Total	$ 187	$ 232