ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Nonperforming Loans and Leases by Class (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	$ 1,071	$ 1,383
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	8	33
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	1,079	1,416
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	93	96
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	0	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	93	96
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	82	169
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	1	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	83	169
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	0	0
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	0	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	0	0
Total commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	175	265
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	1	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	176	265
Residential, including originated home equity products
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	770	981
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	0	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	770	981
Home equity products serviced by others
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	81	89
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	0	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	81	89
Other secured retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	22	26
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	0	0
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	22	26
Unsecured retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	23	22
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	7	33
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	30	55
Total retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccruing	896	1,118
Financing Receivable, Recorded Investment, Accruing and 90 Days or More Delinquent	7	33
Financing Receivable, Recorded Investment, Total Nonperforming Loans and Leases	$ 903	$ 1,151