ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Loans with Indicators of High Credit Risk (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
High loan-to-value
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	$ 4,321	$ 5,433
High loan-to-value | Residential Mortgages
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	847	1,054
High loan-to-value | Home Equity Loans and Lines of Credit
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	2,183	2,798
High loan-to-value | Home equity products serviced by others
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	1,291	1,581
High loan-to-value | Credit Cards
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Interest only/negative amortization
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	863	882
Interest only/negative amortization | Residential Mortgages
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	863	882
Interest only/negative amortization | Home Equity Loans and Lines of Credit
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Interest only/negative amortization | Home equity products serviced by others
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Interest only/negative amortization | Credit Cards
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Low introductory rate
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	100	119
Low introductory rate | Residential Mortgages
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Low introductory rate | Home Equity Loans and Lines of Credit
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Low introductory rate | Home equity products serviced by others
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Low introductory rate | Credit Cards
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	100	119
Multiple characteristics and other
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	56	96
Multiple characteristics and other | Residential Mortgages
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	56	96
Multiple characteristics and other | Home Equity Loans and Lines of Credit
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Multiple characteristics and other | Home equity products serviced by others
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Multiple characteristics and other | Credit Cards
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	0	0
Credit Risk, Loan Products with Increased Credit Exposure [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	5,340	6,530
Credit Risk, Loan Products with Increased Credit Exposure [Member] | Residential Mortgages
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	1,766	2,032
Credit Risk, Loan Products with Increased Credit Exposure [Member] | Home Equity Loans and Lines of Credit
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	2,183	2,798
Credit Risk, Loan Products with Increased Credit Exposure [Member] | Home equity products serviced by others
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	1,291	1,581
Credit Risk, Loan Products with Increased Credit Exposure [Member] | Credit Cards
Financing Receivable, Recorded Investment [Line Items]
Credit risk indicated, Loan balance	$ 100	$ 119