ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Other Nonperforming Assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonperforming assets, net of valuation allowance	$ 42	$ 50
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonperforming assets, net of valuation allowance	3	10
Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonperforming assets, net of valuation allowance	$ 39	$ 40