RELATED PARTY TRANSACTIONS - Schedule of Related Party Transactions Effect on Net Interest Income (Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Related Party Transactions Effect on Net Interest Income (Expense) [Line Items]
Interest expense	$ (19)	$ (17)	$ (59)	$ (42)
RBS | Interest rate swaps
Schedule of Related Party Transactions Effect on Net Interest Income (Expense) [Line Items]
Interest income	$ 3		$ 9
Interest expense		$ (1)		$ (22)