RELATED PARTY TRANSACTIONS - Schedule of Related Party Debt Terms (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Long-term borrowed funds	$ 2,062	$ 1,405
Subordinated Debt | RBSG | 4.023% fixed rate subordinated debt, due 2024
Related Party Transaction [Line Items]
Interest rate	4.023%
Long-term borrowed funds	333	0
Subordinated Debt | RBSG | 4.153% fixed rate subordinated debt due 2024
Related Party Transaction [Line Items]
Interest rate	4.153%
Long-term borrowed funds	333	0
Subordinated Debt | RBSG | 4.691% fixed rate subordinated debt, due 2024
Related Party Transaction [Line Items]
Interest rate	4.691%
Long-term borrowed funds	334	334
Subordinated Debt | RBSG | 4.771% fixed rate subordinated debt, due 2023
Related Party Transaction [Line Items]
Interest rate	4.771%
Long-term borrowed funds	333	333
Subordinated Debt | RBS | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023
Related Party Transaction [Line Items]
Interest rate	5.158%
Long-term borrowed funds	$ 333	$ 333