BORROWED FUNDS - Long Term Debt (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term borrowed funds	$ 2,062	$ 1,405
Citizens Financial Group, Inc.: | Subordinated Debt | 4.150% fixed rate subordinated debt, due 2022
Debt Instrument [Line Items]
Long-term borrowed funds	350	350
Interest rate	4.15%
Maturity date	Jan. 01, 2022
Citizens Financial Group, Inc.: | Subordinated Debt | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023
Debt Instrument [Line Items]
Long-term borrowed funds	333	333
Interest rate	5.158%
Maturity date	Jun. 30, 2023
Citizens Financial Group, Inc.: | Subordinated Debt | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023 | LIBOR
Debt Instrument [Line Items]
Interest rate	3.56%
Citizens Financial Group, Inc.: | Subordinated Debt | 4.771% fixed rate subordinated debt, due 2023
Debt Instrument [Line Items]
Long-term borrowed funds	333	333
Interest rate	4.771%
Maturity date	Oct. 31, 2023
Citizens Financial Group, Inc.: | Subordinated Debt | 4.691% fixed rate subordinated debt, due 2024
Debt Instrument [Line Items]
Long-term borrowed funds	334	334
Interest rate	4.691%
Maturity date	Jan. 31, 2024
Citizens Financial Group, Inc.: | Subordinated Debt | 4.153% fixed rate subordinated debt due 2024
Debt Instrument [Line Items]
Long-term borrowed funds	333	0
Interest rate	4.153%
Maturity date	Jul. 31, 2024
Citizens Financial Group, Inc.: | Subordinated Debt | 4.023% fixed rate subordinated debt, due 2024
Debt Instrument [Line Items]
Long-term borrowed funds	333	0
Interest rate	4.023%
Maturity date	Oct. 31, 2024
Banking Subsidiaries: | Federal Home Loan advances due through 2033
Debt Instrument [Line Items]
Long-term borrowed funds	23	25
Maturity date	Jan. 01, 2033
Banking Subsidiaries: | Other
Debt Instrument [Line Items]
Long-term borrowed funds	$ 23	$ 30