RELATED PARTY TRANSACTIONS AND SIGNIFICANT TRANSACTIONS WITH RBS - Schedule of Related Party Debt Terms (Details) - USD ($) $ in Millions		Mar. 07, 2016	Mar. 31, 2016		Dec. 31, 2015
Related Party Transaction [Line Items]
Long-term borrowed funds			$ 10,035		$ 9,886
Citizens Financial Group, Inc.
Related Party Transaction [Line Items]
Long-term borrowed funds			$ 2,487
Subordinated Debt | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023 | Citizens Financial Group, Inc.
Related Party Transaction [Line Items]
Interest rate	[1]		5.158%
Long-term borrowed funds	[1]		$ 333		$ 333
Subordinated Debt | 3.750% fixed rate subordinated debt due 2024 | Citizens Financial Group, Inc.
Related Party Transaction [Line Items]
Interest rate	[1]		3.75%	[2]	4.153%
Long-term borrowed funds	[1],[2]		$ 250		$ 250
Subordinated Debt | 4.023% fixed rate subordinated debt, due 2024 | Citizens Financial Group, Inc.
Related Party Transaction [Line Items]
Interest rate	[1],[3]		4.023%
Long-term borrowed funds	[1],[3]		$ 214		331
Extinguishment of debt, amount		$ 125
Subordinated Debt | 4.082% fixed rate subordinated debt, due 2025 | Citizens Financial Group, Inc.
Related Party Transaction [Line Items]
Interest rate	[1],[4]		4.082%
Long-term borrowed funds	[1],[4]		$ 346		331
RBSG
Related Party Transaction [Line Items]
Long-term borrowed funds			$ 1,125		$ 1,250
RBSG | Subordinated Debt | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023
Related Party Transaction [Line Items]
Interest rate			5.158%		5.158%
Long-term borrowed funds			$ 333		$ 333
RBSG | Subordinated Debt | 3.750% fixed rate subordinated debt due 2024
Related Party Transaction [Line Items]
Interest rate			3.75%	[5]	4.153%
Long-term borrowed funds			$ 250		$ 250
RBSG | Subordinated Debt | 4.023% fixed rate subordinated debt, due 2024
Related Party Transaction [Line Items]
Interest rate			4.023%	[6]	4.023%
Long-term borrowed funds			$ 208		$ 333
RBSG | Subordinated Debt | 4.082% fixed rate subordinated debt, due 2025
Related Party Transaction [Line Items]
Interest rate			4.082%		4.082%
Long-term borrowed funds			$ 334		$ 334

[1] Borrowed funds with RBS. See Note 13 “Related Party Transactions and Significant Transactions with RBS” for further information.

[2] Prior to January 1, 2016, interest was payable at a fixed rate per annum of 4.153%.

[3] These balances are comprised of: principal balance of $208 million and $333 million at March 31, 2016 and December 31, 2015, respectively, as well as the impact from interest rate swaps of $6 million and ($2) million at March 31, 2016 and December 31, 2015, respectively. See Note 11 “Derivatives” for further information. In addition, on March 7, 2016, the Company repurchased $125 million of these securities from RBS. See Note 13 “Related Party Transactions and Significant Transactions with RBS” for further information.

[4] These balances are comprised of: principal balance of $334 million at March 31, 2016 and December 31, 2015; impact from interest rate swaps of $12 million and ($3) million at March 31, 2016 and December 31, 2015, respectively. See Note 11 “Derivatives” for further information.

[5] Prior to January 1, 2016, interest was payable at a fixed rate per annum of 4.153%.

[6] On March 7, 2016, the Company repurchased $125 million of these securities from RBS.