BORROWED FUNDS - Long Term Debt (Details) - USD ($) $ in Millions		Dec. 31, 2015	Aug. 03, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term borrowed funds		$ 9,886		$ 4,642
Interest rate swaps		807		790
Interest rate swaps
Debt Instrument [Line Items]
Interest rate swaps		636		613
Citizens Financial Group, Inc.
Debt Instrument [Line Items]
Long-term borrowed funds		2,595
Banking Subsidiaries
Debt Instrument [Line Items]
Long-term borrowed funds		$ 7,291
Subordinated Debt | 4.350% fixed rate subordinated debt, due 2025
Debt Instrument [Line Items]
Interest rate			4.35%
Subordinated Debt | Citizens Financial Group, Inc. | 4.150% fixed rate subordinated debt, due 2022
Debt Instrument [Line Items]
Interest rate		4.15%
Long-term borrowed funds		$ 350		350
Subordinated Debt | Citizens Financial Group, Inc. | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023
Debt Instrument [Line Items]
Interest rate	[1]	5.158%
Long-term borrowed funds	[1]	$ 333		333
Subordinated Debt | Citizens Financial Group, Inc. | 4.771% fixed rate subordinated debt, due 2023
Debt Instrument [Line Items]
Interest rate	[1]	4.771%
Long-term borrowed funds	[1]	$ 0		333
Subordinated Debt | Citizens Financial Group, Inc. | 4.691% fixed rate subordinated debt, due 2024
Debt Instrument [Line Items]
Interest rate	[1]	4.691%
Long-term borrowed funds	[1]	$ 0		334
Subordinated Debt | Citizens Financial Group, Inc. | 4.153% fixed rate subordinated debt due 2024
Debt Instrument [Line Items]
Interest rate	[1],[2]	4.153%
Long-term borrowed funds	[1],[2]	$ 250		333
Subordinated Debt | Citizens Financial Group, Inc. | 3.750% fixed rate subordinated debt due 2024
Debt Instrument [Line Items]
Interest rate	[1],[2]	3.75%
Subordinated Debt | Citizens Financial Group, Inc. | 4.023% fixed rate subordinated debt, due 2024
Debt Instrument [Line Items]
Interest rate	[1],[3]	4.023%
Long-term borrowed funds	[1],[3]	$ 331		333
Unsecured debt	[1]	$ 333
Subordinated Debt | Citizens Financial Group, Inc. | 4.082% fixed rate subordinated debt, due 2025
Debt Instrument [Line Items]
Interest rate	[1],[4]	4.082%
Long-term borrowed funds	[1],[4]	$ 331		334
Unsecured debt	[1]	$ 334
Subordinated Debt | Citizens Financial Group, Inc. | 4.350% fixed rate subordinated debt, due 2025
Debt Instrument [Line Items]
Interest rate		4.35%
Long-term borrowed funds		$ 250		0
Subordinated Debt | Citizens Financial Group, Inc. | 4.300% fixed rate subordinated debt, due 2025
Debt Instrument [Line Items]
Interest rate		4.30%
Long-term borrowed funds		$ 750		0
Subordinated Debt | Citizens Financial Group, Inc. | LIBOR | 5.158% fixed-to-floating rate subordinated debt, (LIBOR 3.56%) callable, due 2023
Debt Instrument [Line Items]
Interest rate	[1]	3.56%
Senior Unsecured Notes | Interest rate swaps | 4.023% fixed rate subordinated debt, due 2024
Debt Instrument [Line Items]
Interest rate swaps	[1]	$ 2
Senior Unsecured Notes | Interest rate swaps | 4.082% fixed rate subordinated debt, due 2025
Debt Instrument [Line Items]
Interest rate swaps	[1]	3
Senior Unsecured Notes | Interest rate swaps | 1.600% senior unsecured notes, due 2017
Debt Instrument [Line Items]
Interest rate swaps	[5]	1
Senior Unsecured Notes | Interest rate swaps | 2.300% senior unsecured notes, due 2018
Debt Instrument [Line Items]
Interest rate swaps	[5]	3
Senior Unsecured Notes | Interest rate swaps | 2.450% senior unsecured notes, due 2019
Debt Instrument [Line Items]
Interest rate swaps	[5]	$ 2
Senior Unsecured Notes | Banking Subsidiaries | 1.600% senior unsecured notes, due 2017
Debt Instrument [Line Items]
Interest rate	[5],[6]	1.60%
Long-term borrowed funds	[5],[6]	$ 749		750
Unsecured debt	[5]	$ 750
Senior Unsecured Notes | Banking Subsidiaries | 2.300% senior unsecured notes, due 2018
Debt Instrument [Line Items]
Interest rate	[5],[7]	2.30%
Long-term borrowed funds	[5],[7]	$ 747		0
Unsecured debt	[5]	$ 750
Senior Unsecured Notes | Banking Subsidiaries | 2.450% senior unsecured notes, due 2019
Debt Instrument [Line Items]
Interest rate	[5],[8]	2.45%
Long-term borrowed funds	[5],[8]	$ 752		746
Unsecured debt	[5]	750
Federal Home Loan advances | Banking Subsidiaries
Debt Instrument [Line Items]
Long-term borrowed funds		5,018		772
Other | Banking Subsidiaries
Debt Instrument [Line Items]
Long-term borrowed funds		$ 25		$ 24

[1] Borrowed funds with RBS. See Note 19 “Related Party Transactions and Significant Transactions with RBS” for further information.

[2] Interest is payable until January 1, 2016 at a fixed rate per annum of 4.153% and at a fixed rate per annum of 3.750% thereafter.

[3] $333 million principal balance of subordinated debt reflects the impact of $2 million hedge of interest rate risk on medium term debt using interest rate swaps at December 31, 2015. See Note 16 “Derivatives” for further information.

[4] $334 million principal balance of subordinated debt reflects the impact of $3 million hedge of interest rate risk on medium term debt using interest rate swaps at December 31, 2015. See Note 16 “Derivatives” for further information.

[5] These securities were offered under CBNA’s Global Bank Note Program dated December 1, 2014.

[6] $750 million principal balance of unsecured notes reflects the impact of $1 million hedge of interest rate risk on medium term debt using interest rate swaps at December 31, 2015. See Note 16 “Derivatives” for further information.

[7] $750 million principal balance of unsecured notes reflects the impact of $3 million hedge of interest rate risk on medium term debt using interest rate swaps at December 31, 2015. See Note 16 “Derivatives” for further information.

[8] $750 million principal balance of unsecured notes reflects the impact of $2 million hedge of interest rate risk on medium term debt using interest rate swaps at December 31, 2015. See Note 16 “Derivatives” for further information.