Name:	cfg_CommitmentsAbstract
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Name:	cfg_ConsumerProductsAbstract
Namespace Prefix:	cfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow for indemnification payment requests during the period.

+ References

No definition available.

+ Details

Name:	cfg_IndemnificationPaymentRequestsAmountPaid
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of indemnification payment requests received during the period.

+ References

No definition available.

+ Details

Name:	cfg_IndemnificationPaymentRequestsReceivedAmount
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	cfg_LettersofCreditAbstract
Namespace Prefix:	cfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of restitution awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

Name:	cfg_LitigationSettlementRestitutionAmount
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The repurchase of loans that are secured with real estate mortgages per the terms of the original mortgage sale to government-sponsored entities and other parties.

+ References

No definition available.

+ Details

Name:	cfg_MortgageLoansRepurchased
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	cfg_MortgageRepurchaseDemandsAbstract
Namespace Prefix:	cfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of mortgage repurchase demands received during the period.

+ References

No definition available.

+ Details

Name:	cfg_MortgageRepurchaseDemandsReceivedAmount
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow for mortgage repurchase demands paid during the period.

+ References

No definition available.

+ Details

Name:	cfg_PaymentsforRepurchaseofMortgageLoans
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow for acquisition of naming rights during the period.

+ References

No definition available.

+ Details

Name:	cfg_PaymentstoAcquireStadiumNamingRights
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Minimum amount of purchase arrangement maturing in the second fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

+ References

No definition available.

+ Details

Name:	cfg_PurchaseObligationDueafterNextTwelveMonths
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of credit exposure pertaining to risk participation agreements.

+ References

No definition available.

+ Details

Name:	cfg_RiskParticipationAgreements
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	cfg_RiskParticipationAgreementsAbstract
Namespace Prefix:	cfg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Average period covered by risk participation contracts in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	cfg_RiskParticipationAgreementsAverageTerm
Namespace Prefix:	cfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of risk participation agreement counterparties.

+ References

No definition available.

+ Details

Name:	cfg_RiskParticipationAgreementsCounterpartiesNumber
Namespace Prefix:	cfg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum period covered by risk participation contracts in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	cfg_RiskParticipationAgreementsMaximumTerm
Namespace Prefix:	cfg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The total remaining amount of the contingent obligation under naming rights agreement outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	cfg_StadiumNamingRightsRemainingObligationDue
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The face amount of commercial and commercial real estate loans committed to purchase, but unsettled as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	cfg_UnsettledReceivableHeldForSaleAmount
Namespace Prefix:	cfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_GuaranteesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Period covered by the long-term purchase commitment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermPurchaseCommitmentPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LitigationCaseAxis=cfg_ConsentOrdersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=cfg_NamingRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=cfg_StudentLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=us-gaap_AutomobileLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_CreditRiskContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_NetAmountAtRiskByProductAndGuaranteeGuaranteeTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PurchaseCommitmentExcludingLongtermCommitmentAxis=us-gaap_PurchaseCommitmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
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Period Type:

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Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
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Period Type:

COMMITMENTS AND CONTINGENCIES - Narrative (Details) (USD $)	12 Months Ended			72 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2014 counterparty	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Apr. 30, 2013	Dec. 31, 2003	May 29, 2014
Risk Participation Agreements [Abstract]
Risk participation agreements	$ 19,000,000cfg_RiskParticipationAgreements	$ 17,000,000cfg_RiskParticipationAgreements		$ 19,000,000cfg_RiskParticipationAgreements
Risk participation agreements number of counterparties	71
Risk participation agreements, Maximum term	11 years
Mortgage Repurchase Demands [Abstract]
Mortgage repurchase demands received				158,000,000
Indemnification payment requests received				99,000,000
Repurchased mortgage loans	25,000,000cfg_MortgageLoansRepurchased	35,000,000cfg_MortgageLoansRepurchased	13,000,000cfg_MortgageLoansRepurchased	88,000,000cfg_MortgageLoansRepurchased
Indemnification payment requests paid	8,000,000	12,000,000		33,000,000
Payments for Repurchase of Mortgage Loans	25,000,000	35,000,000
Consent Orders
Consumer Products [Abstract]
Litigation settlement amount					10,000,000
Restitution amount payable	8,000,000			8,000,000
Minimum
Risk Participation Agreements [Abstract]
Risk participation agreements, Average term	1 year
Maximum
Risk Participation Agreements [Abstract]
Risk participation agreements, Average term	5 years
Letter of Credit
Letters of Credit [Abstract]
Letters of credit outstanding	3,000,000			3,000,000
Auto Loans \| Minimum
Commitments [Abstract]
Purchase commitment, Quarterly amount, May 30, 2014 through May 29, 2015							250,000,000
Purchase commitment, Quarterly amount, May 30, 2015 and after							400,000,000
Auto Loans \| Maximum
Commitments [Abstract]
Purchase commitment, Quarterly amount, May 30, 2014 through May 29, 2015							600,000,000
Purchase commitment, Quarterly amount, May 30, 2015 and after							600,000,000
Student loans \| Minimum
Commitments [Abstract]
Purchase commitment, Quarterly amount, May 30, 2014 through May 29, 2015	260,000,000			260,000,000
Marketing rights
Commitments [Abstract]
Commitment period						25 years
Payments made	3,000,000	3,000,000
Remaining obligation due	51,000,000			51,000,000
Derivative assets - credit default swaps \| RBS \| Options Held
Guarantees [Abstract]
Notional value of open option contracts	0	2,000,000		0
Purchase Commitment \| Commercial real estate loans held for sale
Commitments [Abstract]
Unsettled commercial loan trades	$ 40,000,000			$ 40,000,000