Loan Modification Program, Loans Excluded From Modification Program

No definition available.

Name:	fitb_LoanModificationProgramLoansExcludedFromModificationProgram
Namespace Prefix:	fitb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loan Modification Program, Threshold For Modification, Percent Of Total Loans And Leases

+ References

No definition available.

+ Details

Name:	fitb_LoanModificationProgramThresholdForModificationPercentOfTotalLoansAndLeases
Namespace Prefix:	fitb_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Modification Program Option, In-Process Modifications

+ References

No definition available.

+ Details

Name:	fitb_ModificationProgramOptionInProcessModifications
Namespace Prefix:	fitb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Modification Program Option, Mortgage Interest Payment Deferral, Term

+ References

No definition available.

+ Details

Name:	fitb_ModificationProgramOptionMortgageInterestPaymentDeferralTerm
Namespace Prefix:	fitb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Modification Program Option, Mortgage Term

+ References

No definition available.

+ Details

Name:	fitb_ModificationProgramOptionMortgageTerm
Namespace Prefix:	fitb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Modification Program Option, Threshold Period Past Due

+ References

No definition available.

+ Details

Name:	fitb_ModificationProgramOptionThresholdPeriodPastDue
Namespace Prefix:	fitb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Modification Program Option, Trial Period

+ References

No definition available.

+ Details

Name:	fitb_ModificationProgramOptionTrialPeriod
Namespace Prefix:	fitb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

+ Details

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

- Definition

Amortized cost excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-42

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-34

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 36
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-36

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-SubTopic 40
-Topic 310
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481746/310-40-50-1

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 35
-SubTopic 10
-Topic 310
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-35

+ Details

Name:	us-gaap_MortgageLoansInProcessOfForeclosureAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fitb_LineOfCreditReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fitb_LetterOfCreditReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Credit Quality and the Allowance for Loan and Lease Losses - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 contract	Sep. 30, 2023 USD ($)	Sep. 30, 2022 contract	Dec. 31, 2022 USD ($)
Financing Receivable, Allowance for Credit Losses
Mortgage loans in process of foreclosure amount	$ 125		$ 125		$ 154
Financing receivable, excluding accrued interest, modified in period, amount	$ 171		$ 484
Loan modification program, threshold for modification, percent of total loans and leases	0.0014		0.0040
Loan modification program, loans excluded from modification program	$ 6		$ 24
Unfunded commitment amounts	156		$ 156
Modification program option, threshold period past due			90 days
Number of Contracts \| contract		203		563
Line Of Credit Receivable
Financing Receivable, Allowance for Credit Losses
Unfunded commitment amounts					130
Letter Of Credit Receivable
Financing Receivable, Allowance for Credit Losses
Unfunded commitment amounts					$ 60
Commercial
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	124		$ 355
Commercial \| Minimum
Financing Receivable, Allowance for Credit Losses
Modification program option, mortgage interest payment deferral, term			3 months
Commercial \| Maximum
Financing Receivable, Allowance for Credit Losses
Modification program option, mortgage interest payment deferral, term			12 months
Residential Mortgage
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	31		$ 89
Modification program option, mortgage term			480 months
Modification program option, in-process modifications	7		$ 7
Number of Contracts \| contract		70		176
Residential Mortgage \| Minimum
Financing Receivable, Allowance for Credit Losses
Modification program option, mortgage interest payment deferral, term			6 months
Modification program option, trial period			3 months
Residential Mortgage \| Maximum
Financing Receivable, Allowance for Credit Losses
Modification program option, mortgage interest payment deferral, term			12 months
Modification program option, trial period			4 months
Consumer
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 16		$ 40
Modification program option, mortgage term			360 months