The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms
Namespace Prefix:	us-gaap_
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

No definition available.

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=fitb_ExercisePriceRangeUnder15Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=fitb_Range1520Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=fitb_Range2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=fitb_Range2530Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=fitb_Range3035Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock-Based Compensation - Unvested RSUs by Grant-Date Fair Value (Details) - Restricted Stock Units - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares/Units Outstanding at Year End (in shares)	9,466	10,006	8,020	6,986
Weighted-Average Remaining Contractual Life (in years)	1 year 1 month 6 days
Under $15.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares/Units Outstanding at Year End (in shares)	51
Weighted-Average Remaining Contractual Life (in years)	1 year 7 months 6 days
$15.01-$20.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares/Units Outstanding at Year End (in shares)	249
Weighted-Average Remaining Contractual Life (in years)	4 months 24 days
$20.01-$25.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares/Units Outstanding at Year End (in shares)	259
Weighted-Average Remaining Contractual Life (in years)	1 year 2 months 12 days
$25.01-$30.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares/Units Outstanding at Year End (in shares)	7,380
Weighted-Average Remaining Contractual Life (in years)	1 year 3 months 18 days
$30.01-$35.00
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares/Units Outstanding at Year End (in shares)	1,527
Weighted-Average Remaining Contractual Life (in years)	7 months 6 days