Loans and Leases - Components of Net Investment in Leases (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Net investment in sales-type leases:
Leveraged leases	$ 366	$ 429
Direct Financing Leases
Net investment in direct financing leases:
Lease payment receivable (present value)	1,610	2,196
Unguaranteed residual assets (present value)	198	220
Net discount on acquired leases	0	(7)
Sales-Type Leases
Net investment in sales-type leases:
Lease payment receivable (present value)	818	510
Unguaranteed residual assets (present value)	$ 29	$ 15

Direct Financing Lease, Net Discount On Acquired Leases

No definition available.

Name:	fitb_DirectFinancingLeaseNetDiscountOnAcquiredLeases
Namespace Prefix:	fitb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term, guaranteed by lessee or other third party unrelated to lessor, from direct financing lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919379-209981

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Present value expected to be derived from underlying asset, following end of lease term, not guaranteed by lessee or other third party unrelated to lessor.

+ References

+ Details

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

- Definition

The net investment in arrangements meeting the criteria to be classified as leveraged.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 50
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121579104&loc=SL77920254-209983

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121555262&loc=d3e45152-112736

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121602638&loc=SL77920237-209979

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121568338&loc=d3e45424-112738

+ Details

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

- Definition

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type lease.

+ References

+ Details

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

- Definition

Present value expected to be derived from underlying asset following end of lease term not guaranteed by lessee or other third party unrelated to lessor.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_FinanceLeasesPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=fitb_SalesTypeLeasesPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: