VIE (Assets and Liabilities Related to Non-consolidated VIEs and Maximum Exposure to Losses) (Detail) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fifth Third Community Development Corporation Investments
Variable Interest Entity
Total Assets	$ 1,431	$ 1,421
Total Liabilities	382	357
Maximum Exposure	1,431	1,421
Private Equity Investments
Variable Interest Entity
Total Assets	106	176
Total Liabilities	0	0
Maximum Exposure	158	232
Loans Provided to VIEs
Variable Interest Entity
Total Assets	1,914	1,735
Total Liabilities	0	0
Maximum Exposure	$ 2,923	$ 2,672

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=77990344&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=77990344&loc=d3e5747-111685

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

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- Definition

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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- Details

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- Details

Name:	us-gaap_FinancialInstrumentAxis=fitb_FifthThirdCommunityDevelopmentCorporationInvestmentsMember
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- Details

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- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_LoansReceivableMember
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