Subsequent Event - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2016 USD ($)
Subsequent Event
Gain On Branch Consolidation And Sales Plan	$ 8
Subsequent events \| Pittsburgh Sale to First National Bank of Pennsylvania
Subsequent Event
Gain On Branch Consolidation And Sales Plan	$ 11
Subsequent Events Date	Apr. 22, 2016
Loans Sold	$ 99
Deposits Sold	302
Premises And Equipment Sold	$ 16

Amount classified as deposits disposed of

No definition available.

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

- Definition

Gain included in earnings related to the Branch Consolidation and Sales Plan

+ References

No definition available.

+ Details

Name:	fitb_GainOnBranchConsolidationAndSalesPlan
Namespace Prefix:	fitb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amounts classified as loans disposed of

+ References

No definition available.

+ Details

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

- Definition

Amount classified as bank premises and equipment disposed of

+ References

No definition available.

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Definition

Date the event occurred after the balance sheet date but before financial statements are issues or available to be issued, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=fitb_PittsburghtOfFirstNationalBankOfPennsylvaniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: