Outstanding and Exercisable Stock Options by Exercise Price (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	265
Weighted-Average Remaining Contractual Life	1 year
Weighted-Average Exercise Price	$ 14.25
Under $10.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	1
Weighted-Average Remaining Contractual Life	4 years
Weighted-Average Exercise Price	$ 8.59
$10.01-$20.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	258
Weighted-Average Remaining Contractual Life	1 year
Weighted-Average Exercise Price	$ 13.76
$20.01-$30.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	1
Weighted-Average Remaining Contractual Life	3 years
Weighted-Average Exercise Price	$ 24.41
Over $40.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options at Year End	5
Weighted-Average Remaining Contractual Life	2 years
Weighted-Average Exercise Price	$ 40.98

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

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Details

Name:	fitb_GrantPriceRangeAxis=fitb_Range1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fitb_GrantPriceRangeAxis=fitb_Range2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fitb_GrantPriceRangeAxis=fitb_Range3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fitb_GrantPriceRangeAxis=fitb_Range5Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: