Summary of Significant Accounting and Reporting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Significant Accounting Policies [Line Items]
Established threshold	$ 1
Lower Limit [Member]
Significant Accounting Policies [Line Items]
Larger commercial loans, subject to impairment review	1
Established threshold nonaccrual commercial loans	$ 1

Reflects the adjusted carrying amount of loans for which it is probable, based on current facts and circumstances, that a creditor will not initially be able to collect all amounts due according to the contractual terms of the loan agreement, or will not recover the previously reported carrying amount of the loan.

No definition available.

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