Troubled Debt Restructuring Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Troubled Debt Restructuring
Letter of credit commitments for modified troubled debt restructurings	$ 40	$ 25

Letter of credit commitments for modified troubled debt restructurings

No definition available.

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