Results of Operations and Average Assets by Segment (Parenthetical) (Detail) (Branch Banking, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Branch Banking
Segment Reporting Information [Line Items]
Bank Premises Impairment	$ 20	$ 6	$ 21

Lower of cost or market adjustments and the aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

No definition available.

Name:	fitb_ImpairmentOfRealEstate1
Namespace Prefix:	fitb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration