Summary of Significant Accounting and Reporting Policies - Impaired Loans and Leases (Details) $ in Millions	Dec. 31, 2021 USD ($)
Accounting Policies [Abstract]
Impaired financing receivable on accrual status, threshold amount	$ 1

Impaired Financing Receivable, Excluding Accrued Interest, Threshold Amount

No definition available.

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