Regulatory Capital Requirements and Capital Ratios (Details) $ in Millions	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fifth Third Bancorp
Risk Based Ratios
CET1 capital (as a percent)	0.1034	0.0975
Tier I risk-based capital (as a percent)	0.1183	0.1099
Total risk-based capital (as a percent)	0.1508	0.1384
Tier I leverage (as a percent)	0.0849	0.0954
Risk Based Capital
CET1 capital	$ 14,682	$ 13,847
Tier I risk-based capital	16,797	15,616
Total risk-based capital	21,412	19,661
Tier I leverage	$ 16,797	$ 15,616
Fifth Third Bancorp | Well-Capitalized
Risk Based Ratios
Tier I risk-based capital (as a percent)	0.0600
Total risk-based capital (as a percent)	0.1000
Fifth Third Bancorp | Minimum
Risk Based Ratios
CET1 capital (as a percent)	0.0450
Tier I risk-based capital (as a percent)	0.0600
Total risk-based capital (as a percent)	0.0800
Tier I leverage (as a percent)	0.0400
Fifth Third Bank, National Association
Risk Based Ratios
CET1 capital (as a percent)	0.1228	0.1186
Tier I risk-based capital (as a percent)	0.1228	0.1186
Total risk-based capital (as a percent)	0.1417	0.1346
Tier I leverage (as a percent)	0.0885	0.1036
Risk Based Capital
CET1 capital	$ 17,253	$ 16,704
Tier I risk-based capital	17,253	16,704
Total risk-based capital	19,915	18,968
Tier I leverage	$ 17,253	$ 16,704
Fifth Third Bank, National Association | Well-Capitalized
Risk Based Ratios
CET1 capital (as a percent)	0.0650
Tier I risk-based capital (as a percent)	0.0800
Total risk-based capital (as a percent)	0.1000
Tier I leverage (as a percent)	0.0500
Fifth Third Bank, National Association | Minimum
Risk Based Ratios
CET1 capital (as a percent)	0.0450
Tier I risk-based capital (as a percent)	0.0600
Total risk-based capital (as a percent)	0.0800
Tier I leverage (as a percent)	0.0400