Regulatory Capital Requirements (Capital and Risk-Based Capital and Leverage Ratios for the Bancorp and its Significant Subsidiary Banks) (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fifth Third Bancorp
Risk Based Ratios
CET1 capital ratio (to risk-weighted assets)	10.24%	10.61%
Tier I risk-based capital (to risk-weighted assets)	11.32%	11.74%
Total risk-based capital (to risk-weighted assets)	14.48%	15.16%
Tier I leverage (to quarterly average assets)	9.72%	10.01%
Risk Based Capital
CET1 capital (to risk-weighted assets)	$ 12,534	$ 12,517
Tier I risk-based capital (to risk-weighted assets)	13,864	13,848
Total risk-based capital (to risk weighted assets)	17,723	17,887
Tier I leverage (to quarterly average assets)	$ 13,864	$ 13,848
Fifth Third Bank
Risk Based Ratios
CET1 capital ratio (to risk-weighted assets)	11.93%	12.06%
Tier I risk-based capital (to risk-weighted assets)	11.93%	12.06%
Total risk-based capital (to risk-weighted assets)	13.57%	13.88%
Tier I leverage (to quarterly average assets)	10.27%	10.32%
Risk Based Capital
CET1 capital (to risk-weighted assets)	$ 14,435	$ 14,008
Tier I risk-based capital (to risk-weighted assets)	14,435	14,008
Total risk-based capital (to risk weighted assets)	16,427	16,126
Tier I leverage (to quarterly average assets)	$ 14,435	$ 14,008
Minimum
Risk Based Ratios
CET1 capital ratio (to risk-weighted assets)	4.50%
Tier I risk-based capital (to risk-weighted assets)	6.00%
Total risk-based capital (to risk-weighted assets)	8.00%
Tier I leverage (to quarterly average assets)	4.00%
Well-capitalized
Risk Based Ratios
CET1 capital ratio (to risk-weighted assets)	6.50%
Tier I risk-based capital (to risk-weighted assets)	8.00%
Total risk-based capital (to risk-weighted assets)	10.00%
Tier I leverage (to quarterly average assets)	5.00%