Retirement and Benefit Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
The estimated net actuarial loss for the defined benefit pension plans that will be amortized from accumulated other comprehensive income into net periodic benefit cost	$ 10
The increase in pension expense by lowering both the expected rate of return on the plan and the discount rate by 0.25%	1
Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months	22
Defined Benefit Plan Expected Future Benefit Payments Year Two	21
Defined Benefit Plan Expected Future Benefit Payments Year Three	19
Defined Benefit Plan Expected Future Benefit Payments Year Four	18
Defined Benefit Plan Expected Future Benefit Payments Year Five	16
Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter	80
Estimated future defined benefit plan contributions	4
Accumulated benefit obligation for all defined benefit plans	247		221
Plan assets managed	195	[1]	200	[1]
Profit sharing plan expense	334		357		371
Net underfunded status	(52)		(21)
Change in mortality assumption
Defined Benefit Plan Disclosure [Line Items]
Mortality assumption PBO increase	14
Deferred Profit Sharing
Defined Benefit Plan Disclosure [Line Items]
Expenses recognized for matching contributions to the Bancorp's defined contribution savings plan	44		43		42
Profit sharing plan expense	19		32		46
Common Stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets managed	4		4
Fifth Third Bank Ohio
Defined Benefit Plan Disclosure [Line Items]
Plan assets managed through collective funds	$ 195		$ 200

[1] For further information on fair value hierarchy levels, refer to Note 1.