Retirement and Benefit Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
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	$ 13
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	19
Defined Benefit Plan Expected Future Benefit Payments Year Two	18
Defined Benefit Plan Expected Future Benefit Payments Year Three	17
Defined Benefit Plan Expected Future Benefit Payments Year Four	16
Defined Benefit Plan Expected Future Benefit Payments Year Five	15
Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter	67
Accumulated benefit obligation for all defined benefit plans	256	253
Plan assets managed	185	181
Bancorp's profit sharing plan expense	17	14	11
Net underfunded status	71	72
Common Stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets managed	3	5
Fifth Third Bank Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets managed through collective funds	123	159
Deferred Profit Sharing [Member]
Defined Benefit Plan Disclosure [Line Items]
Expenses recognized for matching contributions to the Bancorp's defined contribution savings plan	42	40	36
Bancorp's profit sharing plan expense	$ 46	$ 35	$ 31