Retirement and Benefit Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
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	$ 14
The increase in pension expense by lowering both the expected rate of return on the plan and the discount rate by 0.25%	1
Estimated pension benefit payments for expected future service in year one	20
Estimated pension benefit payments for expected future service in year two	17
Estimated pension benefit payments for expected future service in year three	16
Estimated pension benefit payments for expected future service in year four	16
Estimated pension benefit payments for expected future service in year five	15
Total estimated payments in five fiscal years thereafter	66
Expenses recognized for matching contributions to the Bancorp's defined contribution savings plan	40	36	36
Accumulated benefit obligation for all defined benefit plans	253	227
Plan assets managed	181	197
Bancorp's profit sharing plan expense	14	11	29
Fifth Third Bank Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets managed through mutual funds	159	172
Fifth Third Bank Ohio [Member] | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets managed	5	5
Deferred Profit Sharing [Member]
Defined Benefit Plan Disclosure [Line Items]
Bancorp's profit sharing plan expense	$ 35	$ 31	$ 17