Summary of the Bancorp's Unrecognized Tax Benefits (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Income Tax Contingency [Line Items]
Tax positions that would impact the effective tax rate, if recognized	$ 14	$ 15
Tax positions where the ultimate deductibility is highly certain, but for which there is uncertainty about the timing of the deduction		1
Unrecognized tax benefits	$ 14	$ 16	$ 82	$ 959