Investments in Qualified Affordable Housing Tax Credits (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Other noninterest expense
Investments In Affordable Housing Projects [Line Items]
Pre-tax investment losses	$ 34		$ 29
Impairment losses	33	[1]	29	[1]
Applicable income tax expense
Investments In Affordable Housing Projects [Line Items]
Tax credits and other benefits	$ 52		$ 47

[1] The Bancorp did not recognize impairment losses resulting from the forfeiture or ineligibility of tax credits or other circumstances during the three months ended March 31, 2015 and 2014.