Summary of the Bancorp's Activities with its Principal Shareholders, Directors and Executives (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Outstanding balance on loans, net of participations and undrawn commitments	$ 63	$ 86
Commitments to Extend Credit
Related Party Transaction [Line Items]
Commitments to Extend Credit	63,827	62,050
Commitments to Extend Credit | Due to related party
Related Party Transaction [Line Items]
Commitments to Extend Credit	528	588
Commitments to Extend Credit | Director | Due to related party
Related Party Transaction [Line Items]
Commitments to Extend Credit	525	586
Commitments to Extend Credit | Executive Officer | Due to related party
Related Party Transaction [Line Items]
Commitments to Extend Credit	$ 3	$ 2