Summary of the Bancorp's Activities with its Principal Shareholders, Directors and Executives (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Outstanding balance on loans, net of participations and undrawn commitments	$ 97	$ 63
Commitments to Extend Credit
Related Party Transaction [Line Items]
Commitments to Extend Credit	66,884	63,827
Commitments to Extend Credit | Due to related party
Related Party Transaction [Line Items]
Commitments to Extend Credit	836	528
Commitments to Extend Credit | Director | Due to related party
Related Party Transaction [Line Items]
Commitments to Extend Credit	831	525
Commitments to Extend Credit | Executive Officer | Due to related party
Related Party Transaction [Line Items]
Commitments to Extend Credit	$ 5	$ 3