Income Taxes (Reconciliation of the Beginning and Ending Amounts of the Bancorp's Unrecognized Tax Benefits) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued
Unrecognized tax benefits at January 1		$ 24	[1]	$ 13	[1]	$ 11
Gross increases for tax positions taken during prior period		17		9		1
Gross decreases for tax positions taken during prior period		(1)		0		0
Gross increases for tax positions taken during current period		3		2		2
Settlements with taxing authorities		(7)		0		0
Lapse of applicable statute of limitations		(2)		0		(1)
Unrecognized tax benefits at December 31	[1]	$ 34		$ 24		$ 13

[1] (a ) Amounts represent unrecognized tax benefits that, if recognized, would affect the annual effective tax rate.