Derivatives (Net Gains (Losses) Relating to Derivative Instruments Designated as Cash Flow Hedges) (Detail) - Cash Flow Hedging - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	[1]	Jun. 30, 2018	Jun. 30, 2017	[1]
Derivative Instruments, Gain (Loss)
Amount of pretax net (losses) gains recognized in OCI	$ 4	$ 8		$ (5)	$ 3
Interest Income (Expense) Net
Derivative Instruments, Gain (Loss)
Amount of pretax net gains reclassified from OCI into net income	$ 0	$ 6		$ 1	$ 14

[1] For both the three and six months ended June 30, 2017, the amount of pretax net losses recognized in OCI represented the effective portion of the cumulative gains or losses on cash flow hedges and ineffectiveness was reported within noninterest income. Upon the adoption of ASU 2017-12, the Bancorp recorded a cumulative effect adjustment to retained earnings effective January 1, 2018 related to the elimination of the separate measurement of ineffect iveness. Refer to Note 3 for additional information.