Derivatives (Derivative Financial Instruments - Additional Information) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2009
Derivative
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	$ 3	$ 6
Maximum Length Of Time Hedged In Interest Rate Cash Flow Hedge	2 years
Notional amount of the risk participations agreements	$ 2,838	2,467
Percentage of Vantiv Holding, LLC sold to Advent for cash and warrants			51.00%
Credit Risk
Derivative
Credit Risk Derivatives Average Life	2 years 10 months 24 days
Interest Rate Contract
Derivative
Fair value of risk participation agreements	$ 5	4
Interest Rate Contract | Cash Flow Hedging
Derivative
Deferred gains, net of tax, on cash flow hedges were recorded in accumulated other comprehensive income	9	10
Net deferred gains, net of tax, recorded in accumulated other comprehensive income are expected to be reclassified into earnings	3
Total collateral
Derivative
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	409	444
Derivative Liability, Fair Value, Amount Offset Against Collateral	365	$ 399
Amount of variation margin payment applied to derivative asset contracts	31
Amount of variation margin payment applied to derivative liability contracts	$ 74