Derivative Instruments And Hedging Activities (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative [Line Items]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion		$ (7)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		11	$ (5)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		2	0
Fair values of derivative assets reduced (increased) by net credit valuation adjustments		6	1
Total derivatives, Notional amount		$ 12,224		$ 7,481
Derivative, Floor Interest Rate		1.50%
Derivative, Average Remaining Maturity		2 years 8 months 4 days
Derivative, Average Fixed Interest Rate 2.08%		2.08%
Senior Notes		$ 1,141		637
Derivative, Cost of Hedge		7
Floors Purchased as Hedging Instruments		$ 9
Derivative, Fixed Interest Rate		3.35%
Derivative, Fixed Interest Rate 3.5%		3.50%
Derivative, Average Fixed Interest Rate		3.43%
Derivative, Notional Amount Commercial Loans		$ 1,300		700
Derivative Asset, Notional Amount		150
Cash collateral pledged for derivative liabilities		50
Additional collateral that would be required to be pledge if credit rating was downgraded by one notch		1
Derivative Instrument, Noninterest Income (Expense)		8	10
Derivatives Designated As Hedging Instrument Offset To Interest Expense		0	0
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities		1	1
Derivatives Designated As Hedging Instruments [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		11	(5)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		2	0
Total derivatives, Notional amount		5,338		1,187
Derivatives Designated As Hedging Instrument Offset To Interest Expense		0	0
Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Total derivatives, Notional amount		6,886		6,294
Derivative Instrument, Noninterest Income (Expense)		8	10
Interest Rate Swap [Member] | Derivatives Designated As Hedging Instruments [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Total derivatives, Notional amount		1,000		500
Interest Rate Swap [Member] | Derivatives Designated As Hedging Instruments [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		8
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	2
Total derivatives, Notional amount		1,338		687
Interest Rate Swap [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Total derivatives, Notional amount		449		253
Derivative Instrument, Noninterest Income (Expense)		0	(2)
Interest Rate Swaps For Customers [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Total derivatives, Notional amount		3,035		2,826
Derivative Instrument, Noninterest Income (Expense)		(41)	45
Foreign Exchange [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Total derivatives, Notional amount		367		389
Derivative Instrument, Noninterest Income (Expense)		5	$ 5
Other Liabilities [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		25		39
Other Liabilities [Member] | Derivatives Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0
Other Liabilities [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		25		39
Other Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Gross amounts recognized		25		39
Other Liabilities [Member] | Interest Rate Swap [Member] | Derivatives Designated As Hedging Instruments [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0
Other Liabilities [Member] | Interest Rate Swap [Member] | Derivatives Designated As Hedging Instruments [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		0		0
Other Liabilities [Member] | Interest Rate Swap [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		1		1
Other Liabilities [Member] | Interest Rate Swaps For Customers [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		22		36
Other Liabilities [Member] | Foreign Exchange [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		2		$ 2
Senior Notes [Member]
Derivative [Line Items]
Senior Notes		$ 500

[1] Amounts recognized in OCI and reclassified from AOCI represent the effective portion of the derivative gain (loss). For the 12 months following March 31, 2019, we estimate that $(7) million will be reclassified from AOCI into interest income