Guarantees, Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Guarantor Obligations [Line Items]
Commitments to Extend Credit Expiring in One Year	$ 6,300
standby letters of credit expiring in one year	642
Standby Letters of Credit, Thereafter	181
Guarantor Obligations, Current Carrying Value	4
Reserve for Unfunded Lending Commitments	1
Letters of Credit, Deferred Commitment Fees	3
Risk-weighted values assigned to all off-balance sheet financial and derivative instruments	8,300	$ 7,600
Cash Reserve Deposit Required and Made	389
Minimum [Member]
Guarantor Obligations [Line Items]
Loss Contingency, Estimate of Possible Loss	0
Maximum [Member]
Guarantor Obligations [Line Items]
Loss Contingency, Estimate of Possible Loss	$ 35