Derivative And Credit-Related Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value of securities received as collateral for derivative assets	$ 1
Cash received as collateral for derivative assets	180
Cash posted as collateral for derivative liabilities	2
Aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	0
Gain (loss) on foreign currency derivatives used as economic hedges	0	$ 0
Net gain on open foreign currency positions	0
Allowance for credit losses on lending-related commitments	30	42
Allowance for credit losses on lending-related commitments, unused commitments to extend credit	$ 24	27
Final year of expiration for outstanding letters of credit	2028
Risk participation agreements covering standby and commercial letters of credit	$ 136	127
Standby and commercial letters of credit outstanding	3,300	3,300
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities	34	40
Deferred fees on standby and commercial letters of credit included in accrued expenses and other liabilities	28	25
Allowance for credit losses on lending-related commitments, amount related to standby and commercial letters of credit	6	15
Notional Amount of Derivative Credit Risk Participation Agreements	703	$ 549
Maximum estimated exposure to credit risk participation agreements assuming 100% default	$ 7
Weighted average remaining maturity of credit risk participation agreements, in years	3 years 5 months 13 days