Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Credit Losses On Lending-Related Commitments) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for credit losses	$ 44	$ (29)	$ 31	$ (17)
Lending-related commitments
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	30	40	30	42
Provision for credit losses	1	(6)	1	(8)
Balance at end of period	$ 31	$ 34	$ 31	$ 34