Commitments, Guarantees, And Contingent Liabilities (Narrative) (Details) $ in Millions	Jun. 30, 2017 USD ($)
Guarantor Obligations [Line Items]
Letters of credit, accrued liability	$ 5
Reserve for unfunded lending commitments	1
Deferred commitment fees	4
Commitments for Private Equity and Other Noninterest-bearing Investments	27
Commitments for Private Equity or Other Non-Interest Bearing Investments Prohibited by the Volcker Rule	4
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	$ 20