Guarantees, Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Guarantor Obligations [Line Items]
Current Fiscal Year End Date	--12-31
Operating Leases, Future Minimum Payments, Due in Three Years	$ 36
Operating Leases, Future Minimum Payments, Due in Four Years	29
Operating Leases, Future Minimum Payments, Due in Five Years	25
Operating Leases, Future Minimum Payments Due, Next Twelve Months	40
Operating Leases, Future Minimum Payments, Due Thereafter	76
Commitments to Extend Credit Expiring in One Year	6,200
standby letters of credit expiring in one year	610
Standby Letters of Credit, Thereafter	307
Guarantor Obligations, Current Carrying Value	5
Reserve for Unfunded Lending Commitments	1
Letters of Credit, Deferred Commitment Fees	4
Commitments for Private Equity and Other Noninterest-bearing Investments	31
Commitments for Private Equity or Other Non-Interest Bearing Investments Prohibited by the Volcker Rule	4
Risk-weighted values assigned to all off-balance sheet financial and derivative instruments	6,800	$ 6,500
Cash Reserve Deposit Required and Made	366
Capital Lease Obligations, Current	1
Accumulated Amortization, Deferred Finance Costs	1
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	2
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years	2
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years	1
Operating Leases, Rent Expense, Net	$ 61	$ 65	$ 63