Fair Value Measurements (Estimated Fair Values Of Financial Instruments Not Recorded At Fair Value In Their Entirety On A Recurring Basis) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Cash and due from banks		$ 848	$ 973
Interest-bearing deposits with banks		4,007	4,845
Total loans, net of allowance for loan losses		52,542	49,732
Demand deposits (noninterest-bearing)		27,646	27,382
Customer certificates of deposit		2,958	2,978
Other time deposits		0	133
Total deposits		57,366	57,295
Short-term borrowings		2,263	71
Medium- and long-term debt		7,434	7,269
Carrying Amount
Cash and due from banks		848	973
Interest-bearing deposits with banks		4,007	4,845
Loans held-for-sale		5	6
Total loans, net of allowance for loan losses	[1]	52,542	49,732
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		279	248
Nonmarketable equity securities	[2]	5	5
Demand deposits (noninterest-bearing)		27,646	27,382
Interest-bearing deposits		26,762	26,802
Customer certificates of deposit		2,958	2,978
Other time deposits		0	133
Total deposits		57,366	57,295
Short-term borrowings		2,263	71
Acceptances outstanding		2	2
Medium- and long-term debt		7,434	7,269
Credit-related financial instruments		(84)	(57)
Estimated Fair Value
Cash and due from banks		848	973
Interest-bearing deposits with banks		4,007	4,845
Loans held-for-sale		5	6
Total loans, net of allowance for loan losses	[1]	52,108	49,975
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		279	248
Nonmarketable equity securities	[2]	10	10
Demand deposits (noninterest-bearing)		27,646	27,382
Interest-bearing deposits		26,762	26,802
Customer certificates of deposit		2,959	2,968
Other time deposits		0	133
Total deposits		57,367	57,285
Short-term borrowings		2,263	71
Acceptances outstanding		2	2
Medium- and long-term debt		7,224	7,316
Credit-related financial instruments		(84)	(57)
Level 1 | Estimated Fair Value
Cash and due from banks		848	973
Interest-bearing deposits with banks		4,007	4,845
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		2	2
Restricted equity investments		279	248
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits		0	0
Total deposits		0	0
Short-term borrowings		2,263	71
Acceptances outstanding		2	2
Medium- and long-term debt		0	0
Credit-related financial instruments		0	0
Level 2 | Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Loans held-for-sale		5	6
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		27,646	27,382
Interest-bearing deposits		26,762	26,802
Customer certificates of deposit		2,959	2,968
Other time deposits		0	133
Total deposits		57,367	57,285
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		7,224	7,316
Credit-related financial instruments		0	0
Level 3 | Estimated Fair Value
Cash and due from banks		0	0
Interest-bearing deposits with banks		0	0
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	52,108	49,975
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits		0	0
Total deposits		0	0
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		0	0
Credit-related financial instruments		(84)	(57)
Nonrecurring
Total loans, net of allowance for loan losses		$ 90	$ 70

[1] Included $90 million and $70 million of loans recorded at fair value on a nonrecurring basis at March 31, 2020 and December 31, 2019, respectively.

[2] Certain investments that are measured at fair value using the net asset value have not been classified in the fair value hierarchy. The fair value amounts presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.