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		Dec. 31, 2019	Dec. 31, 2018
Cash and due from banks		$ 973	$ 1,390
Interest-bearing deposits with banks		4,845	3,171
Total loans, net of allowance for loan losses		49,732	49,492
Demand deposits (noninterest-bearing)		27,382	28,690
Customer certificates of deposit		2,978	2,131
Other time deposits		133	0
Total deposits		57,295	55,561
Short-term borrowings		71	44
Medium- and long-term debt		7,269	6,463
Carrying Amount
Cash and due from banks		973	1,390
Interest-bearing deposits with banks		4,845	3,171
Loans held-for-sale		6	3
Total loans, net of allowance for loan losses	[1]	49,732	49,492
Customers' liability on acceptances outstanding		2	4
Restricted equity investments		248	248
Nonmarketable equity securities	[2]	5	6
Demand deposits (noninterest-bearing)		27,382	28,690
Interest-bearing deposits		26,802	24,740
Customer certificates of deposit		2,978	2,131
Other time deposits		133
Total deposits		57,295	55,561
Short-term borrowings		71	44
Acceptances outstanding		2	4
Medium- and long-term debt		7,269	6,463
Credit-related financial instruments		(57)	(57)
Estimated Fair Value
Cash and due from banks		973	1,390
Interest-bearing deposits with banks		4,845	3,171
Loans held-for-sale		6	3
Total loans, net of allowance for loan losses	[1]	49,975	48,889
Customers' liability on acceptances outstanding		2	4
Restricted equity investments		248	248
Nonmarketable equity securities	[2]	10	11
Demand deposits (noninterest-bearing)		27,382	28,690
Interest-bearing deposits		26,802	24,740
Customer certificates of deposit		2,968	2,100
Other time deposits		133
Total deposits		57,285	55,530
Short-term borrowings		71	44
Acceptances outstanding		2	4
Medium- and long-term debt		7,316	6,436
Credit-related financial instruments		(57)	(57)
Level 1 | Estimated Fair Value
Cash and due from banks		973	1,390
Interest-bearing deposits with banks		4,845	3,171
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		2	4
Restricted equity investments		248	248
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Other time deposits		0
Total deposits		0	0
Short-term borrowings		71	44
Acceptances outstanding		2	4
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		6	3
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)		27,382	28,690
Interest-bearing deposits		26,802	24,740
Customer certificates of deposit		2,968	2,100
Other time deposits		133
Total deposits		57,285	55,530
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		7,316	6,436
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]	49,975	48,889
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
Total deposits		0	0
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		0	0
Credit-related financial instruments		(57)	(57)
Nonrecurring
Total loans, net of allowance for loan losses		$ 70	$ 108

[1] Included $70 million and $108 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2019 and 2018, 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.