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		Sep. 30, 2021	Dec. 31, 2020
Cash and due from banks		$ 1,050	$ 1,031
Interest-bearing deposits with banks		22,539	14,736
Total loans, net of allowance for loan losses		47,586	51,343
Demand deposits (noninterest-bearing)		44,093	39,420
Customer certificates of deposit		2,091	2,133
Total deposits		82,284	72,869
Total Medium- and long-term debt		2,837	5,728
Carrying Amount
Cash and due from banks		1,050	1,031
Interest-bearing deposits with banks		22,539	14,736
Loans held-for-sale		7	5
Total loans, net of allowance for loan losses	[1]	47,586	51,343
Customers' liability on acceptances outstanding		3	1
Restricted equity investments		92	207
Nonmarketable equity securities	[2]	6	5
Demand deposits (noninterest-bearing)		44,093	39,420
Interest-bearing deposits		36,100	31,316
Customer certificates of deposit		2,091	2,133
Total deposits		82,284	72,869
Acceptances outstanding		3	1
Total Medium- and long-term debt		2,837	5,728
Credit-related financial instruments		(51)	(68)
Estimated Fair Value
Cash and due from banks		1,050	1,031
Interest-bearing deposits with banks		22,539	14,736
Loans held-for-sale		7	5
Total loans, net of allowance for loan losses	[1]	48,146	50,601
Customers' liability on acceptances outstanding		3	1
Restricted equity investments		92	207
Nonmarketable equity securities	[2]	10	9
Demand deposits (noninterest-bearing)		44,093	39,420
Interest-bearing deposits		36,100	31,316
Customer certificates of deposit		2,090	2,133
Total deposits		82,283	72,869
Acceptances outstanding		3	1
Total Medium- and long-term debt		2,904	5,790
Credit-related financial instruments		(51)	(68)
Level 1 | Estimated Fair Value
Cash and due from banks		1,050	1,031
Interest-bearing deposits with banks		22,539	14,736
Loans held-for-sale		0	0
Total loans, net of allowance for loan losses	[1]	0	0
Customers' liability on acceptances outstanding		3	1
Restricted equity investments		92	207
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Total deposits		0	0
Acceptances outstanding		3	1
Total 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		7	5
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)		44,093	39,420
Interest-bearing deposits		36,100	31,316
Customer certificates of deposit		2,090	2,133
Total deposits		82,283	72,869
Acceptances outstanding		0	0
Total Medium- and long-term debt		2,904	5,790
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]	48,146	50,601
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
Total deposits		0	0
Acceptances outstanding		0	0
Total Medium- and long-term debt		0	0
Credit-related financial instruments		(51)	(68)
Nonrecurring
Total loans, net of allowance for loan losses		$ 148	$ 150

[1] Included $148 million and $150 million of loans recorded at fair value on a nonrecurring basis at September 30, 2021 and December 31, 2020, 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.