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, 2016	Dec. 31, 2015
Cash and due from banks		$ 1,249	$ 1,157
Interest-bearing deposits with banks		5,969	4,990
Investment securities held-to-maturity		1,582	1,981
Total loans, net of allowance for loan losses		48,358	48,450
Demand deposits (noninterest-bearing)		31,540	30,839
Customer certificates of deposit		2,806	3,552
Total deposits		58,985	59,853
Short-term borrowings		25	23
Medium- and long-term debt		5,160	3,058
Carrying Amount
Cash and due from banks		1,249	1,157
Interest-bearing deposits with banks		5,969	4,990
Investment securities held-to-maturity		1,582	1,981
Loans held-for-sale		4	21	[1]
Total loans, net of allowance for loan losses	[2]	48,358	48,450
Customers' liability on acceptances outstanding		5	5
Restricted equity investments		207	92
Nonmarketable equity securities	[3]	11	10	[4]
Demand deposits (noninterest-bearing)		31,540	30,839
Interest-bearing deposits		24,639	25,462
Customer certificates of deposit		2,806	3,552
Total deposits		58,985	59,853
Short-term borrowings		25	23
Acceptances outstanding		5	5
Medium- and long-term debt		5,160	3,058
Credit-related financial instruments		(73)	(83)
Estimated Fair Value
Cash and due from banks		1,249	1,157
Interest-bearing deposits with banks		5,969	4,990
Investment securities held-to-maturity		1,576	1,973
Loans held-for-sale		4	21	[1]
Total loans, net of allowance for loan losses	[2]	48,250	48,269
Customers' liability on acceptances outstanding		5	5
Restricted equity investments		207	92
Nonmarketable equity securities	[3]	16	18	[4]
Demand deposits (noninterest-bearing)		31,540	30,839
Interest-bearing deposits		24,639	25,462
Customer certificates of deposit		2,731	3,536
Total deposits		58,910	59,837
Short-term borrowings		25	23
Acceptances outstanding		5	5
Medium- and long-term debt		5,132	3,032
Credit-related financial instruments		(73)	(83)
Level 1 | Estimated Fair Value
Cash and due from banks		1,249	1,157
Interest-bearing deposits with banks		5,969	4,990
Investment securities held-to-maturity		0	0
Loans held-for-sale		0	0	[1]
Total loans, net of allowance for loan losses	[2]	0	0
Customers' liability on acceptances outstanding		5	5
Restricted equity investments		207	92
Demand deposits (noninterest-bearing)		0	0
Interest-bearing deposits		0	0
Customer certificates of deposit		0	0
Total deposits		0	0
Short-term borrowings		25	23
Acceptances outstanding		5	5
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
Investment securities held-to-maturity		1,576	1,973
Loans held-for-sale		4	21	[1]
Total loans, net of allowance for loan losses	[2]	0	0
Customers' liability on acceptances outstanding		0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		31,540	30,839
Interest-bearing deposits		24,639	25,462
Customer certificates of deposit		2,731	3,536
Total deposits		58,910	59,837
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		5,132	3,032
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
Investment securities held-to-maturity		0	0
Loans held-for-sale		0	0	[1]
Total loans, net of allowance for loan losses	[2]	48,250	48,269
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
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		0	0
Credit-related financial instruments		(73)	(83)
Nonrecurring
Loans held-for-sale			8
Total loans, net of allowance for loan losses		$ 282	153
Nonmarketable equity securities	[5]		$ 1

[1] Included $8 million impaired loans held-for-sale recorded at fair value on a nonrecurring basis at December 31, 2015.

[2] Included $282 million and $153 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2016 and 2015, respectively.

[3] 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.

[4] Included $1 million of nonmarketable equity securities recorded at fair value on a nonrecurring basis at December 31, 2015.

[5] 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.