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, 2015	Dec. 31, 2014
Cash and due from banks		$ 1,157	$ 1,026
Interest-bearing deposits with banks		4,990	5,045
Investment securities held-to-maturity		1,981	1,935
Total loans, net of allowance for loan losses		48,450	47,999
Demand deposits (noninterest-bearing)		30,839	27,224
Customer certificates of deposit		3,552	4,421
Total deposits		59,853	57,486
Short-term borrowings		23	116
Medium- and long-term debt		3,058	2,675
Carrying Amount
Cash and due from banks		1,157	1,026
Interest-bearing deposits with banks		4,990	5,045
Investment securities held-to-maturity		1,981	1,935
Loans held-for-sale	[1]	21	5
Total loans, net of allowance for loan losses	[2]	48,450	47,999
Customers' liability on acceptances outstanding		5	10
Nonmarketable equity securities		10	11	[3]
Restricted equity investments		92	92
Demand deposits (noninterest-bearing)		30,839	27,224
Interest-bearing deposits		25,462	25,841
Customer certificates of deposit		3,552	4,421
Total deposits		59,853	57,486
Short-term borrowings		23	116
Acceptances outstanding		5	10
Medium- and long-term debt		3,058	2,675
Credit-related financial instruments		(83)	(85)
Estimated Fair Value
Cash and due from banks		1,157	1,026
Interest-bearing deposits with banks		4,990	5,045
Investment securities held-to-maturity		1,973	1,933
Loans held-for-sale	[1]	21	5
Total loans, net of allowance for loan losses	[2]	48,269	47,932
Customers' liability on acceptances outstanding		5	10
Nonmarketable equity securities	[3]	18	18
Restricted equity investments		92	92
Demand deposits (noninterest-bearing)		30,839	27,224
Interest-bearing deposits		25,462	25,841
Customer certificates of deposit		3,536	4,411
Total deposits		59,837	57,476
Short-term borrowings		23	116
Acceptances outstanding		5	10
Medium- and long-term debt		3,032	2,681
Credit-related financial instruments		(83)	(85)
Level 1 | Estimated Fair Value
Cash and due from banks		1,157	1,026
Interest-bearing deposits with banks		4,990	5,045
Investment securities held-to-maturity		0	0
Loans held-for-sale	[1]	0	0
Total loans, net of allowance for loan losses	[2]	0	0
Customers' liability on acceptances outstanding		5	10
Nonmarketable equity securities	[3]	0	0
Restricted equity investments		92	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		23	116
Acceptances outstanding		5	10
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		1,973	1,933
Loans held-for-sale	[1]	21	5
Total loans, net of allowance for loan losses	[2]	0	0
Customers' liability on acceptances outstanding		0	0
Nonmarketable equity securities	[3]	0	0
Restricted equity investments		0	0
Demand deposits (noninterest-bearing)		30,839	27,224
Interest-bearing deposits		25,462	25,841
Customer certificates of deposit		3,536	4,411
Total deposits		59,837	57,476
Short-term borrowings		0	0
Acceptances outstanding		0	0
Medium- and long-term debt		3,032	2,681
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	[1]	0	0
Total loans, net of allowance for loan losses	[2]	48,269	47,932
Customers' liability on acceptances outstanding		0	0
Nonmarketable equity securities	[3]	18	18
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		(83)	(85)
Nonrecurring
Loans held-for-sale		8	0
Nonmarketable equity securities		1	2
Loans		153	64
Nonrecurring | Level 2
Nonmarketable equity securities		0	0
Loans		0	0
Nonrecurring | Level 3
Nonmarketable equity securities		1	2
Loans		$ 153	$ 64

[1] Included $8 million and no impaired loans held-for-sale recorded at fair value on a nonrecurring basis at December 31, 2015 and 2014, respectively.

[2] Included $153 million and $64 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2015 and 2014, respectively.

[3] Included $1 million and $2 million of nonmarketable equity securities recorded at fair value on a nonrecurring basis at December 31, 2015 and 2014, respectively.