Fair Value (Schedule Of Assets And Liabilities Measured At Fair Value By Class On A Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	$ 15,161	$ 13,372
Trading account, at fair value	148	115
Total assets	16,069	14,250
Securities sold, not yet purchased	95	25
Financial and Nonfinancial Liabilities, Fair Value Disclosure	237	175
Mutual Funds And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	72	185
Bank-owned life insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	507	497
Private Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	95	91
Interest-Only-Strip [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	18	20
Warranty, Rights and Obligations, Fair Value Option [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	102	91
Other liabilities	102	91
Available-for-sale Securities [Member] | U.S. Treasury, Agencies And Corporations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	13,731	12,009
Available-for-sale Securities [Member] | Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	1,334	1,154
Asset-Backed Securities [Member] | Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	24	24
Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	38	64
Other liabilities	40
Derivatives [Member] | Interest Rate Related And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	1	4
Other liabilities		1
Derivatives [Member] | Interest Rate Swaps For Customers [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	28	49
Other liabilities	33	49
Derivatives [Member] | Foreign Currency Exchange Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	9	11
Other liabilities	7	9
Derivatives [Member] | Total Return Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities		59
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	96	184
Other assets		91
Total assets	207	304
Securities sold, not yet purchased	95	25
Financial and Nonfinancial Liabilities, Fair Value Disclosure	204	125
Level 1 [Member] | Mutual Funds And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	71	184
Level 1 [Member] | Private Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments		18
Level 1 [Member] | Warranty, Rights and Obligations, Fair Value Option [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	102
Other liabilities	102	91
Level 1 [Member] | Available-for-sale Securities [Member] | U.S. Treasury, Agencies And Corporations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	25	0
Level 1 [Member] | Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	9	11
Other liabilities	7
Level 1 [Member] | Derivatives [Member] | Foreign Currency Exchange Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	9	11
Other liabilities	7	9
Level 1 [Member] | Derivatives [Member] | Total Return Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities		9
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	15,065	13,188
Trading account, at fair value	148	115
Total assets	15,749	13,853
Securities sold, not yet purchased	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	33	50
Level 2 [Member] | Mutual Funds And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	1	1
Level 2 [Member] | Bank-owned life insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	507	497
Level 2 [Member] | Private Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments
Level 2 [Member] | Available-for-sale Securities [Member] | U.S. Treasury, Agencies And Corporations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	13,706	12,009
Level 2 [Member] | Available-for-sale Securities [Member] | Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	1,334	1,154
Level 2 [Member] | Asset-Backed Securities [Member] | Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	24	24
Level 2 [Member] | Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	29	53
Other liabilities	33
Level 2 [Member] | Derivatives [Member] | Interest Rate Related And Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	1
Other liabilities		1
Level 2 [Member] | Derivatives [Member] | Interest Rate Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets		4
Level 2 [Member] | Derivatives [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets		49
Other liabilities		49
Level 2 [Member] | Derivatives [Member] | Interest Rate Swaps For Customers [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	28
Other liabilities	33
Level 2 [Member] | Derivatives [Member] | Total Return Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities		50
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0	0
Total assets	113	93
Securities sold, not yet purchased	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Private Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other noninterest-bearing investments	95	73
Fair Value, Inputs, Level 3 [Member] | Interest-Only-Strip [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	18	20
Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | U.S. Treasury, Agencies And Corporations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0	0
Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities
Fair Value, Inputs, Level 3 [Member] | Asset-Backed Securities [Member] | Other [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities
Fair Value, Inputs, Level 3 [Member] | Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	0	0
Other liabilities	$ 0
Fair Value, Inputs, Level 3 [Member] | Derivatives [Member] | Total Return Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other liabilities		$ 0