Fair Value (Schedule Of Assets And Liabilities Measured At Fair Value By Class On A Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading Securities	$ 56	$ 115
Other Assets, Fair Value Disclosure	97	91
Other Liabilities, Fair Value Disclosure	97	91
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	112	93
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	15,728	13,853
Financial and Nonfinancial Liabilities, Fair Value Disclosure	30	50
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure	214	304
Financial and Nonfinancial Liabilities, Fair Value Disclosure	150	125
Mutual Funds And Stock Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	87	185
Bank-owned life insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Noninterest Bearing Investments Fair Value Disclosure	504	497
Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Noninterest Bearing Investments Fair Value Disclosure	93	91
Interest-Only-Strip [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	19	20
Available-for-sale Securities [Member] | US Government Corporations and Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	13,839	12,009
Available-for-sale Securities [Member] | Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	1,291	1,154
Available-for-sale Securities [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	25
Asset-Backed Securities [Member] | Other Credit Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure		24
Derivative [Member] | Interest Rate Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	1	4
Other Liabilities, Fair Value Disclosure		1
Derivative [Member] | Interest Rate Swaps [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	36	49
Other Liabilities, Fair Value Disclosure	30	49
Derivative [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	6	11
Other Liabilities, Fair Value Disclosure	5	9
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	15,131	13,188
Trading Securities	56	115
Financial Instruments Sold, Not yet Purchased, at Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Mutual Funds And Stock Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	1	1
Fair Value, Inputs, Level 2 [Member] | Bank-owned life insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Noninterest Bearing Investments Fair Value Disclosure	504	497
Fair Value, Inputs, Level 2 [Member] | Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Noninterest Bearing Investments Fair Value Disclosure
Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | US Government Corporations and Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	13,814	12,009
Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	1,291	1,154
Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	25
Fair Value, Inputs, Level 2 [Member] | Asset-Backed Securities [Member] | Other (Including ABS CDOs) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure		24
Fair Value, Inputs, Level 2 [Member] | Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	37	53
Other Liabilities, Fair Value Disclosure	30	50
Fair Value, Inputs, Level 2 [Member] | Derivative [Member] | Interest Rate Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	1	4
Other Liabilities, Fair Value Disclosure		1
Fair Value, Inputs, Level 2 [Member] | Derivative [Member] | Interest Rate Swaps [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	36	49
Other Liabilities, Fair Value Disclosure	30	49
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	0	0
Financial Instruments Sold, Not yet Purchased, at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Noninterest Bearing Investments Fair Value Disclosure	93	73
Fair Value, Inputs, Level 3 [Member] | Interest-Only-Strip [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	19	20
Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | US Government Corporations and Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	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]
Investments, Fair Value Disclosure
Fair Value, Inputs, Level 3 [Member] | Asset-Backed Securities [Member] | Other (Including ABS CDOs) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure
Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	0	0
Other Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	111	184
Other Assets, Fair Value Disclosure	97	91
Financial Instruments Sold, Not yet Purchased, at Fair Value	48	25
Other Liabilities, Fair Value Disclosure	97	91
Fair Value, Inputs, Level 1 [Member] | Mutual Funds And Stock Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	86	184
Fair Value, Inputs, Level 1 [Member] | Private Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Noninterest Bearing Investments Fair Value Disclosure		18
Fair Value, Inputs, Level 1 [Member] | Available-for-sale Securities [Member] | US Government Corporations and Agencies Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	25	0
Fair Value, Inputs, Level 1 [Member] | Derivative [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	6	11
Other Liabilities, Fair Value Disclosure	5	9
Fair Value, Inputs, Level 1 [Member] | Derivative [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	6	11
Other Liabilities, Fair Value Disclosure	$ 5	$ 9