Fair Value (Schedule Of Assets With Fair Value Changes On Nonrecurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Principal amount of other real estate owned property sold	$ 2
Fair value of assets measured on nonrecurring basis	2		$ 54
Gains (losses) from fair value changes	(2)	$ (15)
Impaired Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	1		52
Gains (losses) from fair value changes	(1)	(15)
Private Equity Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	1		1
Gains (losses) from fair value changes	(1)	$ 0
Other Real Estate Owned [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		1
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		0
Fair Value, Inputs, Level 1 [Member] | Impaired Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		0
Fair Value, Inputs, Level 1 [Member] | Private Equity Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		0
Fair Value, Inputs, Level 1 [Member] | Other Real Estate Owned [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	1		53
Fair Value, Inputs, Level 2 [Member] | Impaired Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	1		52
Fair Value, Inputs, Level 2 [Member] | Private Equity Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		0
Fair Value, Inputs, Level 2 [Member] | Other Real Estate Owned [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		1
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	1		1
Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	0		0
Fair Value, Inputs, Level 3 [Member] | Private Equity Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	1		1
Fair Value, Inputs, Level 3 [Member] | Other Real Estate Owned [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets measured on nonrecurring basis	$ 0		$ 0