Fair Value (Fair Value Measurement - Reconciliation of Level 3 Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	$ 99	$ 1,151
Net realized/unrealized gains (losses) included in earnings, Assets	13	(119)
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0	0
Purchases, Assets	0	0
Sales, Assets	0	(911)
Issuances, Assets	0	60
Settlements, Assets	(68)	(71)
Transfers out of Level 3, Net Derivative Asset (Liability)		11
Fair Value, Assets, Ending balance	50	99
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1	11
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	3
Interest Rate Contract [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3	81
Loans Held-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	0
Net realized/unrealized gains (losses) included in earnings, Assets	0
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0
Purchases, Assets	0
Sales, Assets	0
Issuances, Assets	0
Settlements, Assets	0
Fair Value, Assets, Ending balance	3
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	3
Mortgage Servicing Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	0	952
Net realized/unrealized gains (losses) included in earnings, Assets	0	(101)	(560)
Net realized/unrealized gains (losses) included in other comprehensive income, Assets		0
Purchases, Assets		0
Sales, Assets		(911)
Issuances, Assets		60
Settlements, Assets		0
Transfers out of Level 3 Due to Deconsolidation or Discontinued Operations, Assets		0
Fair Value, Assets, Ending balance		0	952
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0
Retained Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	100	154
Net realized/unrealized gains (losses) included in earnings, Assets	13	23
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0	0
Purchases, Assets	0	0
Sales, Assets	0	0
Issuances, Assets	0	0
Settlements, Assets	(66)	(77)
Transfers out of Level 3 Due to Deconsolidation or Discontinued Operations, Assets		0
Fair Value, Assets, Ending balance	47	100
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0
Derivative Financial Instruments, Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability), Beginning balance		45
Gain (Loss) Included in Earnings, Net Derivative Asset (Liability)		(41)
Gain (Loss) Included in Other Comprehensive Income (Loss), Net Derivative Asset (Liability)		0
Purchases, Net Derivative Asset (Liability)		0
Sales, Net Derivative Asset (Liability)		0
Issuances, Net Derivative Asset (Liability)		0
Settlements, Net Derivative Asset (Liability)		(6)
Transfers out of Level 3, Net Derivative Asset (Liability)		11
Fair Value, Net Derivative Asset (Liability), Ending balance		(1)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		11
Interest Rate Contract [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability), Beginning balance	(1)	47
Gain (Loss) Included in Earnings, Net Derivative Asset (Liability)	0	(52)
Gain (Loss) Included in Other Comprehensive Income (Loss), Net Derivative Asset (Liability)	0	0
Purchases, Net Derivative Asset (Liability)	0	0
Sales, Net Derivative Asset (Liability)	0	0
Issuances, Net Derivative Asset (Liability)	0	0
Settlements, Net Derivative Asset (Liability)	2	4
Transfers out of Level 3, Net Derivative Asset (Liability)	(3)	0
Fair Value, Net Derivative Asset (Liability), Ending balance	0	(1)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(78)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0
Foreign Exchange Contract [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability), Beginning balance		(2)
Gain (Loss) Included in Earnings, Net Derivative Asset (Liability)		11
Gain (Loss) Included in Other Comprehensive Income (Loss), Net Derivative Asset (Liability)		0
Purchases, Net Derivative Asset (Liability)		0
Sales, Net Derivative Asset (Liability)		0
Issuances, Net Derivative Asset (Liability)		0
Settlements, Net Derivative Asset (Liability)		(2)
Transfers out of Level 3, Net Derivative Asset (Liability)		11
Fair Value, Net Derivative Asset (Liability), Ending balance		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		11
Fair Value, Inputs, Level 3 [Member] \| Mortgage Servicing Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net realized/unrealized gains (losses) included in earnings, Assets		$ (101)

Transfers out of Level 3 Due to Deconsolidation or Discontinued Operations, Assets

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Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy.

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in the income statement of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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