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Fair Value Of Financial Instruments (Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	$ 3,937	$ 4,439	$ 4,188	$ 4,467
Fair value, liabilities	7,622	11,821	7,938	9,916
(Decrease) increase in accrued interest payable	(25)	(22)
Loans Receivable [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	2,025	2,327	2,046	2,183
Valuation Technique	Quoted market prices adjusted for financial guarantees provided to VIE obligations
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	1,076	867	1,077	835
Valuation Technique	Discounted cash flow
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, liabilities	2,864
Valuation Technique	Quoted market prices of VIE assets adjusted for financial guarantees provided
Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	25	51	24	41
Commercial Mortgage-Backed [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	15	29	22	23
Commercial Mortgage-Backed [Member] | Credit Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	2,183
Valuation Technique	BET Model
Multi-Sector CDO [Member] | Credit Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	928
Valuation Technique	Direct Price Model
Other Assets [Member] | Credit Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	$ 1,376
Valuation Technique	BET Model
Impact Of Financial Guarantee [Member] | Loans Receivable [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	0.00%
Range, maximum	114.00%
Weighted Average	7.00%
Impact Of Financial Guarantee [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	0.00%
Range, maximum	26.00%
Weighted Average	3.00%
Recovery Rates [Member] | Loan Repurchase Commitments [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	25.00%
Range, maximum	75.00%
Weighted Average	71.00%
Recovery Rates [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	22.00%
Range, maximum	90.00%
Weighted Average	50.00%
Recovery Rates [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	42.00%
Range, maximum	75.00%
Weighted Average	47.00%
Breach Rate [Member] | Loan Repurchase Commitments [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	65.00%
Range, maximum	94.00%
Weighted Average	76.00%
Nonperformance Risk [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	4.00%
Range, maximum	57.00%
Weighted Average	49.00%
Nonperformance Risk [Member] | Multi-Sector CDO [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	57.00%
Range, maximum	57.00%
Weighted Average	57.00%
Nonperformance Risk [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	10.00%
Range, maximum	57.00%
Weighted Average	44.00%
Weighted Average Life [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum (in years)	0.2
Range, maximum (in years)	6.4
Weighted average (in years)	4.7
Weighted Average Life [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum (in years)	0.2
Range, maximum (in years)	13.4
Weighted average (in years)	3.1
CMBS Spreads [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum (in percentage)	1.00%
Range, maximum (in percentage)	23.00%
Weighted average (in percentage)	12.00%

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- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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This element represents a liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

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The increase (decrease) during the reporting period in interest payable, which represents the amount owed to note holders, bond holders, and other parties for interest earned on loans or credit extended to the reporting entity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

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