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Fair Value Of Financial Instruments (Difference Between Aggregate Fair Value And Aggregate Remaining Contractual Principal Balance Outstanding) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans receivable, Contractual Outstanding Principal	$ 2,916	$ 3,481
Variable interest entity notes, Contractual Outstanding Principal	9,015	13,583
Loans receivable, Fair Value	1,892	2,046
Variable interest entity notes, Fair Value	3,626	4,754
Loans receivable, Difference	1,024	1,435
Variable interest entity notes, Difference	5,389	8,829
Residential Mortgage Loans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans receivable, Contractual Outstanding Principal	2,430	2,769
Loans receivable, 90 days or more past due, Contractual Outstanding Principal	241	259
Loans receivable, Fair Value	1,746	1,895
Loans receivable, 90 days or more past due, Fair Value	46
Loans receivable, Difference	684	874
Loans receivable, 90 days or more past due, Difference	195	259
Other Loans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans receivable, Contractual Outstanding Principal	39	129
Loans receivable, 90 days or more past due, Contractual Outstanding Principal	206	324
Loans receivable, Fair Value	16	43
Loans receivable, 90 days or more past due, Fair Value	84	108
Loans receivable, Difference	23	86
Loans receivable, 90 days or more past due, Difference	$ 122	$ 216

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- Definition

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- Definition

Fair Value Option Aggregate Fair Value Long Term Debt Instruments

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- Definition

Fair Value Option Contractual Outstanding Principal Loans Receivable

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- Definition

Fair Value Option Contractual Outstanding Principal Long Term Debt Instruments

+ References

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- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph d(1)

-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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- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of long-term debt instruments that have contractual principal amounts and for which the fair value option has been elected.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph d(2)

-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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- Definition

This item represents the aggregate fair value of loans held as assets that are 90 days or more past due for which the fair value option has been elected.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph e(1)

-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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- Definition

For loans held as assets for which the fair value option has been elected, this item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of those loans that are 90 days or more past due.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (e)(3)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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- Definition

This item represents the aggregate fair value of loans held as assets that are in nonaccrual status for which the fair value option has been elected, if the entity's policy is to recognize interest income separately from other changes in fair value.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (e)(2)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph e(2)

-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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