Investment Securities (Rollforward of Cumulative OTTI Credit Losses Recognized in Earnings) (Details) (USD $) In Millions	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Residential Mortgage-backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Sep. 30, 2010 Residential Mortgage-backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Sep. 30, 2011 Residential Mortgage-backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Sep. 30, 2010 Residential Mortgage-backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Sep. 30, 2011 Commercial Mortgage Backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Sep. 30, 2010 Commercial Mortgage Backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Jun. 30, 2011 Commercial Mortgage Backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Jun. 30, 2010 Commercial Mortgage Backed Securities [Member] Mortgage-backed Securities Non-agency [Member]	Sep. 30, 2011 Asset backed [Member]	Sep. 30, 2010 Asset backed [Member]	Sep. 30, 2011 Asset backed [Member]	Sep. 30, 2010 Asset backed [Member]	Sep. 30, 2011 Other Debt Securities [Member]	Jun. 30, 2011 Other Debt Securities [Member]	Sep. 30, 2010 Other Debt Securities [Member]	Jun. 30, 2010 Other Debt Securities [Member]	Dec. 31, 2009 Other Debt Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Beginning balance	$ (1,012)	$ (840)	$ (955)	$ (642)	$ (761)	$ (621)	$ (709)	$ (479)	$ (11)	$ (6)	$ (6)	$ (9)	$ (232)	$ (198)	$ (223)	$ (145)	$ (12)	$ (13)	$ (12)	$ (12)	$ (12)
Loss where impairment was not previously recognized	(2)	(15)	(9)	(55)	(2)	(15)	(5)	(41)		(3)					(3)	(11)	(1)
Additional loss where credit impairment was previously recognized	(33)	(56)	(99)	(226)	(28)	(42)	(88)	(170)					(5)	(14)	(11)	(56)
Reduction due to credit impaired securities sold			16	12			11	12	5
Ending balance	$ (1,047)	$ (911)	$ (1,047)	$ (911)	$ (791)	$ (678)	$ (791)	$ (678)	$ (6)	$ (9)	$ (6)	$ (9)	$ (237)	$ (212)	$ (237)	$ (212)	$ (13)	$ (13)	$ (12)	$ (12)	$ (12)

This item represents an increase to the cumulative amount of credit losses recognized in earnings for an other than temporary impairment (OTTI) of a debt security held for which a previous OTTI was recognized and the investor does not intend to sell the debt security and it is not more likely than not that the investor will be required to sell the debt security before recovery of its amortized cost basis.

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 18B

-Subparagraph e

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 50

-Paragraph 8

-Subparagraph (e)

-SubTopic 10

-Topic 320

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27340-111563

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents an increase to the cumulative amount of credit losses recognized in earnings for an other than temporary impairment (OTTI) of a debt security held for which no such other than temporary impairment (OTTI) was previously recognized.

+ References

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 18B

-Subparagraph b

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 50

-Paragraph 8

-Subparagraph (b)

-SubTopic 10

-Topic 320

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27340-111563

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsNoPreviousImpairment
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 50

-Paragraph 8

-SubTopic 10

-Topic 320

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27340-111563

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 18B

-Subparagraph a

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 18B

-Subparagraph g

-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.

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents reductions in the cumulative amount of credit losses recognized in earnings for an other than temporary impairment (OTTI) of a debt security because of the sale of impaired securities during the period.

+ References

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 18B

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 50

-Paragraph 8

-Subparagraph (c)

-SubTopic 10

-Topic 320

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27340-111563

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration