Investments in Securities Trading 1 (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 42,522	$ 74,198
Mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	22,625	24,350
Fannie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	6,245	7,424
Freddie Mac [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	2,840	2,732
Ginnie Mae [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	280	287
Alt-A private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,276	1,349
Subprime private-label securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	1,265	1,280
CMBS [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	9,920	10,411
Mortgage revenue bonds [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	681	724
Other mortgage-related securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	118	143
Non-mortgage-related Securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	19,897	49,848
U.S. Treasury Securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	19,897	47,737
Asset-backed securities [Member]
Schedule of Investments in Trading Securities [Line Items]
Trading, at fair value	$ 0	$ 2,111

Debt securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for debt securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition.

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.4)

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 45

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-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562

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

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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-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 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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-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 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

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-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 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Implementation Guide (Q and A)

-Number FAS115

-Paragraph 35

-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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