Financial Guarantees Financial Guarantees and Maximum Recovery (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Financial Guarantees and Maximum Recovery [Line Items]
Maximum Exposure	$ 28,802	$ 31,573
Guaranty Obligation	282	329
Maximum Recovery	10,976	11,726
Fair Value of guaranty obligations in Investments in securities	433	488
Unconsolidated VIEs [Member] \| Unconsolidated Fannie Mae MBS [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Maximum Exposure	13,333	15,069
Guaranty Obligation	147	194
Maximum Recovery	8,269	8,857
Unconsolidated VIEs [Member] \| Other guaranty arrangements [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Maximum Exposure	15,469	16,504
Guaranty Obligation	135	135
Maximum Recovery	$ 2,707	$ 2,869
Minimum [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Remaining contractual terms of our guarantees	1 day
Maximum [Member]
Financial Guarantees and Maximum Recovery [Line Items]
Remaining contractual terms of our guarantees	36 years

Represents the original contractual term of guarantees.

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- Definition

[Line Items] for Financial Guarantees and Maximum Recovery [Table]

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No definition available.

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- Definition

The fair value of our guaranty obligations associated with the Fannie Mae MBS included in “Investments in securities”

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No definition available.

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- Definition

Represents the maximum amount we could recover through available credit enhancements and recourse with third parties on guarantees recognized in our on and off balance sheets. Recoverability of such credit enhancements and recourse is subject to, among other factors, our mortgage insurers' and financial guarantors' ability to meet their obligations to us.

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No definition available.

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- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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