Mortgage Loans TDRs with Sub Defaults (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016 USD ($) contracts	Jun. 30, 2015 USD ($) contracts	Jun. 30, 2016 USD ($) contracts	Jun. 30, 2015 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	5,720	7,447	12,291	15,649
Recorded investment troubled debt restructurings subsequent default \| $	$ 797	$ 1,078	$ 1,794	$ 2,357
Single-family [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	5,720	7,446	12,291	15,646
Recorded investment troubled debt restructurings subsequent default \| $	$ 797	$ 1,076	$ 1,794	$ 2,351
Single-family [Member] \| Primary [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	4,648	6,156	10,109	12,879
Recorded investment troubled debt restructurings subsequent default \| $	$ 638	$ 864	$ 1,440	$ 1,867
Single-family [Member] \| Government [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	27	37	42	57
Recorded investment troubled debt restructurings subsequent default \| $	$ 3	$ 6	$ 5	$ 9
Single-family [Member] \| Alt-A [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	756	963	1,608	2,116
Recorded investment troubled debt restructurings subsequent default \| $	$ 116	$ 151	$ 260	$ 354
Single-family [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	289	290	532	594
Recorded investment troubled debt restructurings subsequent default \| $	$ 40	$ 55	$ 89	$ 121
Multifamily [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	0	1	0	3
Recorded investment troubled debt restructurings subsequent default \| $	$ 0	$ 2	$ 0	$ 6

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953682-111524

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Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

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