Mortgage Loans TDRs with Sub Defaults (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017 USD ($) contracts	Jun. 30, 2016 USD ($) contracts	Jun. 30, 2017 USD ($) contracts	Jun. 30, 2016 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	5,029	5,720	10,343	12,291
Recorded investment troubled debt restructurings subsequent default \| $	$ 719	$ 797	$ 1,480	$ 1,794
Single-family [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts			10,342	12,291
Recorded investment troubled debt restructurings subsequent default \| $			$ 1,476	$ 1,794
Single-family [Member] \| Primary [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	4,238	4,648	8,717	10,109
Recorded investment troubled debt restructurings subsequent default \| $	$ 589	$ 638	$ 1,210	$ 1,440
Single-family [Member] \| Government [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	25	27	44	42
Recorded investment troubled debt restructurings subsequent default \| $	$ 3	$ 3	$ 5	$ 5
Single-family [Member] \| Alt-A [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	616	756	1,230	1,608
Recorded investment troubled debt restructurings subsequent default \| $	$ 97	$ 116	$ 193	$ 260
Single-family [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts	150	289	351	532
Recorded investment troubled debt restructurings subsequent default \| $	$ 30	$ 40	$ 68	$ 89
Multifamily [Member]
Financing Receivable, Modifications [Line Items]
Number of loans troubled debt restructurings subsequent default \| contracts			1	0
Recorded investment troubled debt restructurings subsequent default \| $			$ 4	$ 0

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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=66008989&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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