Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans in Mortgage Portfolio [Line Items]
Unpaid principal balance of mortgage loans	$ 3,299,954	$ 3,223,783
Cost basis and fair value adjustments, net	43,224	39,815
Allowance for loan losses for loans held for investment	(9,016)	(14,203)	$ (19,084)	$ (23,465)
Total mortgage loans	3,334,162	3,249,395
Carrying value of loans redesignated from HFI to HFS	17,126	21,960	12,886
Carrying value of loans redesignated from HFS to HFI	28	56	113
Sale of loans, unpaid principal balance	19,737	21,918	12,184
Realized gains on sales of mortgage loans	1,238	444	$ 723
Single-Family [Member]
Loans in Mortgage Portfolio [Line Items]
Unpaid principal balance of mortgage loans	2,972,361	2,929,925
Recorded investment of single-family mortgage loans referred to foreclosure	7,600	10,100
Multifamily [Member]
Loans in Mortgage Portfolio [Line Items]
Unpaid principal balance of mortgage loans	$ 327,593	$ 293,858

The amount of financing receivable to held-for-investment during the reporting period.

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- 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.

+ References

No definition available.

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Represents premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield and fair value adjustments.

+ References

No definition available.

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- Definition

Represents principal amount outstanding of mortgage loans.

+ References

No definition available.

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- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 4
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- Definition

Amount of financing receivable reclassified to held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
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Amount of decrease from sale and reclassification to held-for-sale of financing receivable.

+ References

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- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

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-Publisher FASB
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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

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- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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