Mortgage Loans Individually Impaired Loans (Details) $ in Millions	Dec. 31, 2019 USD ($)
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	$ 79,696
Individually impaired loans with related allowance recorded: total recorded investment	76,543
Related allowance for loan losses	(8,220)
Individually impaired loans with no related allowance recorded: unpaid principal balance	22,424
Individually impaired loans with no related allowance recorded: total recorded investment	21,333
Total individually impaired loans: unpaid principal balance	102,120
Total individually impaired loans: total recorded investment	97,876
Single-Family [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	79,382
Individually impaired loans with related allowance recorded: total recorded investment	76,228
Related allowance for loan losses	(8,175)
Individually impaired loans with no related allowance recorded: unpaid principal balance	22,061
Individually impaired loans with no related allowance recorded: total recorded investment	20,968
Table Footnote [Abstract]
Troubled debt restructuring recorded investment	96,900
Single-Family [Member] \| Fixed Rate Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	63,091
Individually impaired loans with related allowance recorded: total recorded investment	61,033
Related allowance for loan losses	(5,851)
Individually impaired loans with no related allowance recorded: unpaid principal balance	18,372
Individually impaired loans with no related allowance recorded: total recorded investment	17,578
Single-Family [Member] \| FixedRateResidentialMortgage15yearMember [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	954
Individually impaired loans with related allowance recorded: total recorded investment	960
Related allowance for loan losses	(24)
Individually impaired loans with no related allowance recorded: unpaid principal balance	410
Individually impaired loans with no related allowance recorded: total recorded investment	407
Single-Family [Member] \| Adjustable Rate Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	156
Individually impaired loans with related allowance recorded: total recorded investment	157
Related allowance for loan losses	(9)
Individually impaired loans with no related allowance recorded: unpaid principal balance	265
Individually impaired loans with no related allowance recorded: total recorded investment	265
Single-Family [Member] \| Other [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	15,181
Individually impaired loans with related allowance recorded: total recorded investment	14,078
Related allowance for loan losses	(2,291)
Individually impaired loans with no related allowance recorded: unpaid principal balance	3,014
Individually impaired loans with no related allowance recorded: total recorded investment	2,718
Multifamily [Member]
Financing Receivable, Impaired [Line Items]
Individually impaired loans with related allowance recorded: unpaid principal balance	314
Individually impaired loans with related allowance recorded: total recorded investment	315
Related allowance for loan losses	(45)
Individually impaired loans with no related allowance recorded: unpaid principal balance	363
Individually impaired loans with no related allowance recorded: total recorded investment	365
Table Footnote [Abstract]
Troubled debt restructuring recorded investment	$ 102

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