Mortgage Loans Held for Portfolio (Mortgage Loans Held for Portfolio) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, before Fees, Gross	$ 14,453	$ 11,817
Financing Receivable, Accrued Interest, after Allowance for Credit Loss	14,540	11,896
Loans Receivable With Fixed Rates Of Interest Long Term [Member] \| Single Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, before Fees, Gross	13,549	10,961
Loans Receivable With Fixed Rates Of Interest Medium Term [Member] \| Single Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, before Fees, Gross	904	856
Residential Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, before Fees, Gross	14,453	11,817
Loans and Leases Receivable, Unamortized Premiums	156	130
Loans and Leases Receivable, Unamortized Discounts	(54)	(33)
Loans and Leases Receivable, Hedging Basis Adjustment	(9)	(13)
Financing Receivable, Past Due	14,546	11,901
Allowance for credit losses on mortgage loans	(6)	(5)
Financing Receivable, Accrued Interest, after Allowance for Credit Loss	$ 14,540	$ 11,896

Reflects the cumulative amount of hedging adjustments that are being amortized into income as an adjustment of yield.

No definition available.

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Balance Type:	debit
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- Definition

Reflects the cumulative amount of discounts from the face amount of loans that are being amortized into income as an adjustment of yield.

+ References

No definition available.

+ Details

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- Definition

Reflects the cumulative amount of premiums over the face amount of loans that are being amortized into income as an adjustment to yield.

+ References

No definition available.

+ Details

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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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, after allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

+ Details

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- Details

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- Details

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- Details

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- Details

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