Advances by Counterparty Concentration (Details) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Concentration Risk [Line Items]
Par value	$ 62,923	$ 56,454
Credit Concentration Risk \| The Northern Trust Company
Concentration Risk [Line Items]
Par value	$ 8,500
Credit Concentration Risk \| The Northern Trust Company \| Federal Home Loan Bank of Chicago Advances
Concentration Risk [Line Items]
% of Total Outstanding	13.50%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-42

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 825
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-21

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 825
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 275
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-Section 50
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-20

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