Mortgage Loans Held for Portfolio (Payment Status) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Financial Asset, Past Due \| Conventional Mortgage Loan [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Accrued Interest, before Allowance for Credit Loss	$ 136	$ 146

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.

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