Mortgage Loans Held for Portfolio (Mortgage Loans Held for Portfolio by Collateral or Guarantee Type) (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Loans and Leases Receivable, before Fees, Gross | $ 15,452 | $ 14,453 |
| US Government Agency Insured Loans [Member] | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Loans and Leases Receivable, before Fees, Gross | 343 | 356 |
| Conventional Mortgage Loan [Member] | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Loans and Leases Receivable, before Fees, Gross | $ 15,109 | $ 14,097 |