Commitments and Contingencies - Commitments to Extend Credit on Lines of Credit and to Purchase First Mortgages (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Total | $ 3,566 | $ 2,718 |
| Commitments to extend credit related to unused HELOCs and other lines of credit | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Commitments to extend credit related to unused HELOCs and other lines of credit | 1,852 | 1,793 |
| Residential real estate | First Mortgages | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Commitments to purchase First Mortgage loans | $ 1,714 | $ 925 |