Contracts Accounted for as Financial Guaranty Insurance - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) - USD ($) $ in Millions |
6 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Gross Premium Receivable Net of Ceding Commissions [Roll Forward] | ||
| Beginning of year | $ 1,572 | $ 1,551 |
| Less: Specialty insurance premium receivable | 2 | 1 |
| Financial guaranty insurance premiums receivable | 1,570 | 1,550 |
| New business and supplemental premiums, net of commissions | 153 | 124 |
| Gross premiums received, net of commissions | (180) | (154) |
| Adjustments: | ||
| Changes in the expected term and debt service assumptions | (6) | (7) |
| Accretion of discount, net of commissions on assumed business | 11 | 17 |
| Foreign exchange gain (loss) on remeasurement | (23) | 101 |
| Change in allowance for credit losses | (4) | (1) |
| Financial guaranty insurance premiums receivable | 1,521 | 1,630 |
| Specialty insurance premium receivable | 2 | 1 |
| Ending balance | $ 1,523 | $ 1,631 |