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Outstanding Exposure - Components of BIG Net Par Outstanding (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | $ 261,552 | $ 249,153
Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 250,375 | 239,296
Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 9,670 | 8,083
Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 11,177 | 9,857
U.S. |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 209,628 |
U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 201,175 | 190,289
U.S. | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 1,507 | 1,774
U.S. | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 8,453 | 8,632
Non U.S. |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 51,924 |
Non U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 49,200 | 49,007
Non U.S. | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 2,724 | 1,225
BIG |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 10,182 | 5,437
BIG | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 9,286 | 4,402
BIG | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 77 | 94
BIG | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 896 | 1,035
BIG | U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 2,888 | 3,271
BIG | U.S. | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 819 | 941
BIG | U.S. | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 896 | 1,035
BIG | Non U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 6,398 | 1,131
BIG | Non U.S. | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 0 | 0
BIG | BIG 1 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 8,102 | 2,410
BIG | BIG 1 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 7,998 | 2,388
BIG | BIG 1 | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 0 | 0
BIG | BIG 1 | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 104 | 22
BIG | BIG 1 | U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 2,119 | 1,257
BIG | BIG 1 | U.S. | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 104 | 22
BIG | BIG 1 | Non U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 5,879 | 1,131
BIG | BIG 2 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 706 | 989
BIG | BIG 2 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 656 | 926
BIG | BIG 2 | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 21 | 27
BIG | BIG 2 | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 50 | 63
BIG | BIG 2 | U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 137 | 926
BIG | BIG 2 | U.S. | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 29 | 36
BIG | BIG 2 | Non U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 519 | 0
BIG | BIG 3 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 1,374 | 2,038
BIG | BIG 3 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 632 | 1,088
BIG | BIG 3 | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 56 | 67
BIG | BIG 3 | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 742 | 950
BIG | BIG 3 | U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 632 | 1,088
BIG | BIG 3 | U.S. | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | 686 | 883
BIG | BIG 3 | Non U.S. | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net Par Outstanding | $ 0 | $ 0

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