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Outstanding Exposure - Components of BIG Net Par Outstanding (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Schedule of Insured Financial Obligations [Line Items] |  |
Net | $ 248,144 | $ 249,153
Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 238,132 | 239,296
Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 8,328 | 8,083
Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 10,012 | 9,857
BIG |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 5,193 | 5,437
BIG | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 4,224 | 4,402
BIG | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 91 | 94
BIG | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 969 | 1,035
BIG | BIG 1 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 2,371 | 2,410
BIG | BIG 1 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 2,354 | 2,388
BIG | BIG 1 | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 0 | 0
BIG | BIG 1 | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 17 | 22
BIG | BIG 2 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 987 | 989
BIG | BIG 2 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 926 | 926
BIG | BIG 2 | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 25 | 27
BIG | BIG 2 | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 61 | 63
BIG | BIG 3 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 1,835 | 2,038
BIG | BIG 3 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 944 | 1,088
BIG | BIG 3 | Other structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 66 | 67
BIG | BIG 3 | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 891 | 950
United States | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 189,895 | 190,289
United States | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 1,684 | 1,774
United States | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 8,643 | 8,632
United States | BIG | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 3,119 | 3,271
United States | BIG | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 878 | 941
United States | BIG | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 969 | 1,035
United States | BIG | BIG 1 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 1,249 | 1,257
United States | BIG | BIG 1 | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 17 | 22
United States | BIG | BIG 2 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 926 | 926
United States | BIG | BIG 2 | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 36 | 36
United States | BIG | BIG 3 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 944 | 1,088
United States | BIG | BIG 3 | RMBS |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 825 | 883
Non-U.S. public finance | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 48,237 | 49,007
Non-U.S. public finance | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 1,369 | 1,225
Non-U.S. public finance | BIG | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 1,105 | 1,131
Non-U.S. public finance | BIG | Structured finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 0 | 0
Non-U.S. public finance | BIG | BIG 1 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 1,105 | 1,131
Non-U.S. public finance | BIG | BIG 2 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | 0 | 0
Non-U.S. public finance | BIG | BIG 3 | Public finance |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net | $ 0 | $ 0

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