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Municipal Bond Guarantee Insurance - Schedule of Municipal Bond Guarantee Insured Obligations (Details) - BAM $ in Millions | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2022 USD ($) Contract | Dec. 31, 2021 USD ($) Contract | Sep. 01, 2022 USD ($) | Jan. 31, 2021 USD ($)
Guarantor Obligations [Line Items] |  |  |  |
Contracts outstanding | Contract | 13,094 | 12,350 |  |
Remaining weighted average contract period outstanding (in years) | 10 years 9 months 18 days | 10 years 9 months 18 days |  |
Principal | $ 98,619.0 | $ 89,196.5 | $ 42.5 | $ 805.5
Interest | 47,595.0 | 41,486.5 |  |
Total debt service outstanding | 146,214.0 | 130,683.0 |  |
Total gross unearned insurance premiums | $ 286.7 | $ 266.3 |  |

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