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Municipal Bond Guarantee Insurance - Schedule of Municipal Guarantee Insurance Contracts, Premium Received Over Contract Period (Details) - BAM - USD ($) $ in Millions | Jun. 30, 2023 | Dec. 31, 2022
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Guarantor Obligations [Line Items] |  |
July 1, 2023 - December 31, 2023 | $ 14.2 |
January 1, 2024 - March 31, 2024 | 6.9 |
April 1, 2024 - June 30, 2024 | 6.9 |
July 1, 2024 - September 30, 2024 | 6.7 |
October 1, 2024 - December 31, 2024 | 6.6 |
Total 2024 | 27.1 |
2025 | 25.4 |
2026 | 23.7 |
2027 | 22.1 |
2028 | 20.4 |
2029 and thereafter | 170.8 |
Total gross unearned insurance premiums | $ 303.7 | $ 298.3

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