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Related Party Disclosures (Nephila) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Related Party Transaction [Line Items] |  |  |  |
Gross premium volume | $ 3,788,185 | $ 3,280,049 | $ 7,224,197 | $ 6,678,336
Premiums ceded | 1,580,492 | 1,180,254 | 2,798,726 | 2,413,807
Program services and other fronting [Member] | Nephila Reinsurers [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Gross premium volume | 297,393 | 175,185 | 534,288 | 490,772
Premiums ceded | 297,393 | 175,185 | 534,288 | 490,772
Underwriting [Member] | Nephila Reinsurers [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Premiums ceded | $ 16,384 | $ 13,512 | $ 29,847 | $ 29,619

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