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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2022 | Mar. 31, 2021
Premiums earned: |  |
Net | $ 812,283 | $ 724,960
Loss and loss expenses incurred: |  |
Net | 494,236 | 413,401
Direct Assumed and Ceded Reinsurance Amounts [Member] |  |
Premiums written: |  |
Direct | 1,001,049 | 908,774
Assumed | 5,314 | 5,533
Ceded | (116,565) | (116,129)
Net | 889,798 | 798,178
Premiums earned: |  |
Direct | 931,376 | 837,369
Assumed | 5,528 | 5,676
Ceded | (124,621) | (118,085)
Net | 812,283 | 724,960
Loss and loss expenses incurred: |  |
Direct | 528,588 | 441,507
Assumed | 4,278 | 3,447
Ceded | (38,630) | (31,553)
Net | $ 494,236 | $ 413,401

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