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Reserves For Losses And Loss Expenses (Loss and Loss Expenses Incurred, Net of Reinsurance, and Cumulative Paid Claims and Claim Adjustment Expenses, Net of Reinsurance) (Details) $ in Thousands | Dec. 31, 2024 USD ($) claim | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
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Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | $ 17,571,201 |  |  |  |  |  |  |  |  |  |
Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 14,994,380 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 8,033,653 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 178,312 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 7,139,039 |  |  |  |  |  |  |  |  |  |
Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 6,924,123 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 5,352,614 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 246,975 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 1,818,484 |  |  |  |  |  |  |  |  |  |
Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 4,440,919 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 2,362,092 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 49,908 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 2,128,735 |  |  |  |  |  |  |  |  |  |
Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 6,068,948 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 4,414,794 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 2,295 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 1,656,449 |  |  |  |  |  |  |  |  |  |
Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 8,365,242 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 7,401,278 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 5,937 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 969,901 |  |  |  |  |  |  |  |  |  |
Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 3,804,431 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 1,994,684 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 357,939 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 2,167,686 |  |  |  |  |  |  |  |  |  |
Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 728,836 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 146,654 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 577,639 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 1,159,821 |  |  |  |  |  |  |  |  |  |
Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,707,893 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 1,359,406 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses before 2015, net of reinsurance | 1,971 |  |  |  |  |  |  |  |  |  |
Reserves for loss and loss adjustment expenses, net of reinsurance | 350,458 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,019,173 | $ 1,005,801 | $ 999,316 | $ 969,789 | $ 963,118 | $ 951,981 | $ 948,706 | $ 944,351 | $ 969,246 | $ 934,138 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 948,434 | 916,787 | 862,557 | 804,340 | 745,994 | 665,272 | 528,935 | 374,666 | 205,207 | 80,079 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 32,718 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 28,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 604,806 | 603,731 | 612,687 | 617,477 | 620,741 | 626,432 | 641,169 | 650,997 | 690,525 | 712,800 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 570,125 | 564,658 | 557,215 | 544,849 | 531,512 | 512,933 | 477,541 | 421,734 | 323,744 | 139,320 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 14,681 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 58,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 285,252 | 285,591 | 286,203 | 281,906 | 281,461 | 289,722 | 274,229 | 272,360 | 255,638 | 256,877 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 265,643 | 258,640 | 246,160 | 239,162 | 232,187 | 215,640 | 186,834 | 139,244 | 85,061 | 20,271 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 11,809 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 8,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 410,218 | 409,329 | 409,797 | 407,874 | 410,762 | 412,416 | 411,886 | 403,449 | 398,090 | 374,801 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 405,009 | 402,938 | 401,130 | 397,747 | 392,093 | 379,779 | 353,772 |  | 310,923 | 255,990 | $ 155,699
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 784 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 50,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 697,949 | 699,018 | 694,284 | 693,963 | 695,584 | 697,123 | 704,501 | 705,938 | 708,711 | 718,877 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 702,432 | 700,792 | 691,545 | 691,365 | 684,679 | 678,891 | 669,556 | 647,710 | 592,871 | 380,892 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 1,485 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 29,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 346,178 | 336,653 | 335,541 | 333,368 | 331,370 | 321,934 | 281,470 | 260,696 | 261,479 | 285,491 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 308,837 | 295,608 | 278,540 | 260,577 | 232,001 | 203,940 | 163,728 | 110,230 | 61,106 | 24,672 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 9,461 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 28,220 | 33,590 | 32,604 | 36,774 | 39,781 | 39,682 | 45,115 | 50,099 | 57,897 | 69,977 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 7,402 | 6,844 | 6,457 | 5,421 | 5,083 | 4,416 | 4,099 | 3,272 | 2,481 | 2,069 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 5,749 |  |  |  |  |  |  |  |  |  |
Accident Year 2014 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 146,485 | 146,893 | 146,346 | 145,697 | 146,140 | 144,486 | 145,422 | 146,437 | 132,570 | 141,484 |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 144,369 | 143,999 | 143,103 | 141,963 | 140,564 | 137,708 | 133,605 | 123,995 | 103,634 | 64,495 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 444 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,122,233 | 1,121,260 | 1,079,436 | 1,048,121 | 1,032,281 | 1,018,025 | 1,005,560 | 995,148 | 1,003,192 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 996,649 | 944,014 | 860,423 | 757,110 | 667,761 | 550,589 | 383,909 | 203,890 | 67,290 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 59,052 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 29,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 639,412 | 641,549 | 654,385 | 657,972 | 651,278 | 660,520 | 684,700 | 696,339 | 702,716 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 591,005 | 584,330 | 572,669 | 558,934 | 537,861 | 504,850 | 446,072 | 338,835 | 142,998 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 15,340 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 58,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 452,769 | 449,033 | 462,868 | 467,183 | 437,690 | 400,178 | 359,228 | 322,107 | 307,902 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 421,639 | 412,243 | 404,669 | 356,717 | 296,742 | 254,694 | 200,949 | 102,079 | 28,432 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 15,280 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 10,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 425,280 | 426,814 | 425,063 | 423,171 | 423,216 | 426,365 | 425,808 | 415,208 | 414,205 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 421,309 | 418,672 | 412,624 | 404,241 | 394,720 | 375,891 | 330,222 |  | 270,304 | $ 178,350 |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 1,648 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 48,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 732,544 | 734,306 | 733,993 | 735,299 | 732,853 | 738,577 | 744,208 | 756,684 | 752,238 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 727,943 | 725,721 | 720,716 | 719,883 | 713,193 | 708,340 | 693,535 | 652,336 | 403,529 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 1,814 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 31,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 332,140 | 328,079 | 332,538 | 325,590 | 325,777 | 292,188 | 269,643 | 277,255 | 265,059 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 279,490 | 267,375 | 249,017 | 228,163 | 193,167 | 159,651 | 115,017 | 73,546 | 26,599 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 12,449 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 55,371 | 59,804 | 63,932 | 65,222 | 65,485 | 64,957 | 71,404 | 70,281 | 72,657 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 16,872 | 13,569 | 11,819 | 9,883 | 7,685 | 5,928 | 5,573 | 4,783 | 2,498 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 5,800 |  |  |  |  |  |  |  |  |  |
Accident Year 2015 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 203,198 | 204,190 | 203,070 | 201,996 | 204,004 | 198,523 | 198,909 | 191,947 | 185,533 |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 202,409 | 201,985 | 200,070 | 195,736 | 193,595 | 185,937 | 174,449 | 150,326 | 91,514 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 781 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,289,349 | 1,256,832 | 1,238,759 | 1,169,138 | 1,129,392 | 1,111,550 | 1,088,787 | 1,055,253 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 1,119,123 | 1,038,695 | 922,090 | 767,665 | 632,721 | 447,743 | 251,172 | 77,719 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 79,218 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 28,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 669,988 | 675,871 | 682,153 | 683,880 | 673,216 | 689,622 | 733,505 | 762,093 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 617,243 | 603,006 | 583,258 | 559,198 | 525,753 | 468,817 | 362,299 | 153,456 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 15,800 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 58,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 401,789 | 401,170 | 392,447 | 383,246 | 376,096 | 337,256 | 330,753 | 331,362 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 349,406 | 329,021 | 306,270 | 260,764 | 242,696 | 162,469 | 96,025 | 36,381 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 26,447 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 11,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 429,646 | 428,064 | 427,474 | 423,180 | 417,010 | 412,760 | 410,409 | 412,917 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 421,898 | 414,033 | 403,421 | 385,822 | 356,864 | 314,336 | 256,952 |  | $ 173,668 |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 2,931 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 44,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 722,138 | 722,551 | 723,925 | 722,697 | 722,967 | 723,989 | 729,675 | 730,239 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 725,516 | 723,111 | 717,788 | 710,624 | 707,472 | 695,566 | 667,750 | 429,132 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 2,262 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 39,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 344,072 | 334,003 | 320,518 | 304,542 | 285,053 | 263,327 | 245,631 | 255,303 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 269,239 | 233,096 | 198,517 | 169,379 | 143,838 | 86,509 | 54,395 | 25,295 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 19,683 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 57,073 | 62,213 | 65,147 | 66,795 | 71,025 | 70,749 | 80,508 | 76,701 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 23,523 | 21,275 | 19,275 | 18,375 | 17,327 | 15,356 | 12,810 | 6,282 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 8,242 |  |  |  |  |  |  |  |  |  |
Accident Year 2016 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 215,714 | 216,854 | 215,723 | 215,295 | 221,413 | 222,463 | 223,315 | 227,950 |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 212,577 | 211,837 | 209,232 | 206,018 | 202,436 | 194,150 | 162,814 | $ 87,892 |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 347 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,374,348 | 1,291,745 | 1,225,588 | 1,148,972 | 1,113,675 | 1,123,152 | 1,095,529 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 1,122,768 | 979,311 | 801,409 | 611,323 | 432,148 | 261,789 | 85,148 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 98,378 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 28,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 708,336 | 715,018 | 721,170 | 724,056 | 715,055 | 724,697 | 778,964 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 660,237 | 642,292 | 613,675 | 574,889 | 508,546 | 397,464 | 171,006 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 14,769 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 56,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 393,029 | 397,102 | 381,613 | 358,676 | 332,201 | 320,784 | 333,254 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 315,361 | 283,349 | 243,813 | 198,351 | 154,953 | 99,433 | 28,072 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 59,723 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 11,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 513,458 | 511,283 | 502,221 | 474,469 | 459,826 | 443,203 | 423,120 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 493,942 | 479,144 | 445,527 | 397,517 | 337,599 | 272,020 | 173,779 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 5,358 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 43,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 718,987 | 723,401 | 724,399 | 726,956 | 728,426 | 731,643 | 741,002 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 715,238 | 712,526 | 707,471 | 708,449 | 691,499 | 645,228 | 401,547 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 4,803 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 46,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 327,489 | 310,129 | 282,547 | 270,699 | 254,696 | 235,054 | 245,491 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 245,037 | 207,435 | 163,823 | 128,691 | 93,211 | 52,668 | 18,921 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 26,167 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 54,784 | 58,244 | 60,347 | 66,180 | 71,448 | 72,505 | 77,820 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 14,952 | 13,583 | 12,414 | 10,359 | 9,368 | 8,230 | 6,141 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 14,257 |  |  |  |  |  |  |  |  |  |
Accident Year 2017 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 117,569 | 118,633 | 120,254 | 121,985 | 120,284 | 128,611 | 125,574 |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 114,035 | 113,418 | 112,061 | 103,833 | 98,416 | 80,976 | $ 46,892 |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 918 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,396,012 | 1,362,171 | 1,286,835 | 1,230,016 | 1,228,679 | 1,232,661 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 1,073,894 | 902,686 | 699,906 | 467,267 | 271,854 | 86,531 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 139,046 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 30,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 714,086 | 722,456 | 734,034 | 732,762 | 721,018 | 784,281 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 644,772 | 618,324 | 581,003 | 515,914 | 397,376 | 184,715 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 18,751 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 54,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 364,231 | 362,333 | 353,131 | 344,036 | 330,146 | 334,137 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 270,623 | 234,789 | 199,942 | 147,500 | 97,082 | 31,563 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 62,324 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 12,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 532,292 | 525,110 | 508,501 | 483,438 | 465,817 | 462,866 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 499,996 | 473,940 | 423,225 | 360,921 | 279,858 | 179,847 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 9,383 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 43,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 658,367 | 668,628 | 668,632 | 674,717 | 684,671 | 703,177 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 651,960 | 649,886 | 641,809 | 629,427 | 600,257 | 392,083 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 4,744 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 41,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 315,025 | 294,105 | 265,001 | 264,664 | 257,452 | 260,178 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 219,777 | 170,169 | 116,579 | 81,222 | 52,609 | 21,506 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 35,101 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 70,929 | 73,571 | 76,478 | 76,242 | 77,482 | 78,929 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 21,094 | 18,836 | 15,436 | 12,728 | 10,884 | 6,241 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 13,613 |  |  |  |  |  |  |  |  |  |
Accident Year 2018 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 95,708 | 96,575 | 96,681 | 97,748 | 93,038 | 119,838 |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 90,550 | 88,628 | 86,633 | 83,990 | 69,694 | $ 35,563 |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 1,282 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,187,560 | 1,157,392 | 1,148,852 | 1,204,248 | 1,330,660 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 812,453 | 614,351 | 417,860 | 222,274 | 70,540 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 181,892 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 24,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 652,424 | 668,222 | 704,008 | 716,430 | 725,245 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 579,332 | 548,585 | 485,203 | 380,454 | 172,478 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 12,026 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 42,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 299,806 | 312,169 | 336,231 | 373,550 | 391,532 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 196,332 | 168,670 | 128,579 | 79,968 | 27,895 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 56,121 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 11,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 440,625 | 433,980 | 407,515 | 396,616 | 493,527 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 402,177 | 346,892 | 285,875 | 213,638 | 136,899 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 5,170 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 29,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 912,987 | 909,800 | 905,858 | 887,821 | 882,508 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 888,746 | 884,460 | 829,586 | 768,617 | 447,105 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 3,715 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 36,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 345,540 | 346,355 | 327,257 | 329,319 | 333,743 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 217,958 | 171,527 | 109,396 | 66,937 | 28,291 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 62,760 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 70,219 | 80,946 | 82,952 | 83,468 | 84,354 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 15,427 | 12,869 | 10,471 | 8,699 | 4,869 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 23,018 |  |  |  |  |  |  |  |  |  |
Accident Year 2019 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 136,155 | 137,504 | 132,670 | 133,897 | 131,649 |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 118,503 | 111,508 | 102,593 | 81,238 | $ 39,652 |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 844 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,352,616 | 1,332,486 | 1,378,751 | 1,522,682 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 794,392 | 484,588 | 265,080 | 75,101 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 285,076 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 26,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 649,222 | 667,517 | 701,703 | 742,687 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 547,863 | 490,648 | 384,867 | 172,729 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 22,916 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 46,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 408,536 | 444,060 | 468,567 | 521,744 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 219,932 | 152,764 | 85,661 | 28,465 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 119,166 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 12,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 583,693 | 552,219 | 517,233 | 552,002 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 476,462 | 379,966 | 289,016 | 168,497 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 26,200 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 35,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 790,478 | 793,394 | 809,924 | 805,048 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 755,877 | 732,996 | 677,015 | 388,917 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 11,207 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 33,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 423,874 | 421,190 | 428,105 | 425,922 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 211,884 | 145,859 | 76,977 | 24,649 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 118,203 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 84,681 | 89,220 | 90,980 | 98,110 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 11,412 | 8,872 | 6,026 | 4,586 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 27,325 |  |  |  |  |  |  |  |  |  |
Accident Year 2020 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 161,699 | 165,760 | 168,265 | 156,046 |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 145,315 | 130,371 | 92,579 | $ 31,624 |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 2,766 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 1,798,403 | 1,815,653 | 1,810,560 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 704,307 | 352,886 | 92,248 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 688,730 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 28,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 715,578 | 745,218 | 772,620 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 527,145 | 408,929 | 180,982 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 56,385 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 46,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 553,174 | 582,764 | 644,950 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 160,965 | 90,416 | 33,336 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 307,294 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 12,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 763,806 | 740,688 | 723,266 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 531,324 | 394,136 | 237,885 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 83,225 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 41,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 880,040 | 889,173 | 904,554 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 827,552 | 761,924 | 440,856 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 25,611 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 31,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 474,466 | 501,517 | 488,982 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 159,100 | 83,590 | 28,029 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 208,624 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 100,612 | 101,725 | 128,923 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 17,778 | 10,564 | 5,898 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 26,481 |  |  |  |  |  |  |  |  |  |
Accident Year 2021 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 202,600 | 205,569 | 205,886 |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 152,174 | 128,640 | $ 56,483 |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 24,379 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 2,075,065 | 2,111,178 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 366,496 | 91,733 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 1,312,841 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 25,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 758,657 | 784,906 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 418,788 | 195,204 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 146,880 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 45,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 634,269 | 642,582 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 121,991 | 40,973 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 404,820 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 13,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 907,503 | 890,682 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 467,227 | 271,552 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 226,458 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 43,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 997,176 | 1,035,378 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 846,828 | 531,838 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 66,732 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 28,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 466,192 | 472,810 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 66,568 | 17,622 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 305,158 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 86,901 | 110,446 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 12,471 | 6,390 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 41,059 |  |  |  |  |  |  |  |  |  |
Accident Year 2022 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 172,995 | 176,457 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 110,095 | $ 58,316 |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 37,096 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Other liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 2,379,621 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 95,137 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 2,070,647 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 18,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Workers' compensation |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 811,614 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 196,104 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 378,116 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 46,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Professional liability |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 648,064 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 40,200 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 499,645 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 13,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Auto |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 1,062,427 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 295,450 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 569,636 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 41,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Short-tail lines |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 1,254,576 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 559,186 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 450,792 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contract, cumulative number of reported claims | claim | 24,000 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Casualty |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | $ 429,455 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 16,794 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 382,444 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Monoline excess |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 120,046 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 5,723 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | 98,632 |  |  |  |  |  |  |  |  |  |
Accident Year 2023 | Property |  |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loss and loss expenses incurred, net of reinsurance | 255,770 |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim adjustment expenses, net of reinsurance | 69,379 |  |  |  |  |  |  |  |  |  |
Short-duration insurance contracts, incurred but not reported (IBNR) claims liability, net | $ 137,881 |  |  |  |  |  |  |  |  |  |

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