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RESERVE FOR LOSSES AND LOSS EXPENSES - Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance (Details) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
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Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | $ 8,676,295 |  |  |  |  |  |  |  |  |
Insurance |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 3,540,908 |  |  |  |  |  |  |  |  |
Insurance | Property and other |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 2,817,520 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 5,862 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 771,659 |  |  |  |  |  |  |  |  |
Insurance | Property and other | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 77,252 | $ 77,248 | $ 76,980 | $ 76,673 | $ 74,453 | $ 73,387 | $ 72,499 | $ 68,653 | $ 60,085 | $ 31,360
Insurance | Property and other | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 110,171 | 109,837 | 109,794 | 110,008 | 109,933 | 105,719 | 94,912 | 86,886 | 48,575 |
Insurance | Property and other | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 270,946 | 270,666 | 269,994 | 270,309 | 271,451 | 249,162 | 192,892 | 84,811 |  |
Insurance | Property and other | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 312,894 | 312,818 | 307,639 | 300,129 | 277,230 | 213,138 | 77,088 |  |  |
Insurance | Property and other | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 261,266 | 258,435 | 247,393 | 236,405 | 197,898 | 75,214 |  |  |  |
Insurance | Property and other | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 315,797 | 311,730 | 304,609 | 258,098 | 131,991 |  |  |  |  |
Insurance | Property and other | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 239,989 | 225,593 | 201,166 | 98,366 |  |  |  |  |  |
Insurance | Property and other | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 327,706 | 287,049 | 122,407 |  |  |  |  |  |  |
Insurance | Property and other | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 625,027 | 251,358 |  |  |  |  |  |  |  |
Insurance | Property and other | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 276,472 |  |  |  |  |  |  |  |  |
Insurance | Marine |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 588,505 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 8,619 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 340,668 |  |  |  |  |  |  |  |  |
Insurance | Marine | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 50,244 | 48,920 | 48,587 | 48,321 | 45,775 | 45,159 | 43,147 | 39,674 | 30,297 | 17,394
Insurance | Marine | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 43,433 | 43,346 | 46,940 | 45,976 | 45,194 | 42,364 | 33,298 | 28,631 | 18,029 |
Insurance | Marine | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 66,913 | 64,868 | 60,572 | 59,862 | 58,025 | 54,930 | 44,218 | 26,435 |  |
Insurance | Marine | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 54,721 | 52,724 | 50,331 | 49,523 | 44,800 | 38,545 | 10,711 |  |  |
Insurance | Marine | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 76,856 | 65,822 | 63,128 | 54,898 | 44,087 | 18,982 |  |  |  |
Insurance | Marine | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 35,987 | 26,924 | 26,838 | 15,172 | 6,349 |  |  |  |  |
Insurance | Marine | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 111,027 | 108,152 | 54,869 | 21,426 |  |  |  |  |  |
Insurance | Marine | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 57,745 | 31,981 | 12,486 |  |  |  |  |  |  |
Insurance | Marine | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 68,563 | 14,472 |  |  |  |  |  |  |  |
Insurance | Marine | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 23,016 |  |  |  |  |  |  |  |  |
Insurance | Aviation |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 178,160 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 8,362 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 91,404 |  |  |  |  |  |  |  |  |
Insurance | Aviation | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 13,616 | 13,665 | 13,700 | 14,203 | 14,266 | 13,902 | 12,780 | 7,026 | 3,583 | 2,081
Insurance | Aviation | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 8,423 | 8,221 | 8,113 | 7,670 | 7,551 | 6,886 | 6,312 | 4,131 | 1,037 |
Insurance | Aviation | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 6,188 | 6,042 | 5,811 | 5,562 | 5,028 | 4,512 | 2,822 | 638 |  |
Insurance | Aviation | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 7,263 | 7,146 | 6,822 | 5,941 | 4,147 | 2,858 | 953 |  |  |
Insurance | Aviation | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 14,200 | 13,594 | 11,444 | 9,746 | 7,326 | 4,399 |  |  |  |
Insurance | Aviation | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 14,824 | 14,167 | 11,687 | 8,019 | 3,987 |  |  |  |  |
Insurance | Aviation | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 23,797 | 21,507 | 16,155 | 8,084 |  |  |  |  |  |
Insurance | Aviation | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 27,120 | 20,113 | 10,407 |  |  |  |  |  |  |
Insurance | Aviation | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 41,671 | 22,512 |  |  |  |  |  |  |  |
Insurance | Aviation | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 21,058 |  |  |  |  |  |  |  |  |
Insurance | Credit and political risk |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 600,313 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | (1,475) |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 99,011 |  |  |  |  |  |  |  |  |
Insurance | Credit and political risk | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 340,785 | 341,231 | 345,567 | 345,520 | 345,521 | 341,577 | 346,221 | 346,254 | 344,652 | 92,842
Insurance | Credit and political risk | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 102,514 | 102,196 | 102,154 | 101,948 | 101,786 | 106,767 | 90,729 | 85,418 | 50,000 |
Insurance | Credit and political risk | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 27,631 | 27,631 | 27,636 | 27,636 | 27,636 | 27,636 | 37,205 | 32,788 |  |
Insurance | Credit and political risk | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 42 | 39 | 38 | 0 | 0 | 0 | 0 |  |  |
Insurance | Credit and political risk | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 13,826 | 11,768 | 5,216 | 3,726 | 2,235 | 745 |  |  |  |
Insurance | Credit and political risk | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 57,855 | 57,855 | 61,108 | 39,952 | 1,924 |  |  |  |  |
Insurance | Credit and political risk | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 23,298 | 23,298 | 23,309 | 0 |  |  |  |  |  |
Insurance | Credit and political risk | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 24,479 | 24,445 | 0 |  |  |  |  |  |  |
Insurance | Credit and political risk | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 5,589 | 1,504 |  |  |  |  |  |  |  |
Insurance | Credit and political risk | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 4,294 |  |  |  |  |  |  |  |  |
Insurance | Professional lines |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 1,756,498 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 45,848 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 1,587,696 |  |  |  |  |  |  |  |  |
Insurance | Professional lines | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 184,577 | 177,492 | 165,088 | 126,542 | 106,985 | 96,631 | 68,690 | 44,065 | 20,619 | 1,657
Insurance | Professional lines | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 136,252 | 114,710 | 109,668 | 99,082 | 88,585 | 72,554 | 53,458 | 27,815 | 7,850 |
Insurance | Professional lines | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 294,043 | 282,907 | 237,804 | 165,206 | 107,980 | 73,940 | 32,812 | 7,399 |  |
Insurance | Professional lines | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 272,298 | 252,937 | 229,932 | 183,295 | 99,486 | 41,021 | 7,801 |  |  |
Insurance | Professional lines | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 241,074 | 211,931 | 174,759 | 128,858 | 72,784 | 17,633 |  |  |  |
Insurance | Professional lines | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 222,692 | 191,437 | 129,160 | 70,266 | 23,450 |  |  |  |  |
Insurance | Professional lines | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 168,627 | 137,145 | 67,313 | 19,976 |  |  |  |  |  |
Insurance | Professional lines | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 146,342 | 70,947 | 15,846 |  |  |  |  |  |  |
Insurance | Professional lines | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 71,495 | 20,812 |  |  |  |  |  |  |  |
Insurance | Professional lines | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 19,098 |  |  |  |  |  |  |  |  |
Insurance | Liability |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 601,478 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 43,840 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 650,470 |  |  |  |  |  |  |  |  |
Insurance | Liability | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 86,231 | 84,975 | 83,991 | 44,105 | 41,322 | 31,865 | 26,754 | 13,305 | 4,646 | 726
Insurance | Liability | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 87,981 | 86,433 | 71,788 | 66,114 | 61,029 | 53,581 | 30,788 | 15,966 | 1,030 |
Insurance | Liability | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 62,152 | 60,263 | 54,996 | 46,074 | 38,376 | 20,190 | 10,540 | 2,761 |  |
Insurance | Liability | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 46,545 | 42,745 | 37,139 | 30,145 | 15,411 | 5,514 | 1,630 |  |  |
Insurance | Liability | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 66,976 | 60,017 | 42,051 | 33,320 | 23,281 | 2,360 |  |  |  |
Insurance | Liability | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 84,397 | 71,617 | 49,840 | 18,645 | 1,415 |  |  |  |  |
Insurance | Liability | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 92,557 | 39,557 | 22,308 | 5,438 |  |  |  |  |  |
Insurance | Liability | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 36,406 | 23,286 | 6,318 |  |  |  |  |  |  |
Insurance | Liability | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 29,529 | 5,404 |  |  |  |  |  |  |  |
Insurance | Liability | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 8,704 |  |  |  |  |  |  |  |  |
Reinsurance |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 5,135,387 |  |  |  |  |  |  |  |  |
Reinsurance | Property and other |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 4,939,078 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 11,126 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 1,393,776 |  |  |  |  |  |  |  |  |
Reinsurance | Property and other | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 190,174 | 191,900 | 192,728 | 191,046 | 188,240 | 188,919 | 178,388 | 160,284 | 129,397 | 56,420
Reinsurance | Property and other | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 542,909 | 540,616 | 534,893 | 510,061 | 481,009 | 435,155 | 403,566 | 310,268 | 116,143 |
Reinsurance | Property and other | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 1,013,191 | 1,010,611 | 995,795 | 922,456 | 893,041 | 793,972 | 587,390 | 251,538 |  |
Reinsurance | Property and other | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 415,831 | 413,789 | 404,019 | 389,461 | 367,055 | 294,436 | 122,688 |  |  |
Reinsurance | Property and other | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 482,114 | 480,712 | 470,990 | 440,804 | 324,443 | 107,085 |  |  |  |
Reinsurance | Property and other | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 458,032 | 451,890 | 434,354 | 352,361 | 101,937 |  |  |  |  |
Reinsurance | Property and other | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 400,615 | 368,360 | 265,569 | 71,244 |  |  |  |  |  |
Reinsurance | Property and other | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 519,223 | 375,374 | 126,404 |  |  |  |  |  |  |
Reinsurance | Property and other | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 722,835 | 252,008 |  |  |  |  |  |  |  |
Reinsurance | Property and other | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 194,154 |  |  |  |  |  |  |  |  |
Reinsurance | Credit and surety |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 889,415 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 13,274 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 325,491 |  |  |  |  |  |  |  |  |
Reinsurance | Credit and surety | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 87,238 | 87,594 | 87,089 | 87,180 | 87,047 | 84,401 | 80,574 | 78,378 | 76,440 | 32,479
Reinsurance | Credit and surety | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 66,023 | 65,724 | 64,710 | 63,279 | 62,144 | 60,452 | 59,776 | 48,715 | 28,218 |
Reinsurance | Credit and surety | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 89,004 | 87,571 | 85,242 | 83,036 | 78,477 | 70,850 | 54,012 | 22,449 |  |
Reinsurance | Credit and surety | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 112,118 | 110,844 | 109,073 | 105,551 | 99,705 | 85,701 | 49,631 |  |  |
Reinsurance | Credit and surety | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 108,062 | 106,202 | 98,517 | 91,902 | 77,059 | 32,447 |  |  |  |
Reinsurance | Credit and surety | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 103,272 | 95,675 | 86,539 | 61,440 | 35,570 |  |  |  |  |
Reinsurance | Credit and surety | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 117,594 | 100,464 | 82,174 | 32,935 |  |  |  |  |  |
Reinsurance | Credit and surety | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 92,788 | 73,603 | 42,069 |  |  |  |  |  |  |
Reinsurance | Credit and surety | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 74,341 | 37,311 |  |  |  |  |  |  |  |
Reinsurance | Credit and surety | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 38,975 |  |  |  |  |  |  |  |  |
Reinsurance | Professional lines |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 911,479 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 47,397 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 1,039,085 |  |  |  |  |  |  |  |  |
Reinsurance | Professional lines | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 150,811 | 143,732 | 138,247 | 128,071 | 108,373 | 83,703 | 63,066 | 32,306 | 8,588 | 914
Reinsurance | Professional lines | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 137,917 | 130,487 | 123,889 | 107,270 | 76,763 | 52,129 | 31,245 | 12,029 | 1,758 |
Reinsurance | Professional lines | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 129,920 | 119,643 | 102,938 | 84,776 | 57,182 | 30,273 | 11,825 | 1,510 |  |
Reinsurance | Professional lines | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 131,770 | 107,173 | 85,921 | 53,587 | 29,616 | 10,400 | 779 |  |  |
Reinsurance | Professional lines | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 104,883 | 81,641 | 64,966 | 30,495 | 12,070 | 1,062 |  |  |  |
Reinsurance | Professional lines | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 109,129 | 74,542 | 48,814 | 13,066 | 2,019 |  |  |  |  |
Reinsurance | Professional lines | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 79,270 | 41,524 | 13,505 | 3,134 |  |  |  |  |  |
Reinsurance | Professional lines | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 52,588 | 20,516 | 1,772 |  |  |  |  |  |  |
Reinsurance | Professional lines | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 14,918 | 2,814 |  |  |  |  |  |  |  |
Reinsurance | Professional lines | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 273 |  |  |  |  |  |  |  |  |
Reinsurance | Motor |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 916,565 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 146,464 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 1,172,467 |  |  |  |  |  |  |  |  |
Reinsurance | Motor | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 31,650 | 29,144 | 25,910 | 21,368 | 19,066 | 12,933 | 9,523 | 8,012 | 6,830 | 2,709
Reinsurance | Motor | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 33,083 | 32,015 | 30,977 | 27,766 | 23,554 | 20,387 | 17,066 | 11,951 | 7,075 |
Reinsurance | Motor | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 89,619 | 88,630 | 84,067 | 78,202 | 71,664 | 61,309 | 46,979 | 23,788 |  |
Reinsurance | Motor | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 89,492 | 87,244 | 83,232 | 76,875 | 67,254 | 52,736 | 29,162 |  |  |
Reinsurance | Motor | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 86,832 | 81,388 | 75,865 | 66,119 | 52,639 | 33,807 |  |  |  |
Reinsurance | Motor | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 110,562 | 100,607 | 92,721 | 73,572 | 43,325 |  |  |  |  |
Reinsurance | Motor | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 129,661 | 112,584 | 92,778 | 57,809 |  |  |  |  |  |
Reinsurance | Motor | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 127,970 | 104,342 | 60,829 |  |  |  |  |  |  |
Reinsurance | Motor | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 133,842 | 72,226 |  |  |  |  |  |  |  |
Reinsurance | Motor | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 83,854 |  |  |  |  |  |  |  |  |
Reinsurance | Liability |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 919,946 |  |  |  |  |  |  |  |  |
All outstanding liabilities before 2009, net of reinsurance | 54,315 |  |  |  |  |  |  |  |  |
Liabilities for claims and claim adjustment expenses, net of reinsurance | 1,204,568 |  |  |  |  |  |  |  |  |
Reinsurance | Liability | Accident Year 2009 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 136,539 | 132,996 | 127,009 | 122,704 | 103,662 | 73,229 | 56,623 | 44,473 | 17,102 | $ 1,704
Reinsurance | Liability | Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 128,399 | 119,693 | 108,770 | 97,457 | 83,826 | 62,291 | 46,201 | 17,654 | $ 2,481 |
Reinsurance | Liability | Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 135,625 | 123,387 | 112,328 | 92,466 | 70,102 | 39,981 | 21,273 | $ 5,189 |  |
Reinsurance | Liability | Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 115,571 | 101,115 | 78,190 | 58,735 | 28,388 | 12,798 | $ 3,541 |  |  |
Reinsurance | Liability | Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 102,588 | 88,264 | 69,052 | 52,327 | 22,236 | $ 5,969 |  |  |  |
Reinsurance | Liability | Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 89,436 | 70,143 | 48,415 | 28,663 | $ 7,083 |  |  |  |  |
Reinsurance | Liability | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 80,865 | 54,524 | 27,457 | $ 7,271 |  |  |  |  |  |
Reinsurance | Liability | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 69,526 | 37,688 | $ 11,861 |  |  |  |  |  |  |
Reinsurance | Liability | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | 42,092 | $ 12,424 |  |  |  |  |  |  |  |
Reinsurance | Liability | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance | $ 19,305 |  |  |  |  |  |  |  |  |

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