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Reserve for Claims and Claim Expenses (Schedule of Incurred and Paid Claims Development) (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | 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
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | $ 15,089,621 |  |  |  |  |  |  |  |  |
IBNR and ACR | 4,142,784 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 8,946,583 |  |  |  |  |  |  |  |  |
Outstanding liabilities from accident year 2009 and prior, net of reinsurance | 270,317 |  |  |  |  |  |  |  |  |
Claims and claim expenses, net of reinsurance, from the Company's former Bermuda-based insurance operations | 229 |  |  |  |  |  |  |  |  |
Adjustment for unallocated claim expenses | 51,876 |  |  |  |  |  |  |  |  |
Unamortized fair value adjustments recorded in connection with acquisitions | (69,219) |  |  |  |  |  |  |  |  |
Liability for claims and claim expenses, net of reinsurance | 6,593,052 |  |  |  |  |  |  |  |  |
Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 6,990,689 |  |  |  |  |  |  |  |  |
IBNR and ACR | 1,446,950 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 4,732,479 |  |  |  |  |  |  |  |  |
Outstanding liabilities from accident year 2009 and prior, net of reinsurance | 4,283 |  |  |  |  |  |  |  |  |
Adjustment for unallocated claim expenses | 19,339 |  |  |  |  |  |  |  |  |
Unamortized fair value adjustments recorded in connection with acquisitions | (10,606) |  |  |  |  |  |  |  |  |
Liability for claims and claim expenses, net of reinsurance | 2,288,762 |  |  |  |  |  |  |  |  |
Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 8,098,932 |  |  |  |  |  |  |  |  |
IBNR and ACR | 2,695,834 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 4,214,104 |  |  |  |  |  |  |  |  |
Outstanding liabilities from accident year 2009 and prior, net of reinsurance | 266,034 |  |  |  |  |  |  |  |  |
Adjustment for unallocated claim expenses | 32,537 |  |  |  |  |  |  |  |  |
Unamortized fair value adjustments recorded in connection with acquisitions | (58,613) |  |  |  |  |  |  |  |  |
Liability for claims and claim expenses, net of reinsurance | 4,304,061 |  |  |  |  |  |  |  |  |
Accident Year 2010 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,052,931 | $ 1,015,540 | $ 1,043,565 | $ 1,045,490 | $ 1,037,725 | $ 1,045,727 | $ 1,033,341 | $ 1,048,747 | $ 1,105,041 | $ 1,131,892
IBNR and ACR | 60,342 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 928,552 | 912,776 | 892,480 | 859,745 | 746,454 | 670,935 | 603,060 | 518,162 | 334,347 | 146,890
Accident Year 2010 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 731,179 | 681,435 | 708,343 | 706,258 | 696,844 | 691,473 | 657,719 | 636,962 | 681,287 | 720,159
IBNR and ACR | 50,422 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 623,231 | 612,013 | 595,131 | 581,160 | 481,489 | 450,624 | 401,977 | 345,574 | 230,552 | 104,859
Accident Year 2010 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 321,752 | 334,105 | 335,222 | 339,232 | 340,881 | 354,254 | 375,622 | 411,785 | 423,754 | 411,733
IBNR and ACR | 9,920 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 305,321 | 300,763 | 297,349 | 278,585 | 264,965 | 220,311 | 201,083 | 172,588 | 103,795 | $ 42,031
Accident Year 2011 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,664,869 | 1,678,015 | 1,683,614 | 1,698,378 | 1,738,452 | 1,768,793 | 1,827,258 | 1,926,506 | 1,989,024 |
IBNR and ACR | 55,191 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 1,565,359 | 1,550,195 | 1,530,030 | 1,493,174 | 1,449,060 | 1,330,492 | 1,143,829 | 728,464 | 311,906 |
Accident Year 2011 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,302,141 | 1,321,137 | 1,333,982 | 1,338,187 | 1,369,567 | 1,393,110 | 1,422,659 | 1,491,770 | 1,559,069 |
IBNR and ACR | 24,335 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 1,264,414 | 1,257,516 | 1,252,204 | 1,230,503 | 1,207,136 | 1,121,374 | 965,668 | 590,346 | 262,987 |
Accident Year 2011 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 362,728 | 356,878 | 349,632 | 360,191 | 368,885 | 375,683 | 404,599 | 434,736 | 429,955 |
IBNR and ACR | 30,856 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 300,945 | 292,679 | 277,826 | 262,671 | 241,924 | 209,118 | 178,161 | 138,118 | $ 48,919 |
Accident Year 2012 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 907,212 | 901,049 | 894,168 | 891,981 | 927,438 | 958,139 | 1,021,668 | 1,138,018 |  |
IBNR and ACR | 48,297 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 783,106 | 752,614 | 721,942 | 647,618 | 596,634 | 522,264 | 416,808 | 267,764 |  |
Accident Year 2012 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 331,865 | 336,719 | 344,535 | 356,310 | 375,098 | 395,203 | 429,425 | 559,946 |  |
IBNR and ACR | 12,351 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 313,976 | 308,822 | 305,627 | 291,027 | 280,195 | 253,699 | 205,567 | 165,850 |  |
Accident Year 2012 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 575,347 | 564,330 | 549,633 | 535,671 | 552,340 | 562,936 | 592,243 | 578,072 |  |
IBNR and ACR | 35,946 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 469,130 | 443,792 | 416,315 | 356,591 | 316,439 | 268,565 | 211,241 | $ 101,914 |  |
Accident Year 2013 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 699,767 | 718,563 | 737,158 | 761,033 | 810,934 | 861,093 | 912,545 |  |  |
IBNR and ACR | 43,792 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 615,463 | 587,978 | 554,686 | 496,380 | 434,508 | 340,652 | 131,829 |  |  |
Accident Year 2013 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 222,939 | 224,748 | 228,622 | 240,945 | 265,570 | 287,694 | 317,258 |  |  |
IBNR and ACR | 1,092 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 219,231 | 216,176 | 213,351 | 206,376 | 191,181 | 155,459 | 80,083 |  |  |
Accident Year 2013 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 476,828 | 493,815 | 508,536 | 520,088 | 545,364 | 573,399 | 595,287 |  |  |
IBNR and ACR | 42,700 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 396,232 | 371,802 | 341,335 | 290,004 | 243,327 | 185,193 | $ 51,746 |  |  |
Accident Year 2014 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 953,904 | 948,264 | 966,802 | 990,050 | 997,906 | 1,024,813 |  |  |  |
IBNR and ACR | 114,985 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 741,844 | 691,774 | 630,417 | 554,398 | 432,761 | 230,826 |  |  |  |
Accident Year 2014 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 265,229 | 264,754 | 265,820 | 270,618 | 283,608 | 306,731 |  |  |  |
IBNR and ACR | 4,554 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 247,663 | 241,139 | 234,144 | 222,509 | 184,140 | 106,618 |  |  |  |
Accident Year 2014 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 688,675 | 683,510 | 700,982 | 719,432 | 714,298 | 718,082 |  |  |  |
IBNR and ACR | 110,431 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 494,181 | 450,635 | 396,273 | 331,889 | 248,621 | $ 124,208 |  |  |  |
Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,133,632 | 1,145,983 | 1,175,927 | 1,156,856 | 1,171,023 |  |  |  |  |
IBNR and ACR | 131,005 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 879,950 | 781,622 | 662,001 | 495,119 | 262,085 |  |  |  |  |
Accident Year 2015 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 301,733 | 307,088 | 317,865 | 334,572 | 368,766 |  |  |  |  |
IBNR and ACR | 11,672 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 279,165 | 268,545 | 249,182 | 215,134 | 126,831 |  |  |  |  |
Accident Year 2015 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 831,899 | 838,895 | 858,062 | 822,284 | 802,257 |  |  |  |  |
IBNR and ACR | 119,333 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 600,785 | 513,077 | 412,819 | 279,985 | $ 135,254 |  |  |  |  |
Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,426,575 | 1,432,001 | 1,458,767 | 1,401,451 |  |  |  |  |  |
IBNR and ACR | 251,952 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 971,424 | 826,502 | 623,440 | 286,317 |  |  |  |  |  |
Accident Year 2016 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 432,269 | 443,135 | 458,525 | 445,532 |  |  |  |  |  |
IBNR and ACR | 53,990 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 350,646 | 324,296 | 258,355 | 119,908 |  |  |  |  |  |
Accident Year 2016 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 994,306 | 988,866 | 1,000,242 | 955,919 |  |  |  |  |  |
IBNR and ACR | 197,962 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 620,778 | 502,206 | 365,085 | $ 166,409 |  |  |  |  |  |
Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 2,632,396 | 2,724,795 | 2,940,713 |  |  |  |  |  |  |
IBNR and ACR | 731,975 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 1,371,477 | 1,067,481 | 745,098 |  |  |  |  |  |  |
Accident Year 2017 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,348,260 | 1,446,566 | 1,640,129 |  |  |  |  |  |  |
IBNR and ACR | 295,210 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 824,443 | 660,491 | 534,097 |  |  |  |  |  |  |
Accident Year 2017 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,284,136 | 1,278,229 | 1,300,584 |  |  |  |  |  |  |
IBNR and ACR | 436,765 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 547,034 | 406,990 | $ 211,001 |  |  |  |  |  |  |
Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 2,338,291 | 2,198,980 |  |  |  |  |  |  |  |
IBNR and ACR | 940,346 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 804,566 | 587,619 |  |  |  |  |  |  |  |
Accident Year 2018 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,054,884 | 945,829 |  |  |  |  |  |  |  |
IBNR and ACR | 273,477 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 450,125 | 432,201 |  |  |  |  |  |  |  |
Accident Year 2018 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,283,407 | 1,253,151 |  |  |  |  |  |  |  |
IBNR and ACR | 666,869 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 354,441 | $ 155,418 |  |  |  |  |  |  |  |
Accident Year 2019 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 2,280,044 |  |  |  |  |  |  |  |  |
IBNR and ACR | 1,764,899 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 284,842 |  |  |  |  |  |  |  |  |
Accident Year 2019 | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,000,190 |  |  |  |  |  |  |  |  |
IBNR and ACR | 719,847 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 159,585 |  |  |  |  |  |  |  |  |
Accident Year 2019 | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and claim expenses, net of reinsurance | 1,279,854 |  |  |  |  |  |  |  |  |
IBNR and ACR | 1,045,052 |  |  |  |  |  |  |  |  |
Cumulative paid claims and claim expenses, net of reinsurance | 125,257 |  |  |  |  |  |  |  |  |
RenaissanceRe UK |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for claims and claim expenses, net of reinsurance | 196,811 |  |  |  |  |  |  |  |  |
RenaissanceRe UK | Property |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for claims and claim expenses, net of reinsurance | 17,536 |  |  |  |  |  |  |  |  |
RenaissanceRe UK | Casualty and Specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for claims and claim expenses, net of reinsurance | $ 179,275 |  |  |  |  |  |  |  |  |

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- Definition Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Unamortized Fair Value Adjustments Associated With Acquisition + References No definition available. + Details
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- Definition Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4E -URI http://asc.fasb.org/extlink&oid=116884468&loc=SL65671321-158438 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4D -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=116884468&loc=SL65671317-158438 + Details
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- Definition Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4C -URI http://asc.fasb.org/extlink&oid=116884468&loc=SL65671315-158438 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4B -URI http://asc.fasb.org/extlink&oid=116884468&loc=SL65671311-158438 + Details
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