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Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | $ 827,415 | $ 759,128 | $ 1,749,505 | $ 1,621,261
Net premiums written | 555,745 | 519,916 | 1,099,881 | 1,031,591
Net premiums earned | 382,265 | 351,402 | 748,310 | 705,008
Net claims and claim expenses incurred | 142,587 | 167,750 | 335,668 | 294,355
Acquisition expenses | 88,251 | 69,005 | 171,533 | 134,597
Operational expenses | 41,766 | 51,073 | 89,049 | 107,308
Underwriting income (loss) | 109,661 | 63,574 | 152,060 | 168,748
Net investment income | 54,163 | 54,124 | 108,488 | 82,987
Net foreign exchange gains (losses) | 3,109 | (690) | 11,274 | (2,382)
Equity in earnings of other ventures | (5,543) | (6,022) | (4,036) | (7,633)
Other income | 2,392 | 2,654 | 4,057 | 6,733
Net realized and unrealized gains on investments | 58,113 | 69,772 | 101,486 | 131,425
Corporate expenses | (4,636) | (5,752) | (9,922) | (13,977)
Interest expense | (10,091) | (10,536) | (20,617) | (21,074)
Income before taxes | 218,254 | 179,168 | 350,862 | 360,093
Income tax expense | (3,904) | (6,612) | (4,238) | (9,356)
Net income attributable to redeemable noncontrolling interests | (37,612) | (30,635) | (71,939) | (75,226)
Dividends on preference shares | (5,596) | (5,596) | (11,191) | (11,191)
Net income available to RenaissanceRe common shareholders | 171,142 | 136,325 | 263,494 | 264,320
Net claims and claim expenses incurred – current accident year | 187,691 | 197,005 | 351,766 | 325,214
Net claims and claim expenses incurred – prior accident years | (45,104) | (29,255) | (16,098) | (30,859)
Total net incurred | $ 142,587 | $ 167,750 | $ 335,668 | $ 294,355
Net claims and claim expense ratio – current accident year | 49.10% | 56.10% | 47.00% | 46.10%
Net claims and claim expense ratio – prior accident years | (11.80%) | (8.40%) | (2.10%) | (4.30%)
Net claims and claim expense ratio – calendar year | 37.30% | 47.70% | 44.90% | 41.80%
Underwriting expense ratio | 34.00% | 34.20% | 34.80% | 34.30%
Combined ratio | 71.30% | 81.90% | 79.70% | 76.10%
Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | $ 0 | $ 0 | $ 0 | $ 0
Net premiums written | 0 | 0 | 0 | 0
Net premiums earned | 2 | 0 | 0 | 0
Net claims and claim expenses incurred | (227) | 85 | (555) | 3
Acquisition expenses | (1) | 0 | (1) | 0
Operational expenses | 1 | 21 | 12 | 81
Underwriting income (loss) | 229 | (106) | 544 | (84)
Net investment income | 54,163 | 54,124 | 108,488 | 82,987
Net foreign exchange gains (losses) | 3,109 | (690) | 11,274 | (2,382)
Equity in earnings of other ventures | (5,543) | (6,022) | (4,036) | (7,633)
Other income | 2,392 | 2,654 | 4,057 | 6,733
Net realized and unrealized gains on investments | 58,113 | 69,772 | 101,486 | 131,425
Corporate expenses | (4,636) | (5,752) | (9,922) | (13,977)
Interest expense | (10,091) | (10,536) | (20,617) | (21,074)
Income tax expense | (3,904) | (6,612) | (4,238) | (9,356)
Net income attributable to redeemable noncontrolling interests | (37,612) | (30,635) | (71,939) | (75,226)
Dividends on preference shares | (5,596) | (5,596) | (11,191) | (11,191)
Net claims and claim expenses incurred – current accident year | 0 | 0 | 0 | 0
Net claims and claim expenses incurred – prior accident years | (227) | 85 | (555) | 3
Total net incurred | (227) | 85 | (555) | 3
Property |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net claims and claim expenses incurred – prior accident years |  |  | (24,800) | (18,989)
Property | Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | 499,347 | 493,953 | 1,019,876 | 938,912
Net premiums written | 336,464 | 350,593 | 626,335 | 583,452
Net premiums earned | 192,198 | 191,060 | 379,186 | 366,292
Net claims and claim expenses incurred | 33,017 | 80,275 | 71,855 | 102,079
Acquisition expenses | 28,500 | 29,389 | 57,603 | 49,513
Operational expenses | 24,053 | 26,526 | 51,718 | 55,183
Underwriting income (loss) | 106,628 | 54,870 | 198,010 | 159,517
Net claims and claim expenses incurred – current accident year | 56,889 | 93,336 | 96,655 | 121,068
Net claims and claim expenses incurred – prior accident years | (23,872) | (13,061) | (24,800) | (18,989)
Total net incurred | $ 33,017 | $ 80,275 | $ 71,855 | $ 102,079
Net claims and claim expense ratio – current accident year | 29.60% | 48.90% | 25.50% | 33.10%
Net claims and claim expense ratio – prior accident years | (12.40%) | (6.90%) | (6.60%) | (5.20%)
Net claims and claim expense ratio – calendar year | 17.20% | 42.00% | 18.90% | 27.90%
Underwriting expense ratio | 27.30% | 29.30% | 28.90% | 28.60%
Combined ratio | 44.50% | 71.30% | 47.80% | 56.50%
Casualty and Specialty |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net claims and claim expenses incurred – prior accident years |  |  | $ 9,257 | $ (11,873)
Casualty and Specialty | Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | $ 328,068 | $ 265,175 | 729,629 | 682,349
Net premiums written | 219,281 | 169,323 | 473,546 | 448,139
Net premiums earned | 190,065 | 160,342 | 369,124 | 338,716
Net claims and claim expenses incurred | 109,797 | 87,390 | 264,368 | 192,273
Acquisition expenses | 59,752 | 39,616 | 113,931 | 85,084
Operational expenses | 17,712 | 24,526 | 37,319 | 52,044
Underwriting income (loss) | 2,804 | 8,810 | (46,494) | 9,315
Net claims and claim expenses incurred – current accident year | 130,802 | 103,669 | 255,111 | 204,146
Net claims and claim expenses incurred – prior accident years | (21,005) | (16,279) | 9,257 | (11,873)
Total net incurred | $ 109,797 | $ 87,390 | $ 264,368 | $ 192,273
Net claims and claim expense ratio – current accident year | 68.80% | 64.70% | 69.10% | 60.30%
Net claims and claim expense ratio – prior accident years | (11.00%) | (10.20%) | 2.50% | (3.50%)
Net claims and claim expense ratio – calendar year | 57.80% | 54.50% | 71.60% | 56.80%
Underwriting expense ratio | 40.70% | 40.00% | 41.00% | 40.40%
Combined ratio | 98.50% | 94.50% | 112.60% | 97.20%

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- Definition Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387 + Details
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