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Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | $ 640,269 | $ 430,224 | $ 2,389,774 | $ 2,051,485
Net premiums written | 483,221 | 284,222 | 1,583,102 | 1,315,813
Net premiums earned | 547,792 | 346,521 | 1,296,102 | 1,051,529
Net claims and claim expenses incurred | 1,221,696 | 112,575 | 1,557,364 | 406,930
Acquisition expenses | 76,761 | 80,580 | 248,294 | 215,177
Operational expenses | 42,537 | 40,493 | 131,586 | 147,801
Underwriting (loss) income | (793,202) | 112,873 | (641,142) | 281,621
Net investment income | 40,257 | 51,423 | 148,745 | 134,410
Net foreign exchange (losses) gains | (156) | (5,986) | 11,118 | (8,368)
Equity in earnings (losses) of other ventures | 1,794 | (11,630) | 5,830 | (3,997)
Other income | 2,996 | 2,268 | 7,053 | 9,001
Net realized and unrealized gains on investments | 42,052 | 59,870 | 143,538 | 191,295
Corporate expenses | (4,413) | (11,537) | (14,335) | (25,514)
Interest expense | (11,799) | (10,536) | (32,416) | (31,610)
(Loss) income before taxes | (722,471) | 186,745 | (371,609) | 546,838
Income tax benefit (expense) | 18,977 | 1,316 | 14,739 | (8,040)
Net loss (income) attributable to redeemable noncontrolling interests | 204,277 | (35,641) | 132,338 | (110,867)
Dividends on preference shares | (5,595) | (5,595) | (16,786) | (16,786)
Net (loss) income (attributable) available to RenaissanceRe common shareholders | (504,812) | 146,825 | (241,318) | 411,145
Net claims and claim expenses incurred – current accident year | 1,209,261 | 158,360 | 1,561,027 | 483,574
Net claims and claim expenses incurred – prior accident years | 12,435 | (45,785) | (3,663) | (76,644)
Total net incurred | $ 1,221,696 | $ 112,575 | $ 1,557,364 | $ 406,930
Net claims and claim expense ratio – current accident year | 220.80% | 45.70% | 120.40% | 46.00%
Net claims and claim expense ratio – prior accident years | 2.20% | (13.20%) | (0.20%) | (7.30%)
Net claims and claim expense ratio – calendar year | 223.00% | 32.50% | 120.20% | 38.70%
Underwriting expense ratio | 21.80% | 34.90% | 29.30% | 34.50%
Combined ratio | 244.80% | 67.40% | 149.50% | 73.20%
Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | $ (7) | $ 0 | $ (7) | $ 0
Net premiums written | (7) | 0 | (7) | 0
Net premiums earned | (7) | 0 | (7) | 0
Net claims and claim expenses incurred | (155) | (808) | (710) | (805)
Acquisition expenses | (1) | 0 | (2) | 0
Operational expenses | 25 | 18 | 37 | 99
Underwriting (loss) income | 124 | 790 | 668 | 706
Net investment income | 40,257 | 51,423 | 148,745 | 134,410
Net foreign exchange (losses) gains | (156) | (5,986) | 11,118 | (8,368)
Equity in earnings (losses) of other ventures | 1,794 | (11,630) | 5,830 | (3,997)
Other income | 2,996 | 2,268 | 7,053 | 9,001
Net realized and unrealized gains on investments | 42,052 | 59,870 | 143,538 | 191,295
Corporate expenses | (4,413) | (11,537) | (14,335) | (25,514)
Interest expense | (11,799) | (10,536) | (32,416) | (31,610)
Income tax benefit (expense) | 18,977 | 1,316 | 14,739 | (8,040)
Net loss (income) attributable to redeemable noncontrolling interests | 204,277 | (35,641) | 132,338 | (110,867)
Dividends on preference shares | (5,595) | (5,595) | (16,786) | (16,786)
Net claims and claim expenses incurred – current accident year | 0 | 0 | 0 | 0
Net claims and claim expenses incurred – prior accident years | (155) | (808) | (710) | (805)
Total net incurred | (155) | (808) | (710) | (805)
Property |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net claims and claim expenses incurred – prior accident years |  |  | (16,968) | (37,512)
Property | Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | 325,395 | 119,904 | 1,345,271 | 1,058,816
Net premiums written | 269,393 | 90,909 | 895,728 | 674,361
Net premiums earned | 336,838 | 172,661 | 716,024 | 538,953
Net claims and claim expenses incurred | 1,044,418 | 23,539 | 1,116,273 | 125,618
Acquisition expenses | 17,514 | 21,663 | 75,117 | 71,176
Operational expenses | 25,123 | 24,258 | 76,841 | 79,441
Underwriting (loss) income | (750,217) | 103,201 | (552,207) | 262,718
Net claims and claim expenses incurred – current accident year | 1,036,586 | 42,062 | 1,133,241 | 163,130
Net claims and claim expenses incurred – prior accident years | 7,832 | (18,523) | (16,968) | (37,512)
Total net incurred | $ 1,044,418 | $ 23,539 | $ 1,116,273 | $ 125,618
Net claims and claim expense ratio – current accident year | 307.70% | 24.40% | 158.30% | 30.30%
Net claims and claim expense ratio – prior accident years | 2.40% | (10.80%) | (2.40%) | (7.00%)
Net claims and claim expense ratio – calendar year | 310.10% | 13.60% | 155.90% | 23.30%
Underwriting expense ratio | 12.60% | 26.60% | 21.20% | 28.00%
Combined ratio | 322.70% | 40.20% | 177.10% | 51.30%
Casualty and Specialty |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net claims and claim expenses incurred – prior accident years |  |  | $ 14,015 | $ (38,327)
Casualty and Specialty | Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Gross premiums written | $ 314,881 | $ 310,320 | 1,044,510 | 992,669
Net premiums written | 213,835 | 193,313 | 687,381 | 641,452
Net premiums earned | 210,961 | 173,860 | 580,085 | 512,576
Net claims and claim expenses incurred | 177,433 | 89,844 | 441,801 | 282,117
Acquisition expenses | 59,248 | 58,917 | 173,179 | 144,001
Operational expenses | 17,389 | 16,217 | 54,708 | 68,261
Underwriting (loss) income | (43,109) | 8,882 | (89,603) | 18,197
Net claims and claim expenses incurred – current accident year | 172,675 | 116,298 | 427,786 | 320,444
Net claims and claim expenses incurred – prior accident years | 4,758 | (26,454) | 14,015 | (38,327)
Total net incurred | $ 177,433 | $ 89,844 | $ 441,801 | $ 282,117
Net claims and claim expense ratio – current accident year | 81.90% | 66.90% | 73.70% | 62.50%
Net claims and claim expense ratio – prior accident years | 2.20% | (15.20%) | 2.50% | (7.50%)
Net claims and claim expense ratio – calendar year | 84.10% | 51.70% | 76.20% | 55.00%
Underwriting expense ratio | 36.30% | 43.20% | 39.20% | 41.40%
Combined ratio | 120.40% | 94.90% | 115.40% | 96.40%

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