Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) (USD $) | 3 Months Ended | 9 Months Ended | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010 | ||||||||||
| Gross premiums written | $ 139,938,000 | $ 111,543,000 | $ 1,392,006,000 | $ 1,134,094,000 | |||||||||
| Net premiums written | 103,010,000 | 82,307,000 | 983,580,000 | 818,800,000 | |||||||||
| Net premiums earned | 229,224,000 | 212,355,000 | 751,940,000 | 675,179,000 | |||||||||
| Net claims and claim expenses incurred | 77,830,000 | 77,936,000 | 857,628,000 | 156,473,000 | |||||||||
| Acquisition expenses | 26,057,000 | 26,143,000 | 72,275,000 | 76,158,000 | |||||||||
| Operational expenses | 42,169,000 | 36,970,000 | 126,298,000 | 120,160,000 | |||||||||
| Underwriting income (loss) | 83,168,000 | 71,306,000 | (304,261,000) | 322,388,000 | |||||||||
| Net investment (loss) income | (27,940,000) | 59,570,000 | 65,669,000 | 151,452,000 | |||||||||
| Net foreign exchange losses | (2,650,000) | (529,000) | (6,511,000) | (12,480,000) | |||||||||
| Equity in earnings (losses) of other ventures | 4,794,000 | (6,740,000) | (13,831,000) | (1,424,000) | |||||||||
| Other income (loss) | (2,015,000) | 25,021,000 | 42,963,000 | 15,088,000 | |||||||||
| Net realized and unrealized gains on investments | 16,983,000 | 92,342,000 | 46,748,000 | 210,593,000 | |||||||||
| Net other-than-temporary impairments | (449,000) | (449,000) | (829,000) | ||||||||||
| Corporate expenses | (3,582,000) | (5,590,000) | (9,657,000) | (15,392,000) | |||||||||
| Interest expense | (5,722,000) | (6,164,000) | (17,647,000) | (15,526,000) | |||||||||
| Income from continuing operations before taxes | 62,587,000 | 229,216,000 | (196,976,000) | 653,870,000 | |||||||||
| Income tax benefit | 1,435,000 | 2,399,000 | 3,260,000 | 6,320,000 | |||||||||
| Loss from discontinued operations | (965,000) | 21,234,000 | (12,585,000) | 51,562,000 | |||||||||
| Net (income) loss attributable to noncontrolling interests | (5,044,000) | (37,524,000) | 58,545,000 | (99,989,000) | |||||||||
| Dividends on preference shares | (8,750,000) | (10,575,000) | (26,250,000) | (31,725,000) | |||||||||
| Net (loss) income (attributable) available to RenaissanceRe common shareholders | 49,263,000 | 204,750,000 | (174,006,000) | 580,038,000 | |||||||||
| Net claims and claim expenses incurred - current accident year | 86,430,000 | 114,862,000 | 955,059,000 | 385,907,000 | |||||||||
| Net claims and claim expenses incurred - prior accident years | (8,600,000) | (36,926,000) | (97,431,000) | (229,434,000) | |||||||||
| Net claims and claim expenses incurred - total | 77,830,000 | 77,936,000 | 857,628,000 | 156,473,000 | |||||||||
| Net claims and claim expense ratio - current accident year | 37.70% | 54.10% | 127.00% | 57.20% | |||||||||
| Net claims and claim expense ratio - prior accident years | (3.70%) | (17.40%) | (12.90%) | (34.00%) | |||||||||
| Net claims and claim expense ratio - calendar year | 34.00% | 36.70% | 114.10% | 23.20% | |||||||||
| Underwriting expense ratio | 29.70% | 29.70% | 26.40% | 29.10% | |||||||||
| Combined ratio | 63.70% | 66.40% | 140.50% | 52.30% | |||||||||
Reinsurance [Member] | |||||||||||||
| Gross premiums written | 122,811,000 | 110,577,000 | 1,303,897,000 | 1,105,679,000 | |||||||||
| Net premiums written | 86,745,000 | 86,309,000 | 906,167,000 | 793,967,000 | |||||||||
| Net premiums earned | 208,074,000 | 205,057,000 | 696,964,000 | 646,349,000 | |||||||||
| Net claims and claim expenses incurred | 58,565,000 | 72,480,000 | 797,188,000 | 141,095,000 | |||||||||
| Acquisition expenses | 21,964,000 | 22,464,000 | 62,187,000 | 63,064,000 | |||||||||
| Operational expenses | 32,462,000 | 29,637,000 | 97,726,000 | 93,523,000 | |||||||||
| Underwriting income (loss) | 95,083,000 | 80,476,000 | (260,137,000) | 348,667,000 | |||||||||
| Net claims and claim expenses incurred - current accident year | 72,358,000 | 106,344,000 | 902,118,000 | 361,403,000 | |||||||||
| Net claims and claim expenses incurred - prior accident years | (13,793,000) | (33,864,000) | (104,930,000) | (220,308,000) | |||||||||
| Net claims and claim expenses incurred - total | 58,565,000 | 72,480,000 | 797,188,000 | 141,095,000 | |||||||||
| Net claims and claim expense ratio - current accident year | 34.80% | 51.90% | 129.40% | 55.90% | |||||||||
| Net claims and claim expense ratio - prior accident years | (6.70%) | (16.60%) | (15.00%) | (34.10%) | |||||||||
| Net claims and claim expense ratio - calendar year | 28.10% | 35.30% | 114.40% | 21.80% | |||||||||
| Underwriting expense ratio | 26.20% | 25.50% | 22.90% | 24.30% | |||||||||
| Combined ratio | 54.30% | 60.80% | 137.30% | 46.10% | |||||||||
Insurance [Member] | |||||||||||||
| Gross premiums written | 591,000 | 313,000 | 1,276,000 | ||||||||||
| Net premiums written | 140,000 | (10,143,000) | 467,000 | (27,289,000) | |||||||||
| Net premiums earned | 353,000 | (6,681,000) | 1,272,000 | (8,750,000) | |||||||||
| Net claims and claim expenses incurred | 5,124,000 | (2,231,000) | 7,157,000 | (2,648,000) | |||||||||
| Acquisition expenses | 80,000 | 328,000 | 309,000 | 5,412,000 | |||||||||
| Operational expenses | 147,000 | 1,087,000 | 1,405,000 | 9,304,000 | |||||||||
| Underwriting income (loss) | (4,998,000) | (5,865,000) | (7,599,000) | (20,818,000) | |||||||||
| Net claims and claim expenses incurred - current accident year | (17,000) | 816,000 | (86,000) | 6,302,000 | |||||||||
| Net claims and claim expenses incurred - prior accident years | 5,141,000 | (3,047,000) | 7,243,000 | (8,950,000) | |||||||||
| Net claims and claim expenses incurred - total | 5,124,000 | (2,231,000) | 7,157,000 | (2,648,000) | |||||||||
| Net claims and claim expense ratio - current accident year | (4.80%) | (12.20%) | (6.80%) | (72.00%) | |||||||||
| Net claims and claim expense ratio - prior accident years | 1456.40% | 45.60% | 569.50% | 102.30% | |||||||||
| Net claims and claim expense ratio - calendar year | 1451.60% | 33.40% | 562.70% | 30.30% | |||||||||
| Underwriting expense ratio | 64.30% | (21.20%) | 134.70% | (168.20%) | |||||||||
| Combined ratio | 1515.90% | 12.20% | 697.40% | (137.90%) | |||||||||
Lloyd's [Member] | |||||||||||||
| Gross premiums written | 17,127,000 | 8,762,000 | 87,873,000 | 57,627,000 | |||||||||
| Net premiums written | 16,125,000 | 6,141,000 | 76,946,000 | 52,122,000 | |||||||||
| Net premiums earned | 20,797,000 | 13,979,000 | 53,704,000 | 37,580,000 | |||||||||
| Net claims and claim expenses incurred | 14,141,000 | 7,687,000 | 53,283,000 | 18,026,000 | |||||||||
| Acquisition expenses | 4,013,000 | 3,351,000 | 9,779,000 | 7,682,000 | |||||||||
| Operational expenses | 9,560,000 | 6,246,000 | 27,167,000 | 17,333,000 | |||||||||
| Underwriting income (loss) | (6,917,000) | (3,305,000) | (36,525,000) | (5,461,000) | |||||||||
| Net claims and claim expenses incurred - current accident year | 14,089,000 | 7,702,000 | 53,027,000 | 18,202,000 | |||||||||
| Net claims and claim expenses incurred - prior accident years | 52,000 | (15,000) | 256,000 | (176,000) | |||||||||
| Net claims and claim expenses incurred - total | 14,141,000 | 7,687,000 | 53,283,000 | 18,026,000 | |||||||||
| Net claims and claim expense ratio - current accident year | 67.70% | 55.10% | 98.70% | 48.40% | |||||||||
| Net claims and claim expense ratio - prior accident years | 0.30% | (0.10%) | 0.50% | (0.40%) | |||||||||
| Net claims and claim expense ratio - calendar year | 68.00% | 55.00% | 99.20% | 48.00% | |||||||||
| Underwriting expense ratio | 65.30% | 68.60% | 68.80% | 66.50% | |||||||||
| Combined ratio | 133.30% | 123.60% | 168.00% | 114.50% | |||||||||
Eliminations [Member] | |||||||||||||
| Gross premiums written | (8,387,000) | [1] | (77,000) | [2] | (30,488,000) | [3] | |||||||
All Other Segments [Member] | |||||||||||||
| Net investment (loss) income | (27,940,000) | 59,570,000 | 65,669,000 | 151,452,000 | |||||||||
| Net foreign exchange losses | (2,650,000) | (529,000) | (6,511,000) | (12,480,000) | |||||||||
| Equity in earnings (losses) of other ventures | 4,794,000 | (6,740,000) | (13,831,000) | (1,424,000) | |||||||||
| Other income (loss) | (2,015,000) | 25,021,000 | 42,963,000 | 15,088,000 | |||||||||
| Net realized and unrealized gains on investments | 16,983,000 | 92,342,000 | 46,748,000 | 210,593,000 | |||||||||
| Net other-than-temporary impairments | (449,000) | (449,000) | (829,000) | ||||||||||
| Corporate expenses | (3,582,000) | (5,590,000) | (9,657,000) | (15,392,000) | |||||||||
| Interest expense | (5,722,000) | (6,164,000) | (17,647,000) | (15,526,000) | |||||||||
| Income tax benefit | 1,435,000 | 2,399,000 | 3,260,000 | 6,320,000 | |||||||||
| Loss from discontinued operations | (965,000) | 21,234,000 | (12,585,000) | 51,562,000 | |||||||||
| Net (income) loss attributable to noncontrolling interests | (5,044,000) | (37,524,000) | 58,545,000 | (99,989,000) | |||||||||
| Dividends on preference shares | (8,750,000) | (10,575,000) | (26,250,000) | (31,725,000) | |||||||||
Insurance Segment To Reinsurance Segment [Member] | |||||||||||||
| Gross premiums ceded from segment to segment | 9,800,000 | 10,100,000 | |||||||||||
Reinsurance Segment To Lloyd's Segment [Member] | |||||||||||||
| Gross premiums ceded from segment to segment | 100,000 | 200,000 | |||||||||||
Insurance Segment To Lloyds Segment [Member] | |||||||||||||
| Gross premiums ceded from segment to segment | $ (1,500,000) | $ 20,100,000 | |||||||||||
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