v2.4.0.6
Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) (USD $)
 3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Gross premiums written $ 664,151,000 $ 610,505,000
Net premiums written 492,575,000 452,575,000
Net premiums earned 278,665,000 305,541,000
Net claims and claim expenses incurred 15,552,000 628,537,000
Acquisition expenses 24,111,000 32,335,000
Operational expenses 42,383,000 41,830,000
Underwriting income (loss) 196,619,000 (397,161,000)
Net investment income 66,971,000 60,281,000
Net foreign exchange losses (1,460,000) 660,000
Equity in earnings (losses) of other ventures 5,470,000 (23,753,000)
Other (loss) income (39,094,000) 50,145,000
Net realized and unrealized gains on investments 46,113,000 (5,214,000)
Net other-than-temporary impairments (134,000) 0
Corporate expenses (4,811,000) (2,064,000)
Interest expense (5,718,000) (6,195,000)
Income (loss) from continuing operations before taxes 263,956,000 (323,301,000)
Income tax benefit (expense) 37,000 52,000
Net (loss) income from discontinued operations (173,000) (1,526,000)
Net loss attributable to noncontrolling interests (53,641,000) 85,492,000
Dividends on preference shares (8,750,000) (8,750,000)
Net income (loss) available (attributable) to RenaissanceRe common shareholders 201,429,000 (248,033,000)
Net claims and claim expenses incurred - current accident year 71,424,000 696,697,000
Net claims and claim expenses incurred - prior accident years (55,872,000) (68,160,000)
Net claims and claim expenses incurred 15,552,000 628,537,000
Net claims and claim expense ratio - current accident year 25.60% 228.00%
Net claims and claim expense ratio - prior accident years (20.00%) (22.30%)
Net claims and claim expense ratio - calendar year 5.60% 205.70%
Underwriting expense ratio 23.80% 24.30%
Combined ratio 29.40% 230.00%
Reinsurance [Member]
    
Gross premiums written 609,762,000 573,682,000
Net premiums written 458,638,000 423,566,000
Net premiums earned 253,818,000 289,429,000
Net claims and claim expenses incurred 8,324,000 595,404,000
Acquisition expenses 19,386,000 29,792,000
Operational expenses 32,044,000 32,363,000
Underwriting income (loss) 194,064,000 (368,130,000)
Net claims and claim expenses incurred - current accident year 55,144,000 667,362,000
Net claims and claim expenses incurred - prior accident years (46,820,000) (71,958,000)
Net claims and claim expenses incurred 8,324,000 595,404,000
Net claims and claim expense ratio - current accident year 21.70% 230.60%
Net claims and claim expense ratio - prior accident years (18.40%) (24.90%)
Net claims and claim expense ratio - calendar year 3.30% 205.70%
Underwriting expense ratio 20.20% 21.50%
Combined ratio 23.50% 227.20%
Lloyd's [Member]
    
Gross premiums written 54,817,000 36,620,000
Net premiums written 33,937,000 28,737,000
Net premiums earned 24,822,000 15,674,000
Net claims and claim expenses incurred 9,001,000 30,523,000
Acquisition expenses 4,668,000 2,461,000
Operational expenses 10,057,000 8,972,000
Underwriting income (loss) 1,096,000 (26,282,000)
Net claims and claim expenses incurred - current accident year 16,280,000 29,326,000
Net claims and claim expenses incurred - prior accident years (7,279,000) 1,197,000
Net claims and claim expenses incurred 9,001,000 30,523,000
Net claims and claim expense ratio - current accident year 65.60% 187.10%
Net claims and claim expense ratio - prior accident years (29.30%) 7.60%
Net claims and claim expense ratio - calendar year 36.30% 194.70%
Underwriting expense ratio 59.30% 73.00%
Combined ratio 95.60% 267.70%
Insurance [Member]
    
Gross premiums written 0 280,000
Net premiums written 0 272,000
Net premiums earned 25,000 438,000
Net claims and claim expenses incurred (1,773,000) 2,610,000
Acquisition expenses 57,000 82,000
Operational expenses 282,000 495,000
Underwriting income (loss) 1,459,000 (2,749,000)
Net claims and claim expenses incurred - current accident year 0 9,000
Net claims and claim expenses incurred - prior accident years (1,773,000) 2,601,000
Net claims and claim expenses incurred (1,773,000) 2,610,000
Net claims and claim expense ratio - current accident year 0.00% 2.10%
Net claims and claim expense ratio - prior accident years (7092.00%) 593.80%
Net claims and claim expense ratio - calendar year (7092.00%) 595.90%
Underwriting expense ratio 1356.00% 131.70%
Combined ratio (5736.00%) 727.60%
Eliminations [Member]
    
Gross premiums written (428,000) [1] (77,000) [2]
All Other Segments [Member]
    
Gross premiums written 0 0
Net premiums written 0 0
Net premiums earned 0 0
Net claims and claim expenses incurred 0 0
Acquisition expenses 0 0
Operational expenses 0 0
Underwriting income (loss) 0 0
Net investment income 66,971,000 60,281,000
Net foreign exchange losses (1,460,000) 660,000
Equity in earnings (losses) of other ventures 5,470,000 (23,753,000)
Other (loss) income (39,094,000) 50,145,000
Net realized and unrealized gains on investments 46,113,000 (5,214,000)
Net other-than-temporary impairments (134,000)  
Corporate expenses (4,811,000) (2,064,000)
Interest expense (5,718,000) (6,195,000)
Income tax benefit (expense) 37,000 52,000
Net (loss) income from discontinued operations (173,000) (1,526,000)
Net loss attributable to noncontrolling interests (53,641,000) 85,492,000
Dividends on preference shares (8,750,000) (8,750,000)
Net claims and claim expenses incurred 0 0
Intersegment Elimination, Reinsurance Segment To Lloyds Segment Member
    
Gross premiums ceded from segment to segment $ 400,000 $ 100,000
[1] Represents $0.4 million of gross premiums ceded from the Reinsurance segment to the Lloyd’s segment.
[2] Represents $0.1 million of gross premiums ceded from the Reinsurance segment to the Lloyd’s segment.