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Fair Value Measurements (Narrative) (Details) (USD $)
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3 Months Ended | 3 Months Ended | 0 Months Ended | 0 Months Ended | 3 Months Ended | |||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2012
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Mar. 31, 2011
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Dec. 31, 2011
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Mar. 31, 2012
Other Investments [Member]
Investment Income, Net [Member]
|
Mar. 31, 2011
Other Investments [Member]
Investment Income, Net [Member]
|
Mar. 31, 2012
Other Assets and Liabilities [Member]
Other (Loss) Income [Member]
|
Mar. 31, 2011
Other Assets and Liabilities [Member]
Other (Loss) Income [Member]
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Jan. 03, 2003
5.875% Senior Notes Due February 15, 2013 [Member]
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Mar. 31, 2012
5.875% Senior Notes Due February 15, 2013 [Member]
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Dec. 31, 2011
5.875% Senior Notes Due February 15, 2013 [Member]
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Mar. 17, 2010
5.75% Senior Notes Due March 15, 2020 [Member]
RenRe North America Holdings Inc. [Member]
|
Mar. 31, 2012
5.75% Senior Notes Due March 15, 2020 [Member]
RenRe North America Holdings Inc. [Member]
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Dec. 31, 2011
5.75% Senior Notes Due March 15, 2020 [Member]
RenRe North America Holdings Inc. [Member]
|
Mar. 31, 2012
U.S. treasuries [Member]
|
Dec. 31, 2011
U.S. treasuries [Member]
|
Mar. 31, 2012
Agencies [Member]
|
Dec. 31, 2011
Agencies [Member]
|
Mar. 31, 2012
Non-U.S. government (Sovereign Debt) [Member]
|
Dec. 31, 2011
Non-U.S. government (Sovereign Debt) [Member]
|
Mar. 31, 2012
FDIC guaranteed corporate [Member]
|
Dec. 31, 2011
FDIC guaranteed corporate [Member]
|
Mar. 31, 2012
Non-U.S. government-backed corporate [Member]
|
Dec. 31, 2011
Non-U.S. government-backed corporate [Member]
|
Mar. 31, 2012
Corporate [Member]
|
Dec. 31, 2011
Corporate [Member]
|
Mar. 31, 2012
Agency mortgage-backed [Member]
years
|
Dec. 31, 2011
Agency mortgage-backed [Member]
years
|
Mar. 31, 2012
Non-agency prime residential mortgage-backed [Member]
years
|
Dec. 31, 2011
Non-agency prime residential mortgage-backed [Member]
years
|
Mar. 31, 2012
AltA non-agency mortgage-backed [Member]
years
|
Dec. 31, 2011
AltA non-agency mortgage-backed [Member]
years
|
Mar. 31, 2012
Commercial mortgage-backed [Member]
years
|
Dec. 31, 2011
Commercial mortgage-backed [Member]
years
|
Mar. 31, 2012
Asset-backed [Member]
years
|
Dec. 31, 2011
Asset-backed [Member]
years
|
Mar. 31, 2012
Private equity partnerships [Member]
|
Mar. 31, 2012
Senior secured bank loan funds [Member]
|
Mar. 31, 2012
Non-U.S. fixed income funds [Member]
|
Mar. 31, 2012
Hedge funds [Member]
|
Mar. 31, 2012
Other [Member]
|
Dec. 31, 2011
Other [Member]
|
Mar. 31, 2012
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
|
Dec. 31, 2011
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
|
Mar. 31, 2012
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Other [Member]
|
Dec. 31, 2011
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Other [Member]
|
Mar. 31, 2012
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Cash Settled Restricted Stock Unit [Member]
|
|
| Weighted average effective yield | 0.60% | 0.60% | 0.70% | 0.50% | 2.90% | 2.30% | 0.20% | 0.30% | 1.30% | 1.40% | 3.70% | 4.20% | 1.40% | 1.50% | 6.40% | 8.00% | 6.70% | 9.10% | 2.70% | 3.20% | 0.50% | 0.90% | ||||||||||||||||||||||||
| Weighted average life | 2.6 | 2.6 | 3.5 | 3.3 | 3.9 | 3.8 | 3.9 | 4.2 | 1.2 | 1.8 | ||||||||||||||||||||||||||||||||||||
| Investment in closed end fund | $ 21,000,000 | |||||||||||||||||||||||||||||||||||||||||||||
| Senior Notes, Carrying value | 100,000,000 | |||||||||||||||||||||||||||||||||||||||||||||
| Senior notes interest rate | 5.875% | 5.75% | ||||||||||||||||||||||||||||||||||||||||||||
| Debt instrument maturity date | February 15, 2013 | March 15, 2020 | ||||||||||||||||||||||||||||||||||||||||||||
| Senior Notes, Fair value | 103,500,000 | 103,400,000 | 262,000,000 | 263,000,000 | ||||||||||||||||||||||||||||||||||||||||||
| Debt instrument, Face amount | 250,000,000 | |||||||||||||||||||||||||||||||||||||||||||||
| Net unrealized gains (losses) recognized in earnings | 36,061,000 | 28,067,000 | 35,300,000 | 28,100,000 | (2,100,000) | (42,700,000) | ||||||||||||||||||||||||||||||||||||||||
| Investments redeemable in part, on a monthly basis, or in whole over a three month period | 245,100,000 | |||||||||||||||||||||||||||||||||||||||||||||
| Assets and (liabilities) at fair value | 53,504,000 | 16,071,000 | 13,936,000 | 10,644,000 | (1,068,000) | (6,162,000) | (1,481,000) | (6,869,000) | (1,500,000) | |||||||||||||||||||||||||||||||||||||
| Estimated liquidation period of limited partnership assets, Minimum | 7 years | |||||||||||||||||||||||||||||||||||||||||||||
| Estimated liquidation period of limited partnership assets, Maximum | 10 years | |||||||||||||||||||||||||||||||||||||||||||||
| Other investments measured using net asset valuations | 709,615,000 | 389,451,000 | 266,141,000 | 31,713,000 | 22,310,000 | |||||||||||||||||||||||||||||||||||||||||
| Hedge fund side pocket investments | $ 6,700,000 | |||||||||||||||||||||||||||||||||||||||||||||