Assets (Liabilities), Fair Value Disclosure, Recurring

No definition available.

Name:	rnr_AssetsLiabilitiesFairValueDisclosureRecurring
Namespace Prefix:	rnr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the weighted average life in years of debt securities.

+ References

No definition available.

+ Details

Name:	rnr_DebtSecuritiesWeightedAverageLife
Namespace Prefix:	rnr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimated Liquidation Period of Limited Partnership Assets, Maximum

+ References

No definition available.

+ Details

Name:	rnr_EstimatedLiquidationPeriodOfLimitedPartnershipAssetsMaximum
Namespace Prefix:	rnr_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimated Liquidation Period of Limited Partnership Assets, Minimum

+ References

No definition available.

+ Details

Name:	rnr_EstimatedLiquidationPeriodOfLimitedPartnershipAssetsMinimum
Namespace Prefix:	rnr_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimated percentage return for the period on fair value at beginning of period.

+ References

No definition available.

+ Details

Name:	rnr_FairValueInputsEstimatedPerformance
Namespace Prefix:	rnr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents senior secured bank loan funds in a closed end fund, which the Company has no right to redeem.

+ References

No definition available.

+ Details

Name:	rnr_InvestmentInClosedEndFund
Namespace Prefix:	rnr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the fair value of investments redeemable in part, on a monthly basis, or in whole over a three month period.

+ References

No definition available.

+ Details

Name:	rnr_InvestmentsRedeemableInPartMonthlyInTotalOverThreeMonths
Namespace Prefix:	rnr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents 'side pocket' investments which are not redeemable at the option of the shareholder.

+ References

No definition available.

+ Details

Name:	rnr_NonredeemableSidePocketInvestments
Namespace Prefix:	rnr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Total Other Assets And liabilities Measured on Recurring Basis

+ References

No definition available.

+ Details

Name:	rnr_TotalOtherAssetsAndLiabilitiesMeasuredOnRecurringBasis
Namespace Prefix:	rnr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the weighted average effective yield percentage of debt securities.

+ References

No definition available.

+ Details

Name:	rnr_WeightedAverageEffectiveYield
Namespace Prefix:	rnr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_AssetsFairValueDisclosureRecurring
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest rate stated in the contractual debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DebtInstrumentMaturityDateDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of investments, not including unrealized gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, held at each balance sheet date and included in earnings for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

+ Details

Name:	us-gaap_UnrealizedGainLossOnInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended			3 Months Ended														3 Months Ended				3 Months Ended				3 Months Ended				3 Months Ended											3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
Fair Value Measurements (Narrative) (Details) (USD $)	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Other Investments [Member] Net investment income (loss) [Member]	Mar. 31, 2012 Other Investments [Member] Net investment income (loss) [Member]	Mar. 31, 2013 Other Assets and Liabilities [Member] Other income (loss) [Member]	Mar. 31, 2012 Other Assets and Liabilities [Member] Other income (loss) [Member]	Mar. 31, 2010 5.75% Senior Notes Due March 15, 2020 [Member] RenRe North America Holdings Inc. [Member]	Mar. 31, 2013 5.75% Senior Notes Due March 15, 2020 [Member] RenRe North America Holdings Inc. [Member]	Dec. 31, 2012 5.75% Senior Notes Due March 15, 2020 [Member] RenRe North America Holdings Inc. [Member]	Mar. 17, 2010 5.75% Senior Notes Due March 15, 2020 [Member] RenRe North America Holdings Inc. [Member]	Mar. 31, 2013 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2012 Significant Other Observable Inputs (Level 2) [Member]	Mar. 31, 2013 Significant Other Observable Inputs (Level 2) [Member] Cash Settled Restricted Stock Unit [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Hedge funds [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Hedge funds [Member] Minimum [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Hedge funds [Member] Maximum [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Hedge funds [Member] Weighted Average or Actual [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Senior secured bank loan funds [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Senior secured bank loan funds [Member] Minimum [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Senior secured bank loan funds [Member] Maximum [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Senior secured bank loan funds [Member] Weighted Average or Actual [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Private Equity Funds [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Private Equity Funds [Member] Minimum [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Private Equity Funds [Member] Maximum [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Private Equity Funds [Member] Weighted Average or Actual [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Other [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Other [Member] Weighted Average or Actual [Member] Net Asset Valuation Technique [Member]	Mar. 31, 2013 U.S. treasuries [Member]	Dec. 31, 2012 U.S. treasuries [Member]	Mar. 31, 2013 Agencies [Member]	Dec. 31, 2012 Agencies [Member]	Mar. 31, 2013 Non-U.S. government (Sovereign Debt) [Member]	Dec. 31, 2012 Non-U.S. government (Sovereign Debt) [Member]	Mar. 31, 2013 Non-U.S. government-backed corporate [Member]	Dec. 31, 2012 Non-U.S. government-backed corporate [Member]	Mar. 31, 2013 Corporate [Member]	Dec. 31, 2012 Corporate [Member]	Mar. 31, 2013 Agency mortgage-backed [Member]	Dec. 31, 2012 Agency mortgage-backed [Member]	Mar. 31, 2013 Non-agency prime residential mortgage-backed [Member]	Dec. 31, 2012 Non-agency prime residential mortgage-backed [Member]	Mar. 31, 2013 AltA non-agency mortgage-backed [Member]	Dec. 31, 2012 AltA non-agency mortgage-backed [Member]	Mar. 31, 2013 Commercial mortgage-backed [Member]	Dec. 31, 2012 Commercial mortgage-backed [Member]	Mar. 31, 2013 Asset-backed [Member]	Dec. 31, 2012 Asset-backed [Member]	Mar. 31, 2013 Senior secured bank loan funds [Member]	Mar. 31, 2013 Hedge funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average effective yield																															0.50%	0.40%	0.70%	0.70%	1.50%	1.90%	0.70%	0.70%	2.50%	2.60%	2.00%	1.30%	3.40%	3.60%	4.80%	5.20%	1.90%	1.70%	0.80%	1.80%
Weighted average life																																									3 years 9 months 18 days	3 years 3 months 18 days	4 years 4 months 24 days	4 years 6 months	4 years 8 months 12 days	4 years 8 months 12 days	3 years 7 months 6 days	3 years 8 months 12 days	3 years 3 months 18 days	3 years 6 months
Investments redeemable in part, on a monthly basis, or in whole over a three month period																																																			$ 175,600,000
Assets and (liabilities) at fair value	22,958,000		29,085,000									1,231,000	3,270,000	(2,000,000)	21,328,000	25,940,000
Assets, Fair Value Disclosure, Recurring															451,601,000		5,219,000				28,537,000				345,666,000				22,784,000
Fair Value Inputs, Estimated Performance																		0.00%	0.00%	0.00%		0.80%	2.10%	1.30%		(12.00%)	120.00%	4.90%		0.90%
5.75% Senior notes issued											250,000,000
Senior notes interest rate									5.75%
Debt instrument maturity date								March 15, 2020
Senior Notes, Fair value									284,200,000	281,200,000
Net unrealized gains (losses) recognized in earnings	13,102,000	36,061,000		15,100,000	35,300,000	0	(2,100,000)
Minimum estimated liquidation period	7
Maximim estimated liquidation period	10
Investment in closed end fund																																																			28,500,000
Hedge fund side pocket investments																																																				5,200,000
Assets (Liabilities), Fair Value Disclosure, Recurring															$ 21,328,000														$ 22,784,000