Statutory Requirements (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Statutory Accounting Practices [Line Items]
Assets held in trust	$ 7,000,000	$ 5,700,000
U.S.
Statutory Accounting Practices [Line Items]
Unrestricted net assets	46,630	31,228
New York \| Multi-Beneficiary Reinsurance Trust \| Renaissance Reinsurance Ltd.
Statutory Accounting Practices [Line Items]
Assets held in trust	1,300,000	1,200,000
New York \| Multi-Beneficiary Reinsurance Trust \| Renaissance Reinsurance Ltd. \| Low
Statutory Accounting Practices [Line Items]
Assets held in trust	927,400	1,100,000
New York \| Multi-Beneficiary Reinsurance Trust \| DaVinci Reinsurance Ltd.
Statutory Accounting Practices [Line Items]
Assets held in trust	336,500	385,800
New York \| Multi-Beneficiary Reinsurance Trust \| DaVinci Reinsurance Ltd. \| Low
Statutory Accounting Practices [Line Items]
Assets held in trust	249,400	356,900
New York \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| Renaissance Reinsurance Ltd.
Statutory Accounting Practices [Line Items]
Assets held in trust	51,700	50,300
New York \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| Renaissance Reinsurance Ltd. \| Low
Statutory Accounting Practices [Line Items]
Assets held in trust	40,300	36,800
New York \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| DaVinci Reinsurance Ltd.
Statutory Accounting Practices [Line Items]
Assets held in trust	43,800	63,200
New York \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| DaVinci Reinsurance Ltd. \| Low
Statutory Accounting Practices [Line Items]
Assets held in trust	$ 40,900	$ 26,900
Florida \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| Renaissance Reinsurance Ltd.
Statutory Accounting Practices [Line Items]
Multi-beneficiary reduced collateral reinsurance trust collateral reduction	20.00%
Florida \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| RenaissanceRe Europe
Statutory Accounting Practices [Line Items]
Multi-beneficiary reduced collateral reinsurance trust collateral reduction	20.00%
Florida \| Multi-Beneficiary Reduced Collateral Reinsurance Trust \| DaVinci Reinsurance Ltd.
Statutory Accounting Practices [Line Items]
Multi-beneficiary reduced collateral reinsurance trust collateral reduction	50.00%

Reduction in collateral requirements of multi-beneficiary reinsurance trust to the percentage noted of the net outstanding insurance liabilities.

No definition available.

+ Details

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

- Definition

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(b))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of dividends that can be declared or paid without approval of regulatory agency.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Details

Name:	us-gaap_StatutoryAccountingPracticesByJurisdictionAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatutoryAccountingPracticesByJurisdictionAxis=stpr_NY
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rnr_ReinsuranceTrustFundAxis=rnr_MultiBeneficiaryReinsuranceTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=rnr_RenaissanceReinsuranceLtd.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=rnr_DaVinciReinsuranceLtd.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rnr_ReinsuranceTrustFundAxis=rnr_MultiBeneficiaryReducedCollateralReinsuranceTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatutoryAccountingPracticesByJurisdictionAxis=stpr_FL
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=rnr_RenaissanceReEuropeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: