Noncontrolling Interests (Schedule of Redeemable Noncontrolling Interest) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Activity in redeemable noncontrolling interest
Beginning balance			$ 3,388,319
Net income (loss) attributable to redeemable noncontrolling interest	$ 113,544	$ 118,728	66,694	$ 216,819
Ending balance	3,656,419		3,656,419
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	1,555,714	1,533,085	1,560,693	1,435,581
Redemption of shares from redeemable noncontrolling interest, net of adjustments	2,676	(159)	(153,295)	2,448
Sale of shares to redeemable noncontrolling interests			250,000
Net income (loss) attributable to redeemable noncontrolling interest	84,266	88,374	44,332	173,280
Ending balance	1,642,656	1,621,300	1,642,656	1,621,300
DaVinciRe Holdings Ltd. \| Third-Party Investors And RenaissanceRe
Activity in redeemable noncontrolling interest
Sale of shares to redeemable noncontrolling interests	0	0	190,926	9,991
Medici
Activity in redeemable noncontrolling interest
Beginning balance	737,702	677,283	717,999	632,112
Redemption of shares from redeemable noncontrolling interest, net of adjustments	(46)	(44,474)	(7,745)	(49,238)
Sale of shares to redeemable noncontrolling interests	130,675	36,158	171,520	90,771
Net income (loss) attributable to redeemable noncontrolling interest	11,989	13,151	(1,454)	8,473
Ending balance	880,320	682,118	880,320	682,118
Vermeer Reinsurance Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	1,116,154	1,021,478	1,109,627	1,003,615
Sale of shares to redeemable noncontrolling interests	0	45,000	0	45,000
Net income (loss) attributable to redeemable noncontrolling interest	17,289	17,203	23,816	35,066
Ending balance	$ 1,133,443	$ 1,083,681	$ 1,133,443	$ 1,083,681

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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

- Definition

Decrease in noncontrolling interest (for example, but not limited to, redeeming or purchasing the interests of noncontrolling shareholders, issuance of shares (interests) by the non-wholly owned subsidiary to the parent entity for other than cash, and a buyback of shares (interest) by the non-wholly owned subsidiary from the noncontrolling interests).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=123454820&loc=SL4569655-111683

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=123454820&loc=SL4616395-111683

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_MinorityInterestDecreaseFromRedemptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of Net Income (Loss) attributable to redeemable noncontrolling interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.19)
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

+ Details

Name:	us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase in noncontrolling interest from subsidiary issuance of equity interests to noncontrolling interest holders.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=123454820&loc=SL4569655-111683

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

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

- Definition

As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph (16)(c)
-URI http://asc.fasb.org/extlink&oid=122040564&loc=SL6540498-122764

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph 15
-URI http://asc.fasb.org/extlink&oid=122040564&loc=SL6540498-122764

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph (12)(c)
-URI http://asc.fasb.org/extlink&oid=122040564&loc=SL6540498-122764

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph 14
-URI http://asc.fasb.org/extlink&oid=122040564&loc=SL6540498-122764

+ Details

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

- Details

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

- Details

Name:	srt_CounterpartyNameAxis=rnr_ThirdPartyInvestorsAndRenaissanceReMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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