Noncontrolling Interests (Schedule of Redeemable Noncontrolling Interest Activity) (Details) - USD ($) $ in Thousands		12 Months Ended
Jun. 01, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Activity in redeemable noncontrolling interest
Beginning balance		$ 3,071,308
Comprehensive income:
Net income attributable to redeemable noncontrolling interests		230,653	$ 201,469	$ 41,553
Ending balance		3,388,319	3,071,308
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		1,435,581	1,034,946
Redemption of shares from redeemable noncontrolling interests, net of adjustments		1,450	(1,148)
Sale of shares to redeemable noncontrolling interests	$ 349,200	9,991	274,699
Comprehensive income:
Net income attributable to redeemable noncontrolling interests		113,671	127,084	27,638
Ending balance		1,560,693	1,435,581	1,034,946
RenaissanceRe Medici Fund Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		632,112	416,765
Redemption of shares from redeemable noncontrolling interests, net of adjustments		(107,386)	(47,401)
Sale of shares to redeemable noncontrolling interests		137,303	236,989
Comprehensive income:
Net income attributable to redeemable noncontrolling interests		55,970	25,759	13,926
Ending balance		717,999	632,112	416,765
Vermeer Reinsurance Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		1,003,615	599,989
Sale of shares to redeemable noncontrolling interests		45,000	355,000
Comprehensive income:
Net income attributable to redeemable noncontrolling interests		61,012	48,626	(11)
Ending balance		$ 1,109,627	$ 1,003,615	$ 599,989

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

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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).

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- Definition

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

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

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- 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.

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