Noncontrolling Interests (Schedule of Redeemable Noncontrolling Interest) (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
Jun. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Activity in redeemable noncontrolling interest
Beginning balance				$ 3,071,308
Net income attributable to redeemable noncontrolling interest		$ 19,301	$ 62,057	236,120	$ 204,091
Ending balance		3,387,317		3,387,317
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		1,621,300	1,431,101	1,435,581	1,034,946
Redemption of shares from redeemable noncontrolling interest, net of adjustments		(1)	1,018	2,447	86
Sale of shares to redeemable noncontrolling interests	$ 349,200	0	0	9,991	274,699
Net income attributable to redeemable noncontrolling interest		(26,616)	30,558	146,664	152,946
Ending balance		1,594,683	1,462,677	1,594,683	1,462,677
RenaissanceRe Medici Fund Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		682,118	515,915	632,112	416,765
Redemption of shares from redeemable noncontrolling interest, net of adjustments		(31,174)	(7,008)	(80,412)	(44,448)
Sale of shares to redeemable noncontrolling interests		12,092	10,500	102,863	142,905
Net income attributable to redeemable noncontrolling interest		33,963	15,211	42,436	19,396
Ending balance		696,999	534,618	696,999	534,618
Vermeer Reinsurance Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		1,083,681	765,450	1,003,615	599,989
Sale of shares to redeemable noncontrolling interests		0	0	45,000	150,000
Net income attributable to redeemable noncontrolling interest		11,954	16,288	47,020	31,749
Ending balance		$ 1,095,635	$ 781,738	$ 1,095,635	$ 781,738

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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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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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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