Noncontrolling Interests (Schedule of Redeemable Noncontrolling Interest) (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
Jun. 01, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Activity in redeemable noncontrolling interest
Beginning balance				$ 3,071,308
Net income attributable to redeemable noncontrolling interest		$ 118,728	$ 71,812	216,819	$ 142,034
Ending balance		3,387,099		3,387,099
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		1,533,085	1,097,245	1,435,581	1,034,946
Redemption of shares from redeemable noncontrolling interest, net of adjustments		(159)	(698)	2,448	(932)
Sale of shares to redeemable noncontrolling interests	$ 349,200	0	274,699	9,991	274,699
Net income attributable to redeemable noncontrolling interest		88,374	59,855	173,280	122,388
Ending balance		1,621,300	1,431,101	1,621,300	1,431,101
RenaissanceRe Medici Fund Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		677,283	406,958	632,112	416,765
Redemption of shares from redeemable noncontrolling interest, net of adjustments		(44,474)	(21,556)	(49,238)	(37,440)
Sale of shares to redeemable noncontrolling interests		36,158	128,809	90,771	132,405
Net income attributable to redeemable noncontrolling interest		13,151	1,704	8,473	4,185
Ending balance		682,118	515,915	682,118	515,915
Vermeer Reinsurance Ltd.
Activity in redeemable noncontrolling interest
Beginning balance		1,021,478	605,197	1,003,615	599,989
Sale of shares to redeemable noncontrolling interests		45,000	150,000	45,000	150,000
Net income attributable to redeemable noncontrolling interest		17,203	10,253	35,066	15,461
Ending balance		$ 1,083,681	$ 765,450	$ 1,083,681	$ 765,450

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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