Noncontrolling Interests (Schedule of Redeemable Noncontrolling Interest) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Activity in redeemable noncontrolling interest
Beginning balance	$ 1,296,506
Sale of shares to redeemable noncontrolling interest	1
Comprehensive income:
Net income (loss) attributable to redeemable noncontrolling interest	41,553	$ (132,282)	$ 127,086
Ending balance	2,051,700	1,296,506
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	1,011,659	994,458
Redemption of shares from redeemable noncontrolling interest	(4,351)	(80,058)
Sale of shares to redeemable noncontrolling interest	0	232,119
Comprehensive income:
Net income (loss) attributable to redeemable noncontrolling interest	27,638	(134,860)	118,748
Ending balance	1,034,946	1,011,659	994,458
RenaissanceRe Medici Fund Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	284,847	181,136
Redemption of shares from redeemable noncontrolling interest	(90,490)	(48,049)
Sale of shares to redeemable noncontrolling interest	208,482	149,182
Comprehensive income:
Net income (loss) attributable to redeemable noncontrolling interest	13,926	2,578	8,338
Ending balance	416,765	284,847	181,136
Vermeer Reinsurance Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	0	0
Sale of shares to redeemable noncontrolling interest	600,000	0
Comprehensive income:
Net income (loss) attributable to redeemable noncontrolling interest	(11)	0	0
Ending balance	$ 599,989	$ 0	$ 0

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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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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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