Schedule II. Condensed Financial Information Of Registrant (Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Net investment income	$ 112,695	$ 113,844	$ 115,832	$ 81,462	$ 53,338	$ 80,696	$ 71,356	$ 56,476	$ 423,833	$ 261,866	$ 222,209
Net foreign exchange gains (losses)	(1,126)	(8,275)	9,309	(2,846)	(932)	(4,566)	(10,687)	3,757	(2,938)	(12,428)	10,628
Net realized and unrealized gains (losses) on investments	17,897	31,938	194,003	170,645	(88,654)	13,630	(17,901)	(82,144)	414,483	(175,069)	135,822
Total revenues	1,105,305	1,051,148	1,238,380	807,121	547,997	629,754	479,204	417,986	4,201,954	2,074,941	2,103,679
Expenses
Interest expense	15,496	15,580	15,534	11,754	11,765	11,769	11,768	11,767	58,364	47,069	44,193
Operational expenses	64,571	53,415	59,814	44,933	58,859	40,593	37,543	41,272	222,733	178,267	160,778
Corporate expenses	17,642	13,844	23,847	38,789	12,108	6,841	8,301	6,733	94,122	33,983	18,572
Total expenses	1,068,420	939,540	780,050	446,462	680,835	579,474	222,831	329,186	3,234,472	1,812,326	2,431,863
Loss before equity in net income (loss) of subsidiaries									967,482	262,615	(328,184)
Equity in net income (loss) of subsidiaries									0	0	0
Net income (loss) attributable to RenaissanceRe	42,962	45,887	377,043	282,906	(74,717)	42,389	197,384	62,308	748,798	227,364	(222,389)
Dividends on preference shares	(9,189)	(9,189)	(9,189)	(9,189)	(9,189)	(9,708)	(5,596)	(5,595)	(36,756)	(30,088)	(22,381)
Net income (loss) available (attributable) to RenaissanceRe common shareholders	$ 33,773	$ 36,698	$ 367,854	$ 273,717	$ (83,906)	$ 32,681	$ 191,788	$ 56,713	712,042	197,276	(244,770)
Parent Company
Revenues
Net investment income									39,629	24,791	23,109
Net foreign exchange gains (losses)									7,342	(3)	(1)
Net realized and unrealized gains (losses) on investments									12,393	633	(1,357)
Total revenues									59,364	25,421	21,751
Expenses
Interest expense									18,086	5,683	1,572
Operational expenses									7,506	7,679	11,314
Corporate expenses									58,393	25,190	18,546
Total expenses									83,985	38,552	31,432
Loss before equity in net income (loss) of subsidiaries									(24,621)	(13,131)	(9,681)
Equity in net income (loss) of subsidiaries									773,419	240,495	(212,708)
Net income (loss) attributable to RenaissanceRe									748,798	227,364	(222,389)
Dividends on preference shares									(36,756)	(30,088)	(22,381)
Net income (loss) available (attributable) to RenaissanceRe common shareholders									$ 712,042	$ 197,276	$ (244,770)