Consolidated Statements of Operations - 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
Gross premiums written	$ 905,479	$ 861,068	$ 1,476,908	$ 1,564,295	$ 547,755	$ 625,677	$ 977,343	$ 1,159,652	$ 4,807,750	$ 3,310,427	$ 2,797,540
Net premiums written (Note 7)	725,367	704,130	1,022,965	929,031	411,094	453,255	604,509	663,044	3,381,493	2,131,902	1,871,325
Increase in unearned premiums	244,758	202,618	(111,463)	(379,003)	163,519	78,594	(175,124)	(222,762)	(43,090)	(155,773)	(153,750)
Net premiums earned (Note 7)	970,125	906,748	911,502	550,028	574,613	531,849	429,385	440,282	3,338,403	1,976,129	1,717,575
Net investment income (Note 5)	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 (losses) gains	(1,126)	(8,275)	9,309	(2,846)	(932)	(4,566)	(10,687)	3,757	(2,938)	(12,428)	10,628
Equity in earnings of other ventures (Note 5)	5,874	5,877	6,812	4,661	4,143	7,648	5,826	857	23,224	18,474	8,030
Other income	(160)	1,016	922	3,171	5,489	497	1,225	(1,242)	4,949	5,969	9,415
Net realized and unrealized gains (losses) on investments (Note 5)	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
Net claims and claim expenses incurred (Notes 7 and 8)	762,093	654,520	453,373	227,035	477,638	410,510	60,167	171,703	2,097,021	1,120,018	1,861,428
Acquisition expenses	208,618	202,181	227,482	123,951	120,465	109,761	105,052	97,711	762,232	432,989	346,892
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
Interest expense (Note 9)	15,496	15,580	15,534	11,754	11,765	11,769	11,768	11,767	58,364	47,069	44,193
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
Income (loss) before taxes	36,885	111,608	458,330	360,659	(132,838)	50,280	256,373	88,800	967,482	262,615	(328,184)
Income tax (expense) benefit (Note 15)	3,455	(3,664)	(9,475)	(7,531)	8,852	(1,451)	(4,506)	3,407	(17,215)	6,302	(26,487)
Net income (loss)	40,340	107,944	448,855	353,128	(123,986)	48,829	251,867	92,207	950,267	268,917	(354,671)
Net (income) loss attributable to redeemable noncontrolling interests (Note 10)	2,622	(62,057)	(71,812)	(70,222)	49,269	(6,440)	(54,483)	(29,899)	(201,469)	(41,553)	132,282
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)
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – basic (Note 12) (in usd per share)	$ 0.77	$ 0.83	$ 8.36	$ 6.43	$ (2.10)	$ 0.82	$ 4.78	$ 1.42	$ 16.32	$ 4.91	$ (6.15)
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – diluted (Note 12) (in usd per share)	$ 0.77	$ 0.83	$ 8.35	$ 6.43	$ (2.10)	$ 0.82	$ 4.78	$ 1.42	$ 16.29	$ 4.91	$ (6.15)