Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Gross premiums written	$ 547,755	$ 625,677	$ 977,343	$ 1,159,652	$ 407,766	$ 640,269	$ 827,415	$ 922,090	$ 3,310,427	$ 2,797,540	$ 2,374,576
Net premiums written (Note 6)	411,094	453,255	604,509	663,044	288,223	483,221	555,745	544,136	2,131,902	1,871,325	1,535,312
Increase in unearned premiums	163,519	78,594	(175,124)	(222,762)	133,250	64,571	(173,480)	(178,091)	(155,773)	(153,750)	(131,882)
Net premiums earned (Note 6)	574,613	531,849	429,385	440,282	421,473	547,792	382,265	366,045	1,976,129	1,717,575	1,403,430
Net investment income (Note 4)	53,338	80,696	71,356	56,476	73,464	40,257	54,163	54,325	261,866	222,209	181,726
Net foreign exchange (losses) gains	(932)	(4,566)	(10,687)	3,757	(490)	(156)	3,109	8,165	(12,428)	10,628	(13,788)
Equity in earnings of other ventures (Note 4)	4,143	7,648	5,826	857	2,200	1,794	5,543	(1,507)	18,474	8,030	963
Other income	5,489	497	1,225	(1,242)	2,362	2,996	2,392	1,665	5,969	9,415	14,178
Net realized and unrealized (losses) gains on investments (Note 4)	(88,654)	13,630	(17,901)	(82,144)	(7,716)	42,052	58,113	43,373	(175,069)	135,822	141,328
Total revenues	547,997	629,754	479,204	417,986	491,293	634,735	505,585	472,066	2,074,941	2,103,679	1,727,837
Expenses
Net claims and claim expenses incurred (Notes 6 and 7)	477,638	410,510	60,167	171,703	304,064	1,221,696	142,587	193,081	1,120,018	1,861,428	530,831
Acquisition expenses	120,465	109,761	105,052	97,711	98,598	76,761	88,251	83,282	432,989	346,892	289,323
Operational expenses	58,859	40,593	37,543	41,272	29,192	42,537	41,766	47,283	178,267	160,778	197,749
Corporate expenses	12,108	6,841	8,301	6,733	4,237	4,413	4,636	5,286	33,983	18,572	37,402
Interest expense (Note 8)	11,765	11,769	11,768	11,767	11,777	11,799	10,091	10,526	47,069	44,193	42,144
Total expenses	680,835	579,474	222,831	329,186	447,868	1,357,206	287,331	339,458	1,812,326	2,431,863	1,097,449
Income (loss) before taxes	(132,838)	50,280	256,373	88,800	43,425	(722,471)	218,254	132,608	262,615	(328,184)	630,388
Income tax benefit (expense) (Note 14)	8,852	(1,451)	(4,506)	3,407	(41,226)	18,977	(3,904)	(334)	6,302	(26,487)	(340)
Net income (loss)	(123,986)	48,829	251,867	92,207	2,199	(703,494)	214,350	132,274	268,917	(354,671)	630,048
Net (income) loss attributable to redeemable noncontrolling interests (Note 9)	49,269	(6,440)	(54,483)	(29,899)	(56)	204,277	(37,612)	(34,327)	(41,553)	132,282	(127,086)
Net income (loss) attributable to RenaissanceRe	(74,717)	42,389	197,384	62,308	2,143	(499,217)	176,738	97,947	227,364	(222,389)	502,962
Dividends on preference shares	(9,189)	(9,708)	(5,596)	(5,595)	(5,595)	(5,595)	(5,596)	(5,595)	(30,088)	(22,381)	(22,381)
Net income (loss) available (attributable) to RenaissanceRe common shareholders	$ (83,906)	$ 32,681	$ 191,788	$ 56,713	$ (3,452)	$ (504,812)	$ 171,142	$ 92,352	$ 197,276	$ (244,770)	$ 480,581
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – basic (Note 12) (in usd per share)	$ (2.10)	$ 0.82	$ 4.78	$ 1.42	$ (0.09)	$ (12.75)	$ 4.25	$ 2.26	$ 4.91	$ (6.15)	$ 11.50
Net income (loss) available (attributable) to RenaissanceRe common shareholders per common share – diluted (Note 12) (in usd per share)	$ (2.10)	$ 0.82	$ 4.78	$ 1.42	$ (0.09)	$ (12.75)	$ 4.24	$ 2.25	$ 4.91	$ (6.15)	$ 11.43