Schedule II. Condensed Financial Information Of Registrant (Statements of Operations) (Details) - 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
Net investment income	$ 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	(932)	(4,566)	(10,687)	3,757	(490)	(156)	3,109	8,165	(12,428)	10,628	(13,788)
Other loss	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	(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
Interest expense	11,765	11,769	11,768	11,767	11,777	11,799	10,091	10,526	47,069	44,193	42,144
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
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
Loss before equity in net income (loss) of subsidiaries									262,615	(328,184)	630,388
Equity in net income (loss) of subsidiaries									0	0	0
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
Parent Company
Revenues
Net investment income									24,791	23,109	24,178
Net foreign exchange losses									(3)	(1)	(2)
Other loss									0	0	(772)
Net realized and unrealized (losses) gains on investments									633	(1,357)	4,151
Total revenues									25,421	21,751	27,555
Expenses
Interest expense									5,683	1,572	562
Operational expenses									7,679	11,314	13,716
Corporate expenses									25,190	18,546	26,848
Total expenses									38,552	31,432	41,126
Loss before equity in net income (loss) of subsidiaries									(13,131)	(9,681)	(13,571)
Equity in net income (loss) of subsidiaries									240,495	(212,708)	516,533
Net income (loss) attributable to RenaissanceRe									227,364	(222,389)	502,962
Dividends on preference shares									(30,088)	(22,381)	(22,381)
Net income (loss) available (attributable) to RenaissanceRe common shareholders									$ 197,276	$ (244,770)	$ 480,581