Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Gross premiums written	$ 323,091	$ 430,224	$ 759,128	$ 862,133	$ 336,093	$ 369,642	$ 661,997	$ 643,578	$ 2,374,576	$ 2,011,310	$ 1,550,572
Net premiums written	219,499	284,222	519,916	511,675	236,651	266,820	508,677	404,035	1,535,312	1,416,183	1,068,236
Net premiums earned	351,901	346,521	351,402	353,606	361,575	362,388	379,828	296,760	1,403,430	1,400,551	1,062,416
Net claims and claim expenses incurred	123,901	112,575	167,750	126,605	102,013	100,028	169,344	76,853	530,831	448,238	197,947
Acquisition expenses	74,146	80,580	69,005	65,592	55,399	78,126	61,666	43,401	289,323	238,592	144,476
Operational expenses	49,948	40,493	51,073	56,235	64,300	54,518	54,673	45,621	197,749	219,112	190,639
Underwriting income (loss)									385,527	494,609	529,354
Net investment income	47,316	51,423	54,124	28,863	45,918	28,338	38,604	39,707	181,726	152,567	124,316
Net foreign exchange (losses) gains	(5,420)	(5,986)	(690)	(1,692)	1,203	616	(1,740)	(3,130)	(13,788)	(3,051)	6,260
Equity in earnings (losses) of other ventures	4,960	(11,630)	6,022	1,611	3,296	5,730	6,160	5,295	963	20,481	26,075
Other income (loss)	5,177	2,268	2,654	4,079	8,200	2,306	1,427	1,539	14,178	13,472	(423)
Net realized and unrealized gains (losses) on investments	(49,967)	59,870	69,772	61,653	(42,817)	(41,138)	(26,712)	41,749	141,328	(68,918)	41,433
Corporate expenses	(11,888)	(11,537)	(5,752)	(8,225)	(10,791)	(7,322)	(12,868)	(45,533)	(37,402)	(76,514)	(22,749)
Interest expense	(10,534)	(10,536)	(10,536)	(10,538)	(10,550)	(10,542)	(9,862)	(5,316)	(42,144)	(36,270)	(17,402)
Income before taxes	83,550	186,745	179,168	180,925	134,322	107,704	89,154	165,196	630,388	496,376	686,864
Income tax (expense) benefit	7,700	1,316	(6,612)	(2,744)	(8,453)	4,573	1,842	47,904	(340)	45,866	(608)
Net income attributable to redeemable noncontrolling interests	(16,219)	(35,641)	(30,635)	(44,591)	(28,068)	(31,153)	(12,167)	(39,662)	(127,086)	(111,050)	(153,538)
Dividends on preference shares	(5,595)	(5,595)	(5,596)	(5,595)	(5,595)	(5,595)	(5,596)	(5,595)	(22,381)	(22,381)	(22,381)
Net income available to RenaissanceRe common shareholders	$ 69,436	$ 146,825	$ 136,325	$ 127,995	$ 92,206	$ 75,529	$ 73,233	$ 167,843	480,581	408,811	510,337
Net claims and claim expenses incurred - current accident year									694,957	610,685	341,745
Net claims and claim expenses incurred – prior accident years									(164,126)	(162,447)	(143,798)
Total net incurred									$ 530,831	$ 448,238	$ 197,947
Net claims and claim expense ratio - current accident year									49.50%	43.60%	32.20%
Net claims and claim expense ratio - prior accident years									(11.70%)	(11.60%)	(13.60%)
Net claims and claim expense ratio - calendar year									37.80%	32.00%	18.60%
Underwriting expense ratio									34.70%	32.70%	31.60%
Combined ratio									72.50%	64.70%	50.20%
Other
Segment Reporting Information [Line Items]
Gross premiums written									$ 0	$ (90)	$ 309
Net premiums written									143	(48)	344
Net premiums earned									142	(48)	368
Net claims and claim expenses incurred									(1,110)	(870)	(6,137)
Acquisition expenses									0	248	(6,548)
Operational expenses									123	266	303
Underwriting income (loss)									1,129	308	12,750
Net investment income									181,726	152,567	124,316
Net foreign exchange (losses) gains									(13,788)	(3,051)	6,260
Equity in earnings (losses) of other ventures									963	20,481	26,075
Other income (loss)									14,178	13,472	(423)
Net realized and unrealized gains (losses) on investments									141,328	(68,918)	41,433
Corporate expenses									(37,402)	(76,514)	(22,749)
Interest expense									(42,144)	(36,270)	(17,402)
Income tax (expense) benefit									(340)	45,866	(608)
Net income attributable to redeemable noncontrolling interests									(127,086)	(111,050)	(153,538)
Dividends on preference shares									(22,381)	(22,381)	(22,381)
Net claims and claim expenses incurred - current accident year									0	0	0
Net claims and claim expenses incurred – prior accident years									(1,110)	(870)	(6,137)
Total net incurred									(1,110)	(870)	(6,137)
Property
Segment Reporting Information [Line Items]
Gross premiums written									1,111,263	1,072,159	1,074,890
Net claims and claim expenses incurred – prior accident years									(104,876)	(93,786)	(87,258)
Property | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written									1,111,263	1,072,159	1,074,890
Net premiums written									725,321	726,145	662,552
Net premiums earned									720,951	805,985	698,416
Net claims and claim expenses incurred									151,545	128,290	16,643
Acquisition expenses									97,594	94,249	66,262
Operational expenses									108,642	118,666	117,943
Underwriting income (loss)									363,170	464,780	497,568
Net claims and claim expenses incurred - current accident year									256,421	222,076	103,901
Net claims and claim expenses incurred – prior accident years									(104,876)	(93,786)	(87,258)
Total net incurred									$ 151,545	$ 128,290	$ 16,643
Net claims and claim expense ratio - current accident year									35.60%	27.60%	14.90%
Net claims and claim expense ratio - prior accident years									(14.60%)	(11.70%)	(12.50%)
Net claims and claim expense ratio - calendar year									21.00%	15.90%	2.40%
Underwriting expense ratio									28.60%	26.40%	26.40%
Combined ratio									49.60%	42.30%	28.80%
Casualty and Specialty
Segment Reporting Information [Line Items]
Gross premiums written									$ 1,263,313	$ 939,241	$ 475,373
Net claims and claim expenses incurred – prior accident years									(58,140)	(67,791)	(50,403)
Casualty and Specialty | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written									1,263,313	939,241	475,373
Net premiums written									809,848	690,086	405,340
Net premiums earned									682,337	594,614	363,632
Net claims and claim expenses incurred									380,396	320,818	187,441
Acquisition expenses									191,729	144,095	84,762
Operational expenses									88,984	100,180	72,393
Underwriting income (loss)									21,228	29,521	19,036
Net claims and claim expenses incurred - current accident year									438,536	388,609	237,844
Net claims and claim expenses incurred – prior accident years									(58,140)	(67,791)	(50,403)
Total net incurred									$ 380,396	$ 320,818	$ 187,441
Net claims and claim expense ratio - current accident year									64.30%	65.40%	65.40%
Net claims and claim expense ratio - prior accident years									(8.60%)	(11.40%)	(13.90%)
Net claims and claim expense ratio - calendar year									55.70%	54.00%	51.50%
Underwriting expense ratio									41.20%	41.00%	43.30%
Combined ratio									96.90%	95.00%	94.80%