Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Gross premiums written	$ 430,224	$ 369,642	$ 2,051,485	$ 1,675,217
Net premiums written	284,222	266,820	1,315,813	1,179,532
Net premiums earned	346,521	362,388	1,051,529	1,038,976
Net claims and claim expenses incurred	112,575	100,028	406,930	346,225
Acquisition expenses	80,580	78,126	215,177	183,193
Operational expenses	40,493	54,518	147,801	154,812
Underwriting income (loss)	112,873	129,716	281,621	354,746
Net investment income	51,423	28,338	134,410	106,649
Net foreign exchange (losses) gains	(5,986)	616	(8,368)	(4,254)
Equity in (losses) earnings of other ventures	(11,630)	5,730	(3,997)	17,185
Other income	2,268	2,306	9,001	5,272
Net realized and unrealized gains (losses) on investments	59,870	(41,138)	191,295	(26,101)
Corporate expenses	(11,537)	(7,322)	(25,514)	(65,723)
Interest expense	(10,536)	(10,542)	(31,610)	(25,720)
Income before taxes	186,745	107,704	546,838	362,054
Income tax benefit (expense)	1,316	4,573	(8,040)	54,319
Net income attributable to redeemable noncontrolling interests	(35,641)	(31,153)	(110,867)	(82,982)
Dividends on preference shares	(5,595)	(5,595)	(16,786)	(16,786)
Net income available to RenaissanceRe common shareholders	146,825	75,529	411,145	316,605
Net claims and claim expenses incurred – current accident year	158,360	170,378	483,574	471,796
Net claims and claim expenses incurred – prior accident years	(45,785)	(70,350)	(76,644)	(125,571)
Net claims and claim expenses incurred – total	$ 112,575	$ 100,028	$ 406,930	$ 346,225
Net claims and claim expense ratio – current accident year	45.70%	47.00%	46.00%	45.40%
Net claims and claim expense ratio – prior accident years	(13.20%)	(19.40%)	(7.30%)	(12.10%)
Net claims and claim expense ratio – calendar year	32.50%	27.60%	38.70%	33.30%
Underwriting expense ratio	34.90%	36.60%	34.50%	32.60%
Combined ratio	67.40%	64.20%	73.20%	65.90%
Catastrophe Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 67,394	$ 81,692	$ 825,271	$ 856,305
Net premiums written	37,526	55,182	481,956	548,312
Net premiums earned	121,062	159,641	399,663	466,113
Net claims and claim expenses incurred	927	22,319	64,878	85,289
Acquisition expenses	7,603	14,048	33,410	41,016
Operational expenses	16,355	23,513	55,308	65,966
Underwriting income (loss)	96,177	99,761	246,067	273,842
Net claims and claim expenses incurred – current accident year	18,267	36,244	102,471	127,702
Net claims and claim expenses incurred – prior accident years	(17,340)	(13,925)	(37,593)	(42,413)
Net claims and claim expenses incurred – total	$ 927	$ 22,319	$ 64,878	$ 85,289
Net claims and claim expense ratio – current accident year	15.10%	22.70%	25.60%	27.40%
Net claims and claim expense ratio – prior accident years	(14.30%)	(8.70%)	(9.40%)	(9.10%)
Net claims and claim expense ratio – calendar year	0.80%	14.00%	16.20%	18.30%
Underwriting expense ratio	19.80%	23.50%	22.20%	22.90%
Combined ratio	20.60%	37.50%	38.40%	41.20%
Specialty Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 270,876	$ 214,372	$ 840,598	$ 498,676
Net premiums written	177,331	155,987	569,842	399,769
Net premiums earned	150,766	146,213	443,252	396,673
Net claims and claim expenses incurred	82,113	41,005	241,666	166,655
Acquisition expenses	52,019	50,432	127,871	99,372
Operational expenses	15,360	17,542	57,092	49,579
Underwriting income (loss)	1,274	37,234	16,623	81,067
Net claims and claim expenses incurred – current accident year	102,025	96,737	275,520	250,316
Net claims and claim expenses incurred – prior accident years	(19,912)	(55,732)	(33,854)	(83,661)
Net claims and claim expenses incurred – total	$ 82,113	$ 41,005	$ 241,666	$ 166,655
Net claims and claim expense ratio – current accident year	67.70%	66.20%	62.20%	63.10%
Net claims and claim expense ratio – prior accident years	(13.20%)	(38.20%)	(7.70%)	(21.10%)
Net claims and claim expense ratio – calendar year	54.50%	28.00%	54.50%	42.00%
Underwriting expense ratio	44.70%	46.50%	41.70%	37.60%
Combined ratio	99.20%	74.50%	96.20%	79.60%
Lloyd's | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 91,954	$ 73,578	$ 385,616	$ 320,326
Net premiums written	69,365	55,651	264,015	231,540
Net premiums earned	74,693	56,534	208,614	176,279
Net claims and claim expenses incurred	29,337	36,425	100,185	93,951
Acquisition expenses	20,958	13,654	53,896	42,557
Operational expenses	8,760	13,427	35,302	39,086
Underwriting income (loss)	15,638	(6,972)	19,231	685
Net claims and claim expenses incurred – current accident year	38,068	37,397	105,583	93,778
Net claims and claim expenses incurred – prior accident years	(8,731)	(972)	(5,398)	173
Net claims and claim expenses incurred – total	$ 29,337	$ 36,425	$ 100,185	$ 93,951
Net claims and claim expense ratio – current accident year	51.00%	66.10%	50.60%	53.20%
Net claims and claim expense ratio – prior accident years	(11.70%)	(1.70%)	(2.60%)	0.10%
Net claims and claim expense ratio – calendar year	39.30%	64.40%	48.00%	53.30%
Underwriting expense ratio	39.80%	47.90%	42.80%	46.30%
Combined ratio	79.10%	112.30%	90.80%	99.60%
Other | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 0	$ 0	$ 0	$ (90)
Net premiums written	0	0	0	(89)
Net premiums earned	0	0	0	(89)
Net claims and claim expenses incurred	198	279	201	330
Acquisition expenses	0	(8)	0	248
Operational expenses	18	36	99	181
Underwriting income (loss)	(216)	(307)	(300)	(848)
Net investment income	51,423	28,338	134,410	106,649
Net foreign exchange (losses) gains	(5,986)	616	(8,368)	(4,254)
Equity in (losses) earnings of other ventures	(11,630)	5,730	(3,997)	17,185
Other income	2,268	2,306	9,001	5,272
Net realized and unrealized gains (losses) on investments	59,870	(41,138)	191,295	(26,101)
Corporate expenses	(11,537)	(7,322)	(25,514)	(65,723)
Interest expense	(10,536)	(10,542)	(31,610)	(25,720)
Income tax benefit (expense)	1,316	4,573	(8,040)	54,319
Net income attributable to redeemable noncontrolling interests	(35,641)	(31,153)	(110,867)	(82,982)
Dividends on preference shares	(5,595)	(5,595)	(16,786)	(16,786)
Net claims and claim expenses incurred – current accident year	0	0	0	0
Net claims and claim expenses incurred – prior accident years	198	279	201	330
Net claims and claim expenses incurred – total	$ 198	$ 279	$ 201	330
Intersegment Eliminations
Segment Reporting Information [Line Items]
Gross premiums written				$ 100