Segment Reporting (Schedule Of Significant Components Of The Company's Revenues And Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Gross premiums written	$ 759,128	$ 661,997	$ 1,621,261	$ 1,305,575
Net premiums written	519,916	508,677	1,031,591	912,712
Net premiums earned	351,402	379,828	705,008	676,588
Net claims and claim expenses incurred	167,750	169,344	294,355	246,197
Acquisition expenses	69,005	61,666	134,597	105,067
Operational expenses	51,073	54,673	107,308	100,294
Underwriting income (loss)	63,574	94,145	168,748	225,030
Net investment income	54,124	38,604	82,987	78,311
Net foreign exchange losses	(690)	(1,740)	(2,382)	(4,870)
Equity in earnings of other ventures	6,022	6,160	7,633	11,455
Other income	2,654	1,427	6,733	2,966
Net realized and unrealized gains (losses) on investments	69,772	(26,712)	131,425	15,037
Corporate expenses	(5,752)	(12,868)	(13,977)	(58,401)
Interest expense	(10,536)	(9,862)	(21,074)	(15,178)
Income before taxes	179,168	89,154	360,093	254,350
Income tax (expense) benefit	(6,612)	1,842	(9,356)	49,746
Net income attributable to redeemable noncontrolling interests	(30,635)	(12,167)	(75,226)	(51,829)
Dividends on preference shares	(5,596)	(5,596)	(11,191)	(11,191)
Net income available to RenaissanceRe common shareholders	136,325	73,233	264,320	241,076
Net claims and claim expenses incurred – current accident year	197,005	202,420	325,214	301,418
Net claims and claim expenses incurred – prior accident years	(29,255)	(33,076)	(30,859)	(55,221)
Net claims and claim expenses incurred – total	$ 167,750	$ 169,344	$ 294,355	$ 246,197
Net claims and claim expense ratio – current accident year	56.10%	53.30%	46.10%	44.50%
Net claims and claim expense ratio – prior accident years	(8.40%)	(8.70%)	(4.30%)	(8.10%)
Net claims and claim expense ratio – calendar year	47.70%	44.60%	41.80%	36.40%
Underwriting expense ratio	34.20%	30.60%	34.30%	30.30%
Combined ratio	81.90%	75.20%	76.10%	66.70%
Catastrophe Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 397,454	$ 385,366	$ 757,877	$ 774,613
Net premiums written	255,645	270,490	444,430	493,130
Net premiums earned	141,616	162,705	278,601	306,472
Net claims and claim expenses incurred	56,131	55,376	63,951	62,970
Acquisition expenses	16,227	19,314	25,807	26,968
Operational expenses	18,685	22,090	38,953	42,453
Underwriting income (loss)	50,573	65,925	149,890	174,081
Net claims and claim expenses incurred – current accident year	70,321	67,334	84,204	91,458
Net claims and claim expenses incurred – prior accident years	(14,190)	(11,958)	(20,253)	(28,488)
Net claims and claim expenses incurred – total	$ 56,131	$ 55,376	$ 63,951	$ 62,970
Net claims and claim expense ratio – current accident year	49.70%	41.40%	30.20%	29.80%
Net claims and claim expense ratio – prior accident years	(10.10%)	(7.40%)	(7.20%)	(9.30%)
Net claims and claim expense ratio – calendar year	39.60%	34.00%	23.00%	20.50%
Underwriting expense ratio	24.70%	25.50%	23.20%	22.70%
Combined ratio	64.30%	59.50%	46.20%	43.20%
Specialty Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 200,733	$ 160,013	$ 569,722	$ 284,304
Net premiums written	132,420	139,867	392,511	243,782
Net premiums earned	137,168	155,584	292,486	250,460
Net claims and claim expenses incurred	67,701	86,062	159,553	125,650
Acquisition expenses	34,127	28,251	75,852	48,940
Operational expenses	19,959	18,747	41,732	32,037
Underwriting income (loss)	15,381	22,524	15,349	43,833
Net claims and claim expenses incurred – current accident year	85,117	104,315	173,495	153,579
Net claims and claim expenses incurred – prior accident years	(17,416)	(18,253)	(13,942)	(27,929)
Net claims and claim expenses incurred – total	$ 67,701	$ 86,062	$ 159,553	$ 125,650
Net claims and claim expense ratio – current accident year	62.10%	67.00%	59.30%	61.30%
Net claims and claim expense ratio – prior accident years	(12.70%)	(11.70%)	(4.70%)	(11.10%)
Net claims and claim expense ratio – calendar year	49.40%	55.30%	54.60%	50.20%
Underwriting expense ratio	39.40%	30.20%	40.20%	32.30%
Combined ratio	88.80%	85.50%	94.80%	82.50%
Lloyd's | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 160,941	$ 116,618	$ 293,662	$ 246,748
Net premiums written	131,851	98,320	194,650	175,889
Net premiums earned	72,618	61,539	133,921	119,745
Net claims and claim expenses incurred	43,832	27,683	70,848	57,526
Acquisition expenses	18,651	14,210	32,938	28,903
Operational expenses	12,408	13,719	26,542	25,659
Underwriting income (loss)	(2,273)	5,927	3,593	7,657
Net claims and claim expenses incurred – current accident year	41,567	30,771	67,515	56,381
Net claims and claim expenses incurred – prior accident years	2,265	(3,088)	3,333	1,145
Net claims and claim expenses incurred – total	$ 43,832	$ 27,683	$ 70,848	$ 57,526
Net claims and claim expense ratio – current accident year	57.20%	50.00%	50.40%	47.10%
Net claims and claim expense ratio – prior accident years	3.20%	(5.00%)	2.50%	0.90%
Net claims and claim expense ratio – calendar year	60.40%	45.00%	52.90%	48.00%
Underwriting expense ratio	42.70%	45.40%	44.40%	45.60%
Combined ratio	103.10%	90.40%	97.30%	93.60%
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	86	223	3	51
Acquisition expenses	0	(109)	0	256
Operational expenses	21	117	81	145
Underwriting income (loss)	(107)	(231)	(84)	(541)
Net investment income	54,124	38,604	82,987	78,311
Net foreign exchange losses	(690)	(1,740)	(2,382)	(4,870)
Equity in earnings of other ventures	6,022	6,160	7,633	11,455
Other income	2,654	1,427	6,733	2,966
Net realized and unrealized gains (losses) on investments	69,772	(26,712)	131,425	15,037
Corporate expenses	(5,752)	(12,868)	(13,977)	(58,401)
Interest expense	(10,536)	(9,862)	(21,074)	(15,178)
Income tax (expense) benefit	(6,612)	1,842	(9,356)	49,746
Net income attributable to redeemable noncontrolling interests	(30,635)	(12,167)	(75,226)	(51,829)
Dividends on preference shares	(5,596)	(5,596)	(11,191)	(11,191)
Net claims and claim expenses incurred – current accident year	0	0	0	0
Net claims and claim expenses incurred – prior accident years	86	223	3	51
Net claims and claim expenses incurred – total	$ 86	$ 223	$ 3	51
Intersegment Eliminations
Segment Reporting Information [Line Items]
Gross premiums written				$ 100