Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Net premiums earned	$ 421,473	$ 547,792	$ 382,265	$ 366,045	$ 351,901	$ 346,521	$ 351,402	$ 353,606	$ 1,717,575	$ 1,403,430	$ 1,400,551
Net investment income	73,464	40,257	54,163	54,325	47,316	51,423	54,124	28,863	222,209	181,726	152,567
Net foreign exchange gains (losses)	(490)	(156)	3,109	8,165	(5,420)	(5,986)	(690)	(1,692)	10,628	(13,788)	(3,051)
Equity in (losses) earnings of other ventures	2,200	1,794	5,543	(1,507)	4,960	(11,630)	6,022	1,611	8,030	963	20,481
Other income	2,362	2,996	2,392	1,665	5,177	2,268	2,654	4,079	9,415	14,178	13,472
Net realized and unrealized gains (losses) on investments	(7,716)	42,052	58,113	43,373	(49,967)	59,870	69,772	61,653	135,822	141,328	(68,918)
Total revenues	491,293	634,735	505,585	472,066	353,967	442,466	483,284	448,120	2,103,679	1,727,837	1,515,102
Expenses
Net claims and claim expenses incurred	304,064	1,221,696	142,587	193,081	123,901	112,575	167,750	126,605	1,861,428	530,831	448,238
Acquisition expenses	98,598	76,761	88,251	83,282	74,146	80,580	69,005	65,592	346,892	289,323	238,592
Operational expenses	29,192	42,537	41,766	47,283	49,948	40,493	51,073	56,235	160,778	197,749	219,112
Corporate expenses	4,237	4,413	4,636	5,286	11,888	11,537	5,752	8,225	18,572	37,402	76,514
Interest expense	11,777	11,799	10,091	10,526	10,534	10,536	10,536	10,538	44,193	42,144	36,270
Total expenses	447,868	1,357,206	287,331	339,458	270,417	255,721	304,116	267,195	2,431,863	1,097,449	1,018,726
(Loss) income before equity in net income of subsidiaries and taxes									(328,184)	630,388	496,376
Equity in net (loss) income of subsidiaries									0	0	0
(Loss) income before taxes	43,425	(722,471)	218,254	132,608	83,550	186,745	179,168	180,925	(328,184)	630,388	496,376
Income tax (expense) benefit	(41,226)	18,977	(3,904)	(334)	7,700	1,316	(6,612)	(2,744)	(26,487)	(340)	45,866
Net (loss) income	2,199	(703,494)	214,350	132,274	91,250	188,061	172,556	178,181	(354,671)	630,048	542,242
Net (income) loss attributable to redeemable noncontrolling interests	(56)	204,277	(37,612)	(34,327)	(16,219)	(35,641)	(30,635)	(44,591)	132,282	(127,086)	(111,050)
Net (loss) income attributable to RenaissanceRe	2,143	(499,217)	176,738	97,947	75,031	152,420	141,921	133,590	(222,389)	502,962	431,192
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 (loss) income (attributable) available to RenaissanceRe common shareholders	$ (3,452)	$ (504,812)	$ 171,142	$ 92,352	$ 69,436	$ 146,825	$ 136,325	$ 127,995	(244,770)	480,581	408,811
RenaissanceRe Holdings Ltd. (Parent Guarantor)
Revenues
Net investment income									23,109	24,178	15,391
Net foreign exchange gains (losses)									(1)	(2)	4
Other income									0	(772)	663
Net realized and unrealized gains (losses) on investments									(1,357)	4,151	(2,080)
Total revenues									21,751	27,555	13,978
Expenses
Operational expenses									11,314	13,716	4,249
Corporate expenses									18,546	26,848	40,808
Interest expense									1,572	562	1,255
Total expenses									31,432	41,126	46,312
(Loss) income before equity in net income of subsidiaries and taxes									(9,681)	(13,571)	(32,334)
Equity in net (loss) income of subsidiaries									(212,708)	516,533	463,526
Net (loss) income attributable to RenaissanceRe									(222,389)	502,962	431,192
Dividends on preference shares									(22,381)	(22,381)	(22,381)
Net (loss) income (attributable) available to RenaissanceRe common shareholders									(244,770)	480,581	408,811
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Revenues
Net premiums earned									0	0	0
Net investment income									23,109	24,178	15,391
Net foreign exchange gains (losses)									(1)	(2)	4
Equity in (losses) earnings of other ventures									0	0	0
Other income									0	(772)	663
Net realized and unrealized gains (losses) on investments									(1,357)	4,151	(2,080)
Total revenues									21,751	27,555	13,978
Expenses
Net claims and claim expenses incurred									0	0	0
Acquisition expenses									0	0	0
Operational expenses									11,314	13,716	4,249
Corporate expenses									18,546	26,848	40,808
Interest expense									1,572	562	1,255
Total expenses									31,432	41,126	46,312
(Loss) income before equity in net income of subsidiaries and taxes									(9,681)	(13,571)	(32,334)
Equity in net (loss) income of subsidiaries									(212,708)	516,533	463,526
(Loss) income before taxes									(222,389)	502,962	431,192
Income tax (expense) benefit									0	0	0
Net (loss) income									(222,389)	502,962	431,192
Net (income) loss attributable to redeemable noncontrolling interests									0	0	0
Net (loss) income attributable to RenaissanceRe									(222,389)	502,962	431,192
Dividends on preference shares									(22,381)	(22,381)	(22,381)
Net (loss) income (attributable) available to RenaissanceRe common shareholders									(244,770)	480,581	408,811
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Revenues
Net premiums earned									1,717,575	1,403,430	1,400,551
Net investment income									219,490	175,407	144,642
Net foreign exchange gains (losses)									10,629	(13,786)	(3,055)
Equity in (losses) earnings of other ventures									8,253	963	20,481
Other income									9,415	14,950	13,472
Net realized and unrealized gains (losses) on investments									123,121	124,279	(64,804)
Total revenues									2,088,483	1,705,243	1,511,287
Expenses
Net claims and claim expenses incurred									1,861,428	530,831	448,238
Acquisition expenses									346,892	289,323	238,592
Operational expenses									141,572	176,041	207,802
Corporate expenses									26	10,344	35,391
Interest expense									10,075	10,062	7,677
Total expenses									2,359,993	1,016,601	937,700
(Loss) income before equity in net income of subsidiaries and taxes									(271,510)	688,642	573,587
Equity in net (loss) income of subsidiaries									0	0	0
(Loss) income before taxes									(271,510)	688,642	573,587
Income tax (expense) benefit									(14,328)	(7,617)	5,686
Net (loss) income									(285,838)	681,025	579,273
Net (income) loss attributable to redeemable noncontrolling interests									132,282	(127,086)	(111,050)
Net (loss) income attributable to RenaissanceRe									(153,556)	553,939	468,223
Dividends on preference shares									0	0	0
Net (loss) income (attributable) available to RenaissanceRe common shareholders									(153,556)	553,939	468,223
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Revenues
Net premiums earned									0	0	0
Net investment income									1,947	1,852	1,251
Net foreign exchange gains (losses)									0	0	0
Equity in (losses) earnings of other ventures									0	0	0
Other income									0	0	0
Net realized and unrealized gains (losses) on investments									9,621	4,659	566
Total revenues									11,568	6,511	1,817
Expenses
Net claims and claim expenses incurred									0	0	0
Acquisition expenses									0	0	0
Operational expenses									103	(112)	4,561
Corporate expenses									0	203	312
Interest expense									0	0	7,233
Total expenses									103	91	12,106
(Loss) income before equity in net income of subsidiaries and taxes									11,465	6,420	(10,289)
Equity in net (loss) income of subsidiaries									756	3,857	5,493
(Loss) income before taxes									12,221	10,277	(4,796)
Income tax (expense) benefit									(18,147)	(2,275)	32,005
Net (loss) income									(5,926)	8,002	27,209
Net (income) loss attributable to redeemable noncontrolling interests									0	0	0
Net (loss) income attributable to RenaissanceRe									(5,926)	8,002	27,209
Dividends on preference shares									0	0	0
Net (loss) income (attributable) available to RenaissanceRe common shareholders									(5,926)	8,002	27,209
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Revenues
Net premiums earned									0	0	0
Net investment income									1,373	3,989	4,063
Net foreign exchange gains (losses)									0	0	0
Equity in (losses) earnings of other ventures									0	0	0
Other income									0	0	0
Net realized and unrealized gains (losses) on investments									4,916	8,193	(2,600)
Total revenues									6,289	12,182	1,463
Expenses
Net claims and claim expenses incurred									0	0	0
Acquisition expenses									0	0	0
Operational expenses									85	296	3
Corporate expenses									0	0	3
Interest expense									2,461	5,906	4,922
Total expenses									2,546	6,202	4,928
(Loss) income before equity in net income of subsidiaries and taxes									3,743	5,980	(3,465)
Equity in net (loss) income of subsidiaries									28,028	25,073	35,329
(Loss) income before taxes									31,771	31,053	31,864
Income tax (expense) benefit									(1,175)	(1,462)	1,985
Net (loss) income									30,596	29,591	33,849
Net (income) loss attributable to redeemable noncontrolling interests									0	0	0
Net (loss) income attributable to RenaissanceRe									30,596	29,591	33,849
Dividends on preference shares									0	0	0
Net (loss) income (attributable) available to RenaissanceRe common shareholders									30,596	29,591	33,849
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Revenues
Net premiums earned									0	0	0
Net investment income									3,090	569	996
Net foreign exchange gains (losses)									0	0	0
Equity in (losses) earnings of other ventures									(223)	0	0
Other income									0	0	0
Net realized and unrealized gains (losses) on investments									(479)	46	0
Total revenues									2,388	615	996
Expenses
Net claims and claim expenses incurred									0	0	0
Acquisition expenses									0	0	0
Operational expenses									26,063	22,152	2,503
Corporate expenses									0	7	0
Interest expense									31,657	26,176	16,179
Total expenses									57,720	48,335	18,682
(Loss) income before equity in net income of subsidiaries and taxes									(55,332)	(47,720)	(17,686)
Equity in net (loss) income of subsidiaries									9,298	38,628	72,925
(Loss) income before taxes									(46,034)	(9,092)	55,239
Income tax (expense) benefit									7,163	11,014	6,190
Net (loss) income									(38,871)	1,922	61,429
Net (income) loss attributable to redeemable noncontrolling interests									0	0	0
Net (loss) income attributable to RenaissanceRe									(38,871)	1,922	61,429
Dividends on preference shares									0	0	0
Net (loss) income (attributable) available to RenaissanceRe common shareholders									(38,871)	1,922	61,429
Consolidating Adjustments
Revenues
Net premiums earned									0	0	0
Net investment income									(26,800)	(24,269)	(13,776)
Net foreign exchange gains (losses)									0	0	0
Equity in (losses) earnings of other ventures									0	0	0
Other income									0	0	(663)
Net realized and unrealized gains (losses) on investments									0	0	0
Total revenues									(26,800)	(24,269)	(14,439)
Expenses
Net claims and claim expenses incurred									0	0	0
Acquisition expenses									0	0	0
Operational expenses									(18,359)	(14,344)	(6)
Corporate expenses									0	0	0
Interest expense									(1,572)	(562)	(996)
Total expenses									(19,931)	(14,906)	(1,002)
(Loss) income before equity in net income of subsidiaries and taxes									(6,869)	(9,363)	(13,437)
Equity in net (loss) income of subsidiaries									174,626	(584,091)	(577,273)
(Loss) income before taxes									167,757	(593,454)	(590,710)
Income tax (expense) benefit									0	0	0
Net (loss) income									167,757	(593,454)	(590,710)
Net (income) loss attributable to redeemable noncontrolling interests									0	0	0
Net (loss) income attributable to RenaissanceRe									167,757	(593,454)	(590,710)
Dividends on preference shares									0	0	0
Net (loss) income (attributable) available to RenaissanceRe common shareholders									$ 167,757	$ (593,454)	$ (590,710)