Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Net premiums earned	$ 440,282	$ 366,045
Net investment income	56,476	54,325
Net foreign exchange (losses) gains	3,757	8,165
Equity in earnings (losses) of other ventures	857	(1,507)
Other (loss) income	(1,242)	1,665
Net realized and unrealized (losses) gains on investments	(82,144)	43,373
Total revenues	417,986	472,066
Expenses
Net claims and claim expenses incurred	171,703	193,081
Acquisition expenses	97,711	83,282
Operational expenses	41,272	47,283
Corporate expenses	6,733	5,286
Interest expense	11,767	10,526
Total expenses	329,186	339,458
(Loss) income before equity in net income (loss) of subsidiaries and taxes	88,800	132,608
Equity in net income (loss) of subsidiaries	0	0
Income before taxes	88,800	132,608
Income tax benefit (expense)	3,407	(334)
Net income	92,207	132,274
Net (income) loss attributable to redeemable noncontrolling interests	(29,899)	(34,327)
Net income attributable to RenaissanceRe	62,308	97,947
Dividends on preference shares	(5,595)	(5,595)
Net income available to RenaissanceRe common shareholders	56,713	92,352
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Revenues
Net premiums earned	0	0
Net investment income	513	426
Net foreign exchange (losses) gains	0	0
Equity in earnings (losses) of other ventures	0	0
Other (loss) income	0	0
Net realized and unrealized (losses) gains on investments	(1,286)	2,921
Total revenues	(773)	3,347
Expenses
Net claims and claim expenses incurred	0	0
Acquisition expenses	0	0
Operational expenses	10	24
Corporate expenses	0	0
Interest expense	0	0
Total expenses	10	24
(Loss) income before equity in net income (loss) of subsidiaries and taxes	(783)	3,323
Equity in net income (loss) of subsidiaries	834	1,086
Income before taxes	51	4,409
Income tax benefit (expense)	221	(1,098)
Net income	272	3,311
Net (income) loss attributable to redeemable noncontrolling interests	0	0
Net income attributable to RenaissanceRe	272	3,311
Dividends on preference shares	0	0
Net income available to RenaissanceRe common shareholders	272	3,311
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Revenues
Net premiums earned		0
Net investment income		841
Net foreign exchange (losses) gains		0
Equity in earnings (losses) of other ventures		0
Other (loss) income		0
Net realized and unrealized (losses) gains on investments		4,725
Total revenues		5,566
Expenses
Net claims and claim expenses incurred		0
Acquisition expenses		0
Operational expenses		50
Corporate expenses		0
Interest expense		1,476
Total expenses		1,526
(Loss) income before equity in net income (loss) of subsidiaries and taxes		4,040
Equity in net income (loss) of subsidiaries		9,843
Income before taxes		13,883
Income tax benefit (expense)		(1,308)
Net income		12,575
Net (income) loss attributable to redeemable noncontrolling interests		0
Net income attributable to RenaissanceRe		12,575
Dividends on preference shares		0
Net income available to RenaissanceRe common shareholders		12,575
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Revenues
Net premiums earned	0	0
Net investment income	1,234	269
Net foreign exchange (losses) gains	0	0
Equity in earnings (losses) of other ventures	1,211	(752)
Other (loss) income	0	0
Net realized and unrealized (losses) gains on investments	(259)	(26)
Total revenues	2,186	(509)
Expenses
Net claims and claim expenses incurred	0	0
Acquisition expenses	0	0
Operational expenses	11,070	7,979
Corporate expenses	0	0
Interest expense	9,252	6,542
Total expenses	20,322	14,521
(Loss) income before equity in net income (loss) of subsidiaries and taxes	(18,136)	(15,030)
Equity in net income (loss) of subsidiaries	(3,813)	16,498
Income before taxes	(21,949)	1,468
Income tax benefit (expense)	1,815	3,072
Net income	(20,134)	4,540
Net (income) loss attributable to redeemable noncontrolling interests	0	0
Net income attributable to RenaissanceRe	(20,134)	4,540
Dividends on preference shares	0	0
Net income available to RenaissanceRe common shareholders	(20,134)	4,540
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Revenues
Net premiums earned	0	0
Net investment income	6,035	5,457
Net foreign exchange (losses) gains	(3)	0
Equity in earnings (losses) of other ventures	0	0
Other (loss) income	0	(1)
Net realized and unrealized (losses) gains on investments	(661)	53
Total revenues	5,371	5,509
Expenses
Net claims and claim expenses incurred	0	0
Acquisition expenses	0	0
Operational expenses	1,313	3,298
Corporate expenses	3,684	5,208
Interest expense	1,108	140
Total expenses	6,105	8,646
(Loss) income before equity in net income (loss) of subsidiaries and taxes	(734)	(3,137)
Equity in net income (loss) of subsidiaries	62,426	101,353
Income before taxes	61,692	98,216
Income tax benefit (expense)	616	(269)
Net income	62,308	97,947
Net (income) loss attributable to redeemable noncontrolling interests	0	0
Net income attributable to RenaissanceRe	62,308	97,947
Dividends on preference shares	(5,595)	(5,595)
Net income available to RenaissanceRe common shareholders	56,713	92,352
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Revenues
Net premiums earned	440,282	366,045
Net investment income	56,305	53,583
Net foreign exchange (losses) gains	3,760	8,165
Equity in earnings (losses) of other ventures	(354)	(755)
Other (loss) income	(1,242)	1,666
Net realized and unrealized (losses) gains on investments	(79,938)	35,700
Total revenues	418,813	464,404
Expenses
Net claims and claim expenses incurred	171,703	193,081
Acquisition expenses	97,711	83,282
Operational expenses	37,933	42,058
Corporate expenses	3,049	78
Interest expense	2,515	2,508
Total expenses	312,911	321,007
(Loss) income before equity in net income (loss) of subsidiaries and taxes	105,902	143,397
Equity in net income (loss) of subsidiaries	0	0
Income before taxes	105,902	143,397
Income tax benefit (expense)	755	(731)
Net income	106,657	142,666
Net (income) loss attributable to redeemable noncontrolling interests	(29,899)	(34,327)
Net income attributable to RenaissanceRe	76,758	108,339
Dividends on preference shares	0	0
Net income available to RenaissanceRe common shareholders	76,758	108,339
Consolidating Adjustments
Revenues
Net premiums earned	0	0
Net investment income	(7,611)	(6,251)
Net foreign exchange (losses) gains	0	0
Equity in earnings (losses) of other ventures	0	0
Other (loss) income	0	0
Net realized and unrealized (losses) gains on investments	0	0
Total revenues	(7,611)	(6,251)
Expenses
Net claims and claim expenses incurred	0	0
Acquisition expenses	0	0
Operational expenses	(9,054)	(6,126)
Corporate expenses	0	0
Interest expense	(1,108)	(140)
Total expenses	(10,162)	(6,266)
(Loss) income before equity in net income (loss) of subsidiaries and taxes	2,551	15
Equity in net income (loss) of subsidiaries	(59,447)	(128,780)
Income before taxes	(56,896)	(128,765)
Income tax benefit (expense)	0	0
Net income	(56,896)	(128,765)
Net (income) loss attributable to redeemable noncontrolling interests	0	0
Net income attributable to RenaissanceRe	(56,896)	(128,765)
Dividends on preference shares	0	0
Net income available to RenaissanceRe common shareholders	$ (56,896)	$ (128,765)