Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement of Comprehensive (Loss) Income (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
Condensed Financial Statements, Captions [Line Items]
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
Change in net unrealized gains on investments									(909)	(975)	(1,308)
Comprehensive (loss) income									(355,580)	629,073	540,934
Net loss (income) attributable to redeemable noncontrolling interests									132,282	(127,086)	(111,050)
Comprehensive income attributable to redeemable noncontrolling interests									132,282	(127,086)	(111,050)
Comprehensive (loss) income attributable to RenaissanceRe									(223,298)	501,987	429,884
RenaissanceRe Holdings Ltd. (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Comprehensive (loss) income attributable to RenaissanceRe									(222,389)	502,962	431,192
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(222,389)	502,962	431,192
Change in net unrealized gains on investments									0	0	0
Comprehensive (loss) income									(222,389)	502,962	431,192
Net loss (income) attributable to redeemable noncontrolling interests									0	0	0
Comprehensive income attributable to redeemable noncontrolling interests									0	0	0
Comprehensive (loss) income attributable to RenaissanceRe									(222,389)	502,962	431,192
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(285,838)	681,025	579,273
Change in net unrealized gains on investments									(909)	(975)	(1,308)
Comprehensive (loss) income									(286,747)	680,050	577,965
Net loss (income) attributable to redeemable noncontrolling interests									132,282	(127,086)	(111,050)
Comprehensive income attributable to redeemable noncontrolling interests									132,282	(127,086)	(111,050)
Comprehensive (loss) income attributable to RenaissanceRe									(154,465)	552,964	466,915
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(5,926)	8,002	27,209
Change in net unrealized gains on investments									0	0	0
Comprehensive (loss) income									(5,926)	8,002	27,209
Net loss (income) attributable to redeemable noncontrolling interests									0	0	0
Comprehensive income attributable to redeemable noncontrolling interests									0	0	0
Comprehensive (loss) income attributable to RenaissanceRe									(5,926)	8,002	27,209
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									30,596	29,591	33,849
Change in net unrealized gains on investments									0	0	0
Comprehensive (loss) income									30,596	29,591	33,849
Net loss (income) attributable to redeemable noncontrolling interests									0	0	0
Comprehensive income attributable to redeemable noncontrolling interests									0	0	0
Comprehensive (loss) income attributable to RenaissanceRe									30,596	29,591	33,849
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									(38,871)	1,922	61,429
Change in net unrealized gains on investments									0	0	0
Comprehensive (loss) income									(38,871)	1,922	61,429
Net loss (income) attributable to redeemable noncontrolling interests									0	0	0
Comprehensive income attributable to redeemable noncontrolling interests									0	0	0
Comprehensive (loss) income attributable to RenaissanceRe									(38,871)	1,922	61,429
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Net (loss) income									167,757	(593,454)	(590,710)
Change in net unrealized gains on investments									0	0	0
Comprehensive (loss) income									167,757	(593,454)	(590,710)
Net loss (income) attributable to redeemable noncontrolling interests									0	0	0
Comprehensive income attributable to redeemable noncontrolling interests									0	0	0
Comprehensive (loss) income attributable to RenaissanceRe									$ 167,757	$ (593,454)	$ (590,710)