Condensed Consolidating Financial Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	$ 621,702	$ 380,365
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	7,663,002	6,509,019
Purchases of fixed maturity investments trading	(7,798,285)	(6,744,838)
Proceeds from sales and maturities of fixed maturity investments available for sale	0	5,931
Net sales of equity investments trading	61,571	183,112
Net (purchases) sales of short term investments	(146,326)	128,869
Net sales (purchases) of other investments	5,181	(56,765)
Net sales of other assets	0	400
Dividends and return of capital from subsidiaries	0	0
Contributions to subsidiaries	0	0
Due to (from) subsidiary	0	0
Net cash (used in) provided by investing activities	(214,857)	25,728
Cash flows used in financing activities
Dividends paid – RenaissanceRe common shares	(38,624)	(38,886)
Dividends paid – preference shares	(16,786)	(16,786)
RenaissanceRe common share repurchases	(188,591)	(309,434)
Issuance of debt, net of expenses	295,866	0
Repayment of debt	(250,000)	0
Net third party redeemable noncontrolling interest share transactions	(44,193)	(45,496)
Taxes paid on withholding shares	(13,694)	(10,362)
Net cash used in financing activities	(256,022)	(420,964)
Effect of exchange rate changes on foreign currency cash	9,596	1,316
Net increase (decrease) in cash and cash equivalents	160,419	(13,555)
Cash and cash equivalents, beginning of period	421,157	506,885
Cash and cash equivalents, end of period	581,576	493,330
RenRe North America Holdings Inc. (Subsidiary Issuer)
Cash flows used in financing activities
Repayment of debt	0
Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Cash flows used in financing activities
Repayment of debt	(250,000)
RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Cash flows used in financing activities
Repayment of debt	0
RenaissanceRe Holdings Ltd. (Parent Guarantor)
Cash flows used in financing activities
Repayment of debt	0
Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Cash flows used in financing activities
Repayment of debt	0
Reportable Legal Entities | RenRe North America Holdings Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(8,209)	1,847
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	74,455	62,959
Purchases of fixed maturity investments trading	(69,168)	(115,849)
Proceeds from sales and maturities of fixed maturity investments available for sale		0
Net sales of equity investments trading	(1,708)	(2,392)
Net (purchases) sales of short term investments	(4,495)	67,986
Net sales (purchases) of other investments	0	0
Net sales of other assets		0
Dividends and return of capital from subsidiaries	9,175	2,900
Contributions to subsidiaries	0	0
Due to (from) subsidiary	14	(22,502)
Net cash (used in) provided by investing activities	8,273	(6,898)
Cash flows used in financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
RenaissanceRe common share repurchases	0	0
Issuance of debt, net of expenses	0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash used in financing activities	0	0
Effect of exchange rate changes on foreign currency cash	0	0
Net increase (decrease) in cash and cash equivalents	64	(5,051)
Cash and cash equivalents, beginning of period	162	5,908
Cash and cash equivalents, end of period	226	857
Reportable Legal Entities | Platinum Underwriters Finance, Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(2,262)	(11,062)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	289,741	113,947
Purchases of fixed maturity investments trading	(143,991)	(259,165)
Proceeds from sales and maturities of fixed maturity investments available for sale		0
Net sales of equity investments trading	85,324	192,911
Net (purchases) sales of short term investments	41,299	(41,881)
Net sales (purchases) of other investments	0	0
Net sales of other assets		0
Dividends and return of capital from subsidiaries	0	0
Contributions to subsidiaries	(26,649)	0
Due to (from) subsidiary	(123)	(108)
Net cash (used in) provided by investing activities	245,601	5,704
Cash flows used in financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
RenaissanceRe common share repurchases	0	0
Issuance of debt, net of expenses	0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash used in financing activities	(250,000)	0
Effect of exchange rate changes on foreign currency cash	0	0
Net increase (decrease) in cash and cash equivalents	(6,661)	(5,358)
Cash and cash equivalents, beginning of period	6,671	7,103
Cash and cash equivalents, end of period	10	1,745
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(343,093)	(35,171)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	279,830	0
Purchases of fixed maturity investments trading	(270,785)	0
Proceeds from sales and maturities of fixed maturity investments available for sale		0
Net sales of equity investments trading	0	0
Net (purchases) sales of short term investments	(305)	0
Net sales (purchases) of other investments	0	0
Net sales of other assets		0
Dividends and return of capital from subsidiaries	41,866	9,300
Contributions to subsidiaries	(9,175)	0
Due to (from) subsidiary	4,062	27,724
Net cash (used in) provided by investing activities	45,493	37,024
Cash flows used in financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
RenaissanceRe common share repurchases	0	0
Issuance of debt, net of expenses	295,866
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash used in financing activities	295,866	0
Effect of exchange rate changes on foreign currency cash	0	0
Net increase (decrease) in cash and cash equivalents	(1,734)	1,853
Cash and cash equivalents, beginning of period	9,397	677
Cash and cash equivalents, end of period	7,663	2,530
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(6,870)	(7,644)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	106,761	272,710
Purchases of fixed maturity investments trading	(118,402)	(336,345)
Proceeds from sales and maturities of fixed maturity investments available for sale		0
Net sales of equity investments trading	0	0
Net (purchases) sales of short term investments	205,864	122,656
Net sales (purchases) of other investments	0	0
Net sales of other assets		0
Dividends and return of capital from subsidiaries	285,515	408,189
Contributions to subsidiaries	(500,000)	(91,001)
Due to (from) subsidiary	290,130	(3,497)
Net cash (used in) provided by investing activities	269,868	372,712
Cash flows used in financing activities
Dividends paid – RenaissanceRe common shares	(38,624)	(38,886)
Dividends paid – preference shares	(16,786)	(16,786)
RenaissanceRe common share repurchases	(188,591)	(309,434)
Issuance of debt, net of expenses	0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	(13,694)	0
Net cash used in financing activities	(257,695)	(365,106)
Effect of exchange rate changes on foreign currency cash	0	0
Net increase (decrease) in cash and cash equivalents	5,303	(38)
Cash and cash equivalents, beginning of period	7,067	10,185
Cash and cash equivalents, end of period	12,370	10,147
Reportable Legal Entities | Other RenaissanceRe Holdings Ltd. Subsidiaries And Eliminations (Non-Guarantor Subsidiaries)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	982,136	432,395
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	6,912,215	6,059,403
Purchases of fixed maturity investments trading	(7,195,939)	(6,033,479)
Proceeds from sales and maturities of fixed maturity investments available for sale		5,931
Net sales of equity investments trading	(22,045)	(7,407)
Net (purchases) sales of short term investments	(388,689)	(19,892)
Net sales (purchases) of other investments	5,181	(56,765)
Net sales of other assets		400
Dividends and return of capital from subsidiaries	(336,556)	(420,389)
Contributions to subsidiaries	535,824	91,001
Due to (from) subsidiary	(294,083)	(1,617)
Net cash (used in) provided by investing activities	(784,092)	(382,814)
Cash flows used in financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
RenaissanceRe common share repurchases	0	0
Issuance of debt, net of expenses	0
Net third party redeemable noncontrolling interest share transactions	(44,193)	(45,496)
Taxes paid on withholding shares	0	(10,362)
Net cash used in financing activities	(44,193)	(55,858)
Effect of exchange rate changes on foreign currency cash	9,596	1,316
Net increase (decrease) in cash and cash equivalents	163,447	(4,961)
Cash and cash equivalents, beginning of period	397,860	483,012
Cash and cash equivalents, end of period	$ 561,307	$ 478,051