Condensed Consolidating Financial Information Provided in Connection with Outstanding Debt of Subsidiaries (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	$ 349,111	$ 321,023
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	4,813,208	5,163,972
Purchases of fixed maturity investments trading	(5,014,011)	(5,451,362)
Net purchases of equity investments trading	(34,298)	46,305
Net (purchases) sales of short term investments	(1,062,422)	276,075
Net purchases of other investments	(111,921)	2,551
Net purchases of investments in other ventures	(20,952)	0
Return of investment from investment in other ventures	8,464	20,000
Dividends and return of capital from subsidiaries	0	0
Contributions to subsidiaries	0	0
Due (from) to subsidiary	0	0
Net cash (used in) provided by investing activities	(1,421,932)	57,541
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	(26,468)	(25,877)
Dividends paid – preference shares	(11,191)	(11,191)
Issuance of preference shares, net of expenses	242,371	0
RenaissanceRe common share repurchases	0	(145,940)
Net repayment of debt		(250,000)
Net issuance of debt	0	295,866
Net third party redeemable noncontrolling interest share transactions	64,534	(33,655)
Taxes paid on withholding shares	(7,044)	(11,251)
Net cash provided by (used in) financing activities	262,202	(182,048)
Effect of exchange rate changes on foreign currency cash	(2,501)	5,477
Net (decrease) increase in cash and cash equivalents	(813,120)	201,993
Cash and cash equivalents, beginning of period	1,361,592	421,157
Cash and cash equivalents, end of period	548,472	623,150
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	1,213	(8,931)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	62,334	46,475
Purchases of fixed maturity investments trading	(46,047)	(45,174)
Net purchases of equity investments trading	(675)	(89)
Net (purchases) sales of short term investments	(154)	(1,351)
Net purchases of other investments	0	0
Net purchases of investments in other ventures	0
Return of investment from investment in other ventures	0	0
Dividends and return of capital from subsidiaries	0	9,175
Contributions to subsidiaries	(16,848)	0
Due (from) to subsidiary	50	9
Net cash (used in) provided by investing activities	(1,340)	9,045
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
Issuance of preference shares, net of expenses	0
RenaissanceRe common share repurchases		0
Net repayment of debt		0
Net issuance of debt		0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash provided by (used in) financing activities	0	0
Effect of exchange rate changes on foreign currency cash	0	0
Net (decrease) increase in cash and cash equivalents	(127)	114
Cash and cash equivalents, beginning of period	139	162
Cash and cash equivalents, end of period	12	276
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		(5,017)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading		289,741
Purchases of fixed maturity investments trading		(143,991)
Net purchases of equity investments trading		85,324
Net (purchases) sales of short term investments		41,299
Net purchases of other investments		0
Return of investment from investment in other ventures		0
Dividends and return of capital from subsidiaries		0
Contributions to subsidiaries		0
Due (from) to subsidiary		(41)
Net cash (used in) provided by investing activities		272,332
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares		0
Dividends paid – preference shares		0
RenaissanceRe common share repurchases		0
Net repayment of debt		(250,000)
Net issuance of debt		0
Net third party redeemable noncontrolling interest share transactions		0
Taxes paid on withholding shares		0
Net cash provided by (used in) financing activities		(250,000)
Effect of exchange rate changes on foreign currency cash		0
Net (decrease) increase in cash and cash equivalents		17,315
Cash and cash equivalents, beginning of period		6,671
Cash and cash equivalents, end of period		23,986
Reportable Legal Entities | RenaissanceRe Finance, Inc. (Subsidiary Issuer)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(32,605)	(27,713)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	35,946	15,449
Purchases of fixed maturity investments trading	(16,397)	(265,787)
Net purchases of equity investments trading	0	0
Net (purchases) sales of short term investments	(5,001)	(28,934)
Net purchases of other investments	0	0
Net purchases of investments in other ventures	0
Return of investment from investment in other ventures	0	0
Dividends and return of capital from subsidiaries	0	17,975
Contributions to subsidiaries	0	(9,175)
Due (from) to subsidiary	21,333	1,278
Net cash (used in) provided by investing activities	35,881	(269,194)
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
Issuance of preference shares, net of expenses	0
RenaissanceRe common share repurchases		0
Net repayment of debt		0
Net issuance of debt		295,866
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	0	0
Net cash provided by (used in) financing activities	0	295,866
Effect of exchange rate changes on foreign currency cash	0	0
Net (decrease) increase in cash and cash equivalents	3,276	(1,041)
Cash and cash equivalents, beginning of period	1,469	9,397
Cash and cash equivalents, end of period	4,745	8,356
Reportable Legal Entities | RenaissanceRe Holdings Ltd. (Parent Guarantor)
Cash flows (used in) provided by operating activities
Net cash (used in) provided by operating activities	(7,183)	(11,924)
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	120,555	53,654
Purchases of fixed maturity investments trading	(246,764)	(105,523)
Net purchases of equity investments trading	0	0
Net (purchases) sales of short term investments	56,048	298,768
Net purchases of other investments	0	0
Net purchases of investments in other ventures	0
Return of investment from investment in other ventures	0	0
Dividends and return of capital from subsidiaries	278,864	167,111
Contributions to subsidiaries	(250,238)	(200,000)
Due (from) to subsidiary	(161,104)	(12,477)
Net cash (used in) provided by investing activities	(202,639)	201,533
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	(26,468)	(25,877)
Dividends paid – preference shares	(11,191)	(11,191)
Issuance of preference shares, net of expenses	242,371
RenaissanceRe common share repurchases		(145,940)
Net repayment of debt		0
Net issuance of debt		0
Net third party redeemable noncontrolling interest share transactions	0	0
Taxes paid on withholding shares	(7,044)	(11,251)
Net cash provided by (used in) financing activities	197,668	(194,259)
Effect of exchange rate changes on foreign currency cash	0	0
Net (decrease) increase in cash and cash equivalents	(12,154)	(4,650)
Cash and cash equivalents, beginning of period	14,656	7,067
Cash and cash equivalents, end of period	2,502	2,417
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	387,686	374,608
Cash flows (used in) provided by investing activities
Proceeds from sales and maturities of fixed maturity investments trading	4,594,373	4,758,653
Purchases of fixed maturity investments trading	(4,704,803)	(4,890,887)
Net purchases of equity investments trading	(33,623)	(38,930)
Net (purchases) sales of short term investments	(1,113,315)	(33,707)
Net purchases of other investments	(111,921)	2,551
Net purchases of investments in other ventures	(20,952)
Return of investment from investment in other ventures	8,464	20,000
Dividends and return of capital from subsidiaries	(278,864)	(194,261)
Contributions to subsidiaries	267,086	209,175
Due (from) to subsidiary	139,721	11,231
Net cash (used in) provided by investing activities	(1,253,834)	(156,175)
Cash flows provided by (used in) financing activities
Dividends paid – RenaissanceRe common shares	0	0
Dividends paid – preference shares	0	0
Issuance of preference shares, net of expenses	0
RenaissanceRe common share repurchases		0
Net repayment of debt		0
Net issuance of debt		0
Net third party redeemable noncontrolling interest share transactions	64,534	(33,655)
Taxes paid on withholding shares	0	0
Net cash provided by (used in) financing activities	64,534	(33,655)
Effect of exchange rate changes on foreign currency cash	(2,501)	5,477
Net (decrease) increase in cash and cash equivalents	(804,115)	190,255
Cash and cash equivalents, beginning of period	1,345,328	397,860
Cash and cash equivalents, end of period	$ 541,213	$ 588,115