Schedule II. Condensed Financial Information Of Registrant (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows (used in) provided by operating activities
Net income (loss) attributable to RenaissanceRe	$ 42,962	$ 45,887	$ 377,043	$ 282,906	$ (74,717)	$ 42,389	$ 197,384	$ 62,308	$ 748,798	$ 227,364	$ (222,389)
Less: equity in net (income) loss of subsidiaries									0	0	0
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Net realized and unrealized (gains) losses on investments	(17,897)	$ (31,938)	$ (194,003)	(170,645)	88,654	$ (13,630)	$ 17,901	82,144	(414,483)	175,069	(135,822)
Other									251,351	(223,280)	518,100
Net cash provided by operating activities									2,137,195	1,221,701	1,025,787
Cash flows used in investing activities
Proceeds from maturities and sales of fixed maturity investments trading									17,313,940	11,585,576	9,490,669
Purchases of fixed maturity investments trading									(17,919,343)	(12,489,972)	(10,093,532)
Net sales (purchases) of short term investments									(1,900,741)	(1,436,389)	364,011
Dividends and return of capital from subsidiaries									0	0	0
Net cash used in investing activities									(2,988,644)	(2,536,613)	(122,434)
Cash flows provided by financing activities
Dividends paid – RenaissanceRe common shares									(59,368)	(52,841)	(51,370)
Dividends paid – preference shares									(36,756)	(30,088)	(22,381)
Issuance of debt, net of expenses									396,411	0	295,866
RenaissanceRe common share repurchases									0	0	(188,591)
RenaissanceRe common share issuance									0	250,000	0
Issuance of preference shares, net of expenses									0	241,448	0
Taxes paid on withholding shares									(7,253)	(7,862)	(15,139)
Net cash provided by financing activities									1,120,117	1,066,340	28,860
Cash and cash equivalents, beginning of year				1,107,922				1,361,592	1,107,922	1,361,592	421,157
Cash and cash equivalents, end of year	1,379,068				1,107,922				1,379,068	1,107,922	1,361,592
Parent Company
Cash flows (used in) provided by operating activities
Net income (loss) attributable to RenaissanceRe									748,798	227,364	(222,389)
Less: equity in net (income) loss of subsidiaries									(773,419)	(240,495)	212,708
Loss before equity in net income of subsidiaries									(24,621)	(13,131)	(9,681)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Net realized and unrealized (gains) losses on investments									(12,393)	(633)	1,357
Other									34,153	30,951	29,442
Net cash provided by operating activities									(2,861)	17,187	21,118
Cash flows used in investing activities
Proceeds from maturities and sales of fixed maturity investments trading									306,579	384,818	261,601
Purchases of fixed maturity investments trading									(66,740)	(520,935)	(344,463)
Net sales (purchases) of short term investments									(116,499)	48,600	243,571
Dividends and return of capital from subsidiaries									1,400,944	672,098	478,496
Contributions to subsidiaries									(1,165,607)	(785,785)	(669,672)
Due to (from) subsidiary									(625,924)	(227,762)	294,419
Net cash used in investing activities									(267,247)	(428,966)	263,952
Cash flows provided by financing activities
Dividends paid – RenaissanceRe common shares									(59,368)	(52,841)	(51,370)
Dividends paid – preference shares									(36,756)	(30,088)	(22,381)
Issuance of debt, net of expenses									396,411	0	0
RenaissanceRe common share repurchases									0	0	(188,591)
RenaissanceRe common share issuance									0	250,000	0
Issuance of preference shares, net of expenses									0	241,448	0
Taxes paid on withholding shares									(7,253)	(7,862)	(15,139)
Net cash provided by financing activities									293,034	400,657	(277,481)
Net (decrease) increase in cash and cash equivalents									22,926	(11,122)	7,589
Cash and cash equivalents, beginning of year				$ 3,534				$ 14,656	3,534	14,656	7,067
Cash and cash equivalents, end of year	$ 26,460				$ 3,534				$ 26,460	$ 3,534	$ 14,656