Earnings Per Share (Computation Of Basic And Diluted Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net income available to RenaissanceRe common shareholders	$ 69,436	$ 146,825	$ 136,325	$ 127,995	$ 92,206	$ 75,529	$ 73,233	$ 167,843	$ 480,581	$ 408,811	$ 510,337
Amount allocated to participating common shareholders									(5,666)	(4,721)	(6,760)
Net income allocated to RenaissanceRe common shareholders									$ 474,915	$ 404,090	$ 503,577
Denominator:
Denominator for basic income per RenaissanceRe common share - weighted average common shares (In shares)	40,474	40,513	41,693	42,577	43,131	44,564	45,303	39,631	41,314	43,157	39,425
Per common share equivalents of employee stock options and performance shares (In shares)									245	369	543
Denominator for diluted income per RenaissanceRe common share - adjusted weighted average common shares and assumed conversions (In shares)	40,707	40,733	41,885	42,912	43,513	44,913	45,657	40,021	41,559	43,526	39,968
Basic income per RenaissanceRe common share (In dollars per share)	$ 1.70	$ 3.58	$ 3.23	$ 2.97	$ 2.11	$ 1.68	$ 1.60	$ 4.18	$ 11.50	$ 9.36	$ 12.77
Diluted income per RenaissanceRe common share (In dollars per share)	$ 1.69	$ 3.56	$ 3.22	$ 2.95	$ 2.09	$ 1.66	$ 1.59	$ 4.14	$ 11.43	$ 9.28	$ 12.60