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
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income available to RenaissanceRe common shareholders	$ 92,352	$ 127,995
Amount allocated to participating common shareholders	(907)	(1,601)
Net income allocated to RenaissanceRe common shareholders	$ 91,445	$ 126,394
Denominator:
Denominator for basic income per RenaissanceRe common share - weighted average common shares (in shares)	40,408	42,577
Per common share equivalents of employee stock options and restricted shares (in shares)	215	335
Denominator for diluted income per RenaissanceRe common share - adjusted weighted average common shares and assumed conversions (in shares)	40,623	42,912
Net income available to RenaissanceRe common shareholders per common share – basic (in usd per share)	$ 2.26	$ 2.97
Net income available to RenaissanceRe common shareholders per common share – diluted (in usd per share)	$ 2.25	$ 2.95