Schedule II. Condensed Financial Information Of Registrant (Statements of Comprehensive Income (Loss)) (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	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 42,962	$ 45,887	$ 377,043	$ 282,906	$ (74,717)	$ 42,389	$ 197,384	$ 62,308	$ 748,798	$ 227,364	$ (222,389)
Change in net unrealized gains on investments, net of tax									2,173	(1,657)	(909)
Foreign currency translation adjustments, net of tax									(2,679)	0	0
Comprehensive income (loss) attributable to RenaissanceRe									748,292	225,707	(223,298)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									748,798	227,364	(222,389)
Change in net unrealized gains on investments, net of tax									2,173	(1,657)	(909)
Foreign currency translation adjustments, net of tax									(2,679)	0		$ 0
Comprehensive income (loss) attributable to RenaissanceRe									$ 748,292	$ 225,707	$ (223,298)