Related-Party Transactions (Premiums And Losses Ceded By The Company To Affiliate) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Mt. Logan Re Segregated Accounts [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums	$ 63,223	$ 60,817
Ceded earned premiums	44,822	50,090
Ceded losses and LAE	34,623	15,807
Assumed written premiums		3,043
Assumed earned premiums		3,043
Assumed losses and LAE
Bermuda Re [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums	51,473	132,320
Ceded earned premiums	52,524	136,158
Ceded losses and LAE	11,733	193,551
Everest International [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums
Ceded earned premiums
Ceded losses and LAE	10
Everest Canada [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums
Assumed earned premiums
Assumed losses and LAE	(1,601)	2,973
Lloyd's Syndicate [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums	(9,209)	(2,682)
Assumed earned premiums	(18,827)	4,886
Assumed losses and LAE	$ (7,918)	$ 6,585