Related-Party Transactions (Premiums And Losses Ceded By The Company To Affiliate) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Mt Logan Re [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums	$ 40,665	$ 81,371
Ceded earned premiums	42,484	65,988
Ceded losses and LAE	36,764	72,994
Bermuda Re [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums	92,439	70,853
Ceded earned premiums	92,438	70,877
Ceded losses and LAE	(1,845)	(30,104)
Assumed written premiums	2,257
Assumed earned premiums	3,439	61
Assumed losses and LAE	(194)	25
Everest International And Canada [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums
Assumed earned premiums
Assumed losses and LAE	8,055	59
Ireland Re [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums	2,302	2,923
Assumed earned premiums	2,512	1,948
Assumed losses and LAE	2,441
Ireland Insurance [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums	1,959	1,301
Assumed earned premiums	1,640	1,262
Assumed losses and LAE	6,391	698
Lloyd's Syndicate [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums	(7)	599
Assumed earned premiums	(7)	529
Assumed losses and LAE	$ 254	$ (1,582)