Related-Party Transactions (Premiums And Losses Ceded By The Company To Affiliate) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Mt. Logan Re Segregated Accounts [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums	$ 51,289	$ 40,622	$ 114,512	$ 101,439
Ceded earned premiums	61,812	54,885	106,634	104,975
Ceded losses and LAE	30,159	92,100	64,781	107,907
Assumed written premiums		1,604		4,647
Assumed earned premiums		1,604		4,647
Assumed losses and LAE
Bermuda Re [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums	19,534	142,971	71,007	275,291
Ceded earned premiums	16,598	148,073	69,122	284,231
Ceded losses and LAE	(3,417)	(157,443)	8,316	36,108
Everest International [Member]
Effects of Reinsurance [Line Items]
Ceded written premiums
Ceded earned premiums
Ceded losses and LAE	(46)	(357)	(36)	(357)
Everest Canada [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums
Assumed earned premiums
Assumed losses and LAE	2,296	373	695	3,346
Lloyd's Syndicate [Member]
Effects of Reinsurance [Line Items]
Assumed written premiums	483	2,421	(8,726)	(261)
Assumed earned premiums	1,596	6,064	(17,231)	10,950
Assumed losses and LAE	$ 4,391	$ 1,441	$ (3,527)	$ 8,026