Reserves For Losses And LAE (Summary Of Incurred Losses With Respect To A&E Reserves On Both Gross And Net Of Reinsurance Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reserves For Losses And LAE [Abstract]
Gross basis: Beginning of period reserves	$ 347,495	$ 448,993	$ 441,111
Gross basis: Incurred losses	2,071	(2,473)	90,009
Gross basis: Paid losses	(91,645)	(99,026)	(82,126)
Gross basis: End of period reserves	257,921	347,495	448,993
Net basis: Beginning of period reserves	223,548	269,153	274,409
Net basis: Incurred losses			25,194
Net basis: Paid losses	(26,974)	(45,605)	(30,451)
Net basis: End of period reserves	$ 196,574	$ 223,548	$ 269,153