Loss And Loss Adjustment Expense Reserves (Activity In The Reserves For Losses And Loss Adjustment Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves at January 1	$ 1,991,304	$ 1,921,255	$ 1,829,412
Reissuance recoverables on unpaid losses, beginning of period	54,461	76,100	180,859
Net reserves at January 1	1,936,843	1,845,155	1,648,553
Incurred losses and loss adjustment expenses related to:
Current year	2,786,246	2,372,364	2,696,230
Prior years	(26,091)	22,979	9,794
Total incurred losses and loss adjustment expenses	2,760,155	2,395,343	2,706,024
Loss and loss adjustment expense payments related to:
Current year	1,601,998	1,366,661	1,651,550
Prior years	909,949	937,143	857,872
Total payments	2,511,947	2,303,804	2,509,422
Net reserves at December 31	2,185,051	1,936,843	1,845,155
Reissuance recoverables on unpaid losses, end of period	41,379	54,461	76,100
Gross reserves at December 31	2,226,430	1,991,304	1,921,255
Cumulative Effect, Period of Adoption, Adjustment
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Reissuance recoverables on unpaid losses, beginning of period	0	(149)	0
Loss and loss adjustment expense payments related to:
Reissuance recoverables on unpaid losses, end of period		0	(149)
Cumulative Effect, Period of Adoption, Adjusted Balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Reissuance recoverables on unpaid losses, beginning of period	$ 54,461	75,951	180,859
Net reserves at January 1		1,845,304
Loss and loss adjustment expense payments related to:
Net reserves at December 31			1,845,304
Reissuance recoverables on unpaid losses, end of period		$ 54,461	$ 75,951