Loss And Loss Adjustment Expense Reserves (Activity In The Reserves For Losses And Loss Adjustment Expenses) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves, beginning of period	$ 2,226,430	$ 1,991,304
Reinsurance recoverables on unpaid losses	41,377	54,460
Net reserves, beginning of period	2,185,053	1,936,844
Incurred losses and loss adjustment expenses related to:
Current year	1,597,354	1,298,981
Prior years	51,359	(15,409)
Total incurred losses and loss adjustment expenses	1,648,713	1,283,572
Loss and loss adjustment expense payments related to:
Current year	738,472	641,726
Prior years	735,058	539,871
Total payments	1,473,530	1,181,597
Net reserves, end of period	2,360,236	2,038,819
Reinsurance recoverables on unpaid losses, end of period	26,586	52,196
Gross reserves, end of period	$ 2,386,822	$ 2,091,015