Loss And Loss Adjustment Expense Reserves (Activity In The Reserves For Losses And Loss Adjustment Expenses) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 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	2,386,233	2,005,233
Prior years	49,942	(23,714)
Total incurred losses and loss adjustment expenses	2,436,175	1,981,519
Loss and loss adjustment expense payments related to:
Current year	1,267,535	1,088,285
Prior years	945,371	739,385
Total payments	2,212,906	1,827,670
Net reserves, end of period	2,408,322	2,090,693
Reinsurance recoverables on unpaid losses, end of period	24,412	51,428
Gross reserves, end of period	$ 2,432,734	$ 2,142,121