Reserves For Losses And LAE (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Reserves For Losses And LAE [Line Items]
Current year incurred losses	$ 4,106,331	$ 3,288,049
Catastrophe Losses [Member]
Reserves For Losses And LAE [Line Items]
Current year incurred losses	$ 837,400	341,000
Covid-19 [Member]
Reserves For Losses And LAE [Line Items]
Current year incurred losses		$ 104,800