General - Effects of Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Premiums Written
Direct	$ 1,237,200	$ 1,057,100	$ 3,395,200	$ 3,109,500
Premiums Earned
Ceded	30,900	22,800	78,100	57,400
Net	1,090,311	996,939	3,129,483	2,947,000
Property & Casualty
Premiums Written
Direct	1,230,024	1,049,088	3,374,477	3,086,222
Ceded	(30,889)	(22,805)	(78,463)	(57,776)
Assumed	195	138	15,293	10,582
Net	1,199,330	1,026,421	3,311,307	3,039,028
Premiums Earned
Direct	1,110,013	1,009,829	3,174,296	2,974,651
Ceded	(30,917)	(22,825)	(78,114)	(57,383)
Assumed	3,883	2,684	11,630	8,142
Net	$ 1,082,979	$ 989,688	$ 3,107,812	$ 2,925,410