Schedule VI-Supplementary Information Concerning Property-Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Claims and claim adjustment expenses incurred related to:
Current accident year	$ 636,955	$ 582,065	$ 543,937
Prior accident years	(122,579)	(125,463)	(101,053)
Amortization of deferred acquisition costs	369,632	317,468	286,438
Consolidated Property-Casualty Insurance Operations
Supplemental Information For Property Casualty Insurance Underwriters [Line Items]
Deferred policy acquisition costs	127,859	103,553	88,425
Claims and claim adjustment expense reserves	2,315,637	2,043,555	1,750,049
Unearned premiums, gross	785,085	680,444	586,386
Net premiums earned	1,144,436	980,903	865,747
Net investment income	86,078	68,862	67,893
Claims and claim adjustment expenses incurred related to:
Current accident year	636,955	582,065	543,937
Prior accident years	(122,579)	(125,463)	(101,053)
Amortization of deferred acquisition costs	369,632	317,468	286,438
Paid claims and claims adjustment expenses	374,297	327,453	325,054
Net premiums written	$ 1,241,536	$ 1,057,533	$ 892,088