Income Taxes - Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
20% of net unearned premiums	$ 75,394	$ 67,285
Discounting of loss reserves and salvage and subrogation recoverable for tax purposes	25,340	21,606
Expense accruals	11,262	11,578
Tax asset on net unrealized loss on securities carried at fair value	166	22,802
Other deferred tax assets	8,743	6,511
Total gross deferred tax assets	120,905	129,782
Deferred tax liabilities:
Deferred policy acquisition costs	(61,707)	(55,960)
Tax depreciation in excess of book depreciation	(6,801)	(11,029)
Undistributed earnings of insurance subsidiaries	(1,511)	(1,898)
Tax amortization in excess of book amortization	(8,904)	(7,466)
Other deferred tax liabilities	(8,969)	(10,526)
Total gross deferred tax liabilities	(87,892)	(86,879)
Net deferred tax assets	$ 33,013	$ 42,903