Income Taxes - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Tax discounting of unpaid losses and settlement expenses	$ 22,637	$ 21,096
Unearned premium offset	23,080	19,862
Deferred compensation	3,469	2,829
Stock option expense	3,089	2,749
Lease liability	3,796	3,971
Other	367	389
Deferred tax assets before allowance	56,438	50,896
Total deferred tax assets	56,438	50,896
Deferred tax liabilities:
Net unrealized appreciation of securities	76,533	77,639
Deferred policy acquisition costs	21,746	18,569
Lease asset	3,101	3,402
Discounting of unpaid losses and settlement expenses - Tax Cuts and Jobs Act (TCJA) implementation offset	2,545	3,181
Fixed assets	3,518	3,439
Intangible assets	1,537	1,558
Undistributed earnings of unconsolidated investees	29,515	21,813
Other	1,452	1,530
Total deferred tax liabilities	139,947	131,131
Net deferred tax liability	$ (83,509)	$ (80,235)