Schedule VI - Supplemental Information Concerning Property/Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Information Concerning Property/Casualty Insurance Operations [Abstract]
Deferred policy acquisition costs	$ 9,744	$ 8,496	$ 6,568
Reserves for unpaid claims adjustment expenses	1,089,669	988,305	865,339
Discount if any deducted from reserves	0	0	0
Unearned premiums	63,731	74,810	71,625
Earned premiums	445,515	447,288	432,880
Net investment income	25,422	26,249	22,048
Claims and claim adjustment expenses incurred related to current year	319,269	349,018	329,078
Claims and claim adjustment expenses incurred related to prior years	(311)	(550)	16,786
Amortization of deferred policy acquisition costs	79,947	81,734	78,105
Paid claims and claim adjustment expenses	243,657	247,872	228,591
Net premiums written	$ 441,000	$ 452,242	$ 444,398