SCHEDULE VI - SUPPLEMENTAL INFORMATION CONCERNING PROPERTY/CASUALTY INSURANCE OPERATIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Information, Property-Casualty Insurance [Abstract]
Deferred policy acquisition costs	$ 8,496	$ 6,568	$ 5,608
Reserves for unpaid claims and claim adjustment expenses	988,305	865,339	680,274
Discount if any deducted from reserves	0	0	0
Unearned premiums	74,810	71,625	53,085
Earned premiums	447,288	432,880	328,145
Net investment income	26,249	22,048	18,095
Claims and claim adjustment expenses incurred related to current year	349,018	329,078	228,303
Claims and claim adjustment expenses incurred related to prior years	(550)	16,786	19,215
Amortization of deferred policy acquisition costs	81,734	78,105	70,574
Paid claims and claim adjustment expenses	247,872	228,591	200,154
Net premiums written	$ 452,242	$ 444,398	$ 353,389