LOSS AND LOSS ADJUSTMENT RESERVES - (Schedule of Reconciliation of Net Incurred and Paid Development) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Abstract]
Total liabilities for unpaid losses and LAE, net of reinsurance	$ 179,030	$ 156,324
Reinsurance Recoverables on Unpaid Losses, Gross to Net [Abstract]
Total reinsurance recoverables	358,128	164,429
Unallocated loss adjustment expenses	3,209	3,609
Unfavorable loss and LAE reserve	540,367	324,362	$ 296,230	$ 230,515
Homeowners
Liability for Claims and Claims Adjustment Expense [Abstract]
Total liabilities for unpaid losses and LAE, net of reinsurance	149,314	137,168
Reinsurance Recoverables on Unpaid Losses, Gross to Net [Abstract]
Total reinsurance recoverables	353,741	160,578
Unfavorable loss and LAE reserve	149,314
Commercial general liability
Liability for Claims and Claims Adjustment Expense [Abstract]
Total liabilities for unpaid losses and LAE, net of reinsurance	28,328	17,014
Reinsurance Recoverables on Unpaid Losses, Gross to Net [Abstract]
Total reinsurance recoverables	0	500
Unfavorable loss and LAE reserve	28,328
Automobile
Liability for Claims and Claims Adjustment Expense [Abstract]
Total liabilities for unpaid losses and LAE, net of reinsurance	1,388	2,142
Reinsurance Recoverables on Unpaid Losses, Gross to Net [Abstract]
Total reinsurance recoverables	1,424	3,228
Unfavorable loss and LAE reserve	1,388
Flood
Liability for Claims and Claims Adjustment Expense [Abstract]
Total liabilities for unpaid losses and LAE, net of reinsurance	0	0
Reinsurance Recoverables on Unpaid Losses, Gross to Net [Abstract]
Total reinsurance recoverables	$ 2,963	$ 123