LOSS AND LOSS ADJUSTMENT RESERVES - (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Catastrophe Claims [Line Items]
Current year			$ 358,952	$ 262,118	$ 231,133
Federated National Reinsurance Programs | Florida
Liability for Catastrophe Claims [Line Items]
Current year			$ 18,400	$ 13,500	$ 2,200
Quota Share Treaties | Property Insurance Product Line | Florida
Liability for Catastrophe Claims [Line Items]
Percentage of quota share reinsurance treaty	10.00%	30.00%