LOSS AND LOSS ADJUSTMENT RESERVES (Narrative) (Details) - USD ($) $ in Thousands		1 Months Ended	9 Months Ended
	Jul. 01, 2017	Jul. 31, 2016	Sep. 30, 2020	Sep. 30, 2019
Liability for Future Policy Benefit, by Product Segment [Line Items]
Claim and claim adjustment expenses incurred related to current year			$ (291,741)	$ (195,024)
Reinsurance Programs | Florida
Liability for Future Policy Benefit, by Product Segment [Line Items]
Claim and claim adjustment expenses incurred related to current year			$ (6,900)	$ 1,200
Quota Share Treaties | Florida | Property Insurance Product Line
Liability for Future Policy Benefit, by Product Segment [Line Items]
Percentage of property quota share reinsurance treaty	10.00%	30.00%