LOSS AND LOSS ADJUSTMENT RESERVES (Narrative) (Details) - USD ($) $ in Thousands			1 Months Ended	9 Months Ended
	Feb. 28, 2021	Jul. 01, 2017	Jul. 31, 2016	Sep. 30, 2021	Sep. 30, 2020
Liability for Future Policy Benefit, by Product Segment [Line Items]
Claim and claim adjustment expenses incurred related to current year				$ 183,307	$ 291,741
Reinsurance Programs | Florida
Liability for Future Policy Benefit, by Product Segment [Line Items]
Claim and claim adjustment expenses incurred related to current year				$ 1,900	$ 6,900
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	30.00%	10.00%	30.00%
Settlement adjustment	$ 11,200