LOSS AND LOSS ADJUSTMENT RESERVES (Activity in Liability for Loss and LAE Reserves) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves, beginning-of-period	$ 324,362	$ 296,230
Less: reinsurance recoverable	(164,429)	(166,396)
Net reserves, beginning-of-period	159,933	129,834
Incurred loss, net of reinsurance, related to:
Current year	291,741	195,024
Prior year loss development	6,912	1,238
Ceded losses subject to offsetting experience account adjustments	(744)	(1,978)
Prior years	6,168	(740)
Amortization of acquisition fair value adjustment	(47)	0
Total incurred loss and LAE, net of reinsurance	297,862	194,284
Paid loss, net of reinsurance, related to:
Current year	143,106	114,790
Prior years	109,930	77,398
Total paid loss and LAE, net of reinsurance	253,036	192,188
Net reserves, end-of-period	204,759	131,930
Plus: reinsurance recoverable	349,221	155,018
Gross reserves, end-of-period	$ 553,980	$ 286,948