LOSS AND LOSS ADJUSTMENT RESERVES (Activity in Liability for Loss and LAE Reserves) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves, beginning-of-period	$ 540,367	$ 324,362
Less: reinsurance recoverable	(406,949)	(183,031)	$ (358,128)	$ (164,429)
Net reserves, beginning-of-period	182,239	159,933
Incurred loss, net of reinsurance, related to:
Current year	124,303	192,109
Prior year loss development (redundancy)	1,220	7,340
Ceded losses subject to offsetting experience account adjustments	(68)	(528)
Prior years	1,152	6,812
Amortization of acquisition fair value adjustment	(9)	(75)
Total incurred loss and LAE, net of reinsurance	125,446	198,846
Paid loss, net of reinsurance, related to:
Current year	43,235	75,612
Prior years	87,985	78,475
Total paid loss and LAE, net of reinsurance	131,220	154,087
Net reserves, end-of-period	176,465	204,692
Plus: reinsurance recoverable	406,949	183,031	$ 358,128	$ 164,429
Gross reserves, end-of-period	$ 583,414	$ 387,723