LOSS AND LOSS ADJUSTMENT RESERVES - (Schedule of Activity in Liability for Loss and LAE Reserves) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserves, beginning-of-period	$ 296,230	$ 230,515	$ 158,110
Less: reinsurance recoverable	(166,396)	(98,345)	(40,412)
Net reserves, beginning-of-period	129,834	132,170	117,698
Net reserves from Maison acquisition	11,825	0	0
Incurred loss, net of reinsurance, related to:
Current year	262,118	231,133	245,545
Prior year loss development	13,460	2,166	13,926
Ceded losses under retrospectively rated quota-share	(2,489)	(4,883)	(11,914)
Prior years	10,971	(2,717)	2,012
Amortization of acquisition fair value adjustment	(9)	0	0
Total incurred loss and LAE, net of reinsurance	273,080	228,416	247,557
Paid loss, net of reinsurance, related to:
Current year	173,313	155,462	160,945
Prior years	81,493	75,290	72,140
Total paid loss and LAE, net of reinsurance	254,806	230,752	233,085
Net reserves, end-of-period	159,933	129,834	132,170
Plus: reinsurance recoverable	164,429	166,396	98,345
Gross reserves, end-of-period	$ 324,362	$ 296,230	$ 230,515