LOSS AND LOSS ADJUSTMENT RESERVES - (Schedule of Activity in Liability for Loss and LAE Reserves) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gross reserves, beginning of period	$ 158,110	$ 97,706	$ 78,330
Less: reinsurance recoverable	40,412	7,496	10,394
Net reserves, beginning of period	117,698	90,210	67,936
Incurred loss, net of reinsurance, related to:
Current year	245,545	201,704	120,005
Prior year loss development	13,926	13,156	(9,466)
Ceded losses under retrospectively rated quota-share	(11,914)	(17,050)	2,171
Prior years	2,012	(3,894)	(7,295)
Total incurred loss and LAE, net of reinsurance	247,557	197,810	112,710
Paid loss, net of reinsurance, related to:
Current year	160,945	123,364	54,710
Prior years	72,140	46,958	35,726
Total paid loss and LAE, net of reinsurance	233,085	170,322	90,436
Net reserves, end of period	132,170	117,698	90,210
Plus: reinsurance recoverable	98,345	40,412	7,496
Gross reserves, end of period	230,515	$ 158,110	$ 97,706
Homeowners [Member]
Paid loss, net of reinsurance, related to:
Gross reserves, end of period	99,650
Personal Auto Liability [Member]
Paid loss, net of reinsurance, related to:
Gross reserves, end of period	11,030
Commercial General Liability [Member]
Paid loss, net of reinsurance, related to:
Gross reserves, end of period	$ 17,111