RESERVES FOR LOSSES AND LOSS SETTLEMENT EXPENSES (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 liability for losses and loss settlement expenses at beginning of year	$ 1,312,483	$ 1,224,183	$ 1,123,896
Ceded losses and loss settlement expenses	(57,094)	(59,871)	(59,794)
Net liability for losses and loss settlement expenses at beginning of year	1,255,389	1,164,312	1,064,102
Losses and loss settlement expenses incurred for claims occurring during
Current year	835,507	785,778	779,966
Prior years	(5,335)	(54,167)	(54,253)
Total incurred	830,172	731,611	725,713
Losses and loss settlement expense payments for claims occurring during
Current year	333,975	306,032	311,972
Prior years	398,368	334,502	313,531
Total paid	732,343	640,534	625,503
Net liability for losses and loss settlement expenses at end of year	1,353,218	1,255,389	1,164,312
Ceded loss and loss settlement expenses	68,536	57,094	59,871
Gross liability for losses and loss settlement expenses at end of year	$ 1,421,754	$ 1,312,483	$ 1,224,183