REINSURANCE - (Premiums Written and Earned) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Premiums Written, Net [Abstract]
Direct									$ 567,764	$ 603,417	$ 605,485
Ceded									(202,732)	(260,524)	(285,986)
Net premiums written									365,032	342,893	319,499
Premiums Earned, Net [Abstract]
Direct									580,020	603,193	565,423
Ceded									(224,763)	(269,712)	(304,054)
Premiums Earned, Net, Property and Casualty	$ 91,098	$ 98,493	$ 83,557	$ 82,109	$ 87,503	$ 80,764	$ 83,554	$ 81,660	$ 355,257	$ 333,481	$ 261,369