INVESTMENTS (Net Realized Gains (Losses) by Major Investment Category (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gross realized gains and losses [Abstract]
Total gross realized gains	$ 7,145	$ 1,494	$ 11,247	$ 4,574
Total gross realized losses	(1,044)	(368)	(2,603)	(2,514)
Net realized gains on investments	6,101	1,126	8,644	2,060
Debt Securities [Member]
Gross realized gains and losses [Abstract]
Total gross realized gains	618	897	1,471	2,822
Total gross realized losses	(103)	(20)	(1,293)	(614)
Equity Securities [Member]
Gross realized gains and losses [Abstract]
Total gross realized gains	6,527	597	9,776	1,752
Total gross realized losses	$ (941)	$ (348)	$ (1,310)	$ (1,900)