INVESTMENTS - (Net Realized Gains (Losses) by Major Investment Category (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gross realized and unrealized gains:
Total gross realized and unrealized gains	$ 8,757	$ 2,797	$ 11,758
Total gross realized and unrealized losses	(1,673)	(6,941)	(3,210)
Net realized and unrealized gains (losses) on investments	7,084	(4,144)	8,548
Debt Securities [Member]
Gross realized and unrealized gains:
Total gross realized and unrealized gains	2,829	423	1,814
Total gross realized and unrealized losses	(664)	(3,990)	(1,671)
Equity Securities [Member]
Gross realized and unrealized gains:
Total gross realized and unrealized gains	5,928	2,374	9,944
Total gross realized and unrealized losses	$ (1,009)	$ (2,951)	$ (1,539)