INVESTMENT OPERATIONS - Schedule of Other-than-Temporary Impairments of Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Investment [Line Items]
Other-than-temporary impairments	$ (1,295)	$ (691)
Net impairment losses recognized in earnings	(3,142)	(3,645)
Fixed maturities
Investment [Line Items]
Other-than-temporary impairments	(1,295)	(691)
Non-credit impairment losses recorded in other comprehensive income (loss)	(1,847)	(2,954)
Net impairment losses recognized in earnings	$ (3,142)	$ (3,645)