INVESTMENT OPERATIONS - Schedule of Available-for-Sale Credit Losses on Fixed Maturities Held by the Company for Which a Portion of Other-than-Temporary Impairments were Recognized in Other Comprehensive Income (Details) - Fixed maturities - USD ($) $ in Thousands	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Credit losses on fixed maturities
Beginning balance		$ 0	$ 12,685	$ 22,761
Additions for newly impaired securities		22,761	734	14,876
Additions for previously impaired securities		0	3,175	2,063
Reductions for previously impaired securities due to a change in expected cash flows		0	(12,726)	(24,396)
Reductions for previously impaired securities that were sold in the current period		0	(600)	(2,619)
Other		0	0	0
Ending balance	$ 0	22,761	$ 3,268	$ 12,685
Predecessor
Credit losses on fixed maturities
Beginning balance	15,478	$ 15,699
Additions for newly impaired securities	0
Additions for previously impaired securities	221
Reductions for previously impaired securities due to a change in expected cash flows	0
Reductions for previously impaired securities that were sold in the current period	0
Other	0
Ending balance	$ 15,699