INVESTMENT OPERATIONS - Summary of Change in Unrealized Gains (Losses), Net of Income Tax, on Fixed Maturity and Equity Securities, Classified as Available-for-Sale (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		8 Months Ended	9 Months Ended
	Jan. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2016
Successor | Fixed maturities
Investment Holdings [Line Items]
Change in unrealized gains (losses), net of income tax		$ 295,651	$ (54,282)	$ (1,437,623)	$ 1,777,330
Successor | Equity securities
Investment Holdings [Line Items]
Change in unrealized gains (losses), net of income tax		$ (1,691)	$ 2,385	$ (5,152)	$ 7,749
Predecessor | Fixed maturities
Investment Holdings [Line Items]
Change in unrealized gains (losses), net of income tax	$ 670,229
Predecessor | Equity securities
Investment Holdings [Line Items]
Change in unrealized gains (losses), net of income tax	$ 10,226