INVESTMENT OPERATIONS - Schedule of Fair Value (Proceeds) and Gains/Losses Realized on Securities Sold in an Unrealized Gain/Loss Position (Details) - USD ($) $ in Thousands	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2014
Successor
Investment [Line Items]
Fair value (proceeds)		$ 950,874	$ 1,198,333
Gains realized		8,745	42,085
Fair value (proceeds)		178,415	85,835
Losses realized		$ (8,463)	$ (9,783)
Predecessor
Investment [Line Items]
Fair value (proceeds)	$ 172,551			$ 1,661,162
Gains realized	6,920			78,119
Fair value (proceeds)	435			22,868
Losses realized	$ (29)			$ (1,168)