DEBT AND OTHER OBLIGATIONS - Non-Recourse Funding Obligations Outstanding (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Outstanding Principal	$ 2,574,691	$ 2,693,691
Carrying Value	2,632,497	2,747,477
Golden Gate Captive Insurance Company
Debt Instrument [Line Items]
Outstanding Principal	1,883,000	2,014,000
Carrying Value	$ 1,883,000	$ 2,014,000
Year-to-Date Weighted-Avg Interest Rate	4.75%	4.75%
Golden Gate II
Debt Instrument [Line Items]
Outstanding Principal	$ 20,600	$ 58,600
Carrying Value	$ 17,703	$ 49,787
Year-to-Date Weighted-Avg Interest Rate	4.99%	3.88%
Golden Gate V
Debt Instrument [Line Items]
Outstanding Principal	$ 670,000	$ 620,000
Carrying Value	$ 729,454	$ 681,285
Year-to-Date Weighted-Avg Interest Rate	5.12%	5.12%
MONY
Debt Instrument [Line Items]
Outstanding Principal	$ 1,091	$ 1,091
Carrying Value	$ 2,340	$ 2,405
Year-to-Date Weighted-Avg Interest Rate	6.19%	6.19%