DEBT AND OTHER OBLIGATIONS - Non-Recourse Funding Obligations Outstanding (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Outstanding Principal	$ 2,693,691	$ 2,740,691
Carrying Value	2,747,477	2,796,474
Golden Gate Captive Insurance Company
Debt Instrument [Line Items]
Outstanding Principal	2,014,000	2,116,000
Carrying Value	$ 2,014,000	$ 2,116,000
Year-to-Date Weighted-Avg Interest Rate	4.75%	4.75%
Golden Gate II
Debt Instrument [Line Items]
Outstanding Principal	$ 58,600	$ 58,600
Carrying Value	$ 49,787	$ 49,983
Year-to-Date Weighted-Avg Interest Rate	3.88%	2.52%
Golden Gate V
Debt Instrument [Line Items]
Outstanding Principal	$ 620,000	$ 565,000
Carrying Value	$ 681,285	$ 628,025
Year-to-Date Weighted-Avg Interest Rate	5.12%	5.12%
MONY
Debt Instrument [Line Items]
Outstanding Principal	$ 1,091	$ 1,091
Carrying Value	$ 2,405	$ 2,466
Year-to-Date Weighted-Avg Interest Rate	6.19%	6.19%