DEBT AND OTHER OBLIGATIONS - Non-Recourse Funding Obligations (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Outstanding Principal	$ 2,939,834	$ 3,079,834
Carrying Value	2,942,126	3,082,753
Golden Gate Captive Insurance Company
Debt Instrument [Line Items]
Outstanding Principal	1,858,000	2,028,000
Carrying Value	$ 1,858,000	$ 2,028,000
Year-to-Date Weighted-Avg Interest Rate	4.70%	4.70%
Golden Gate II Captive Insurance Company
Debt Instrument [Line Items]
Outstanding Principal	$ 329,949	$ 329,949
Carrying Value	$ 275,895	$ 274,955
Year-to-Date Weighted-Avg Interest Rate	3.91%	5.06%
Golden Gate V Vermont Captive Insurance Company
Debt Instrument [Line Items]
Outstanding Principal	$ 750,000	$ 720,000
Carrying Value	$ 806,015	$ 777,527
Year-to-Date Weighted-Avg Interest Rate	5.12%	5.12%
MONY Life Insurance Company
Debt Instrument [Line Items]
Outstanding Principal	$ 1,885	$ 1,885
Carrying Value	$ 2,216	$ 2,271
Year-to-Date Weighted-Avg Interest Rate	6.19%	6.19%