INVESTMENTS IN CONSUMER LOANS - Allowance for Loan Losses on Performing Consumer Loans, Held-for-Investment (Details) - Consumer Portfolio Segment - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Loans Receivable [Roll Forward]
UPB of Underlying Mortgages		$ 10,900
Post-modification recorded investment		9,400
Performing Loans
Loans Receivable [Roll Forward]
Collectively Evaluated, beginning balance	$ 0	2,441
Individually Impaired, beginning balance	0	997
Beginning balance	0	3,438
Provision (reversal) for loan losses	50,503	65,738
Provision for loan losses	(47,065)	(63,071)
Collectively Evaluated, ending balance	2,441	4,429	$ 2,441
Individually Impaired, ending balance	997	1,676	997
Ending balance	3,438	6,105	3,438
Recovery of bad debts		10,800	$ 8,100
Collectively Evaluated | Performing Loans
Loans Receivable [Roll Forward]
Provision (reversal) for loan losses	49,506	65,059
Provision for loan losses	(47,065)	(63,071)
Individually Impaired | Performing Loans
Loans Receivable [Roll Forward]
Provision (reversal) for loan losses	997	679
Provision for loan losses	$ 0	$ 0