SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands		12 Months Ended
	Oct. 17, 2014	Dec. 31, 2016 USD ($) risk	Dec. 31, 2015 USD ($)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Reverse stock split	0.5
Number of significant types of economic risk | risk		2
Monthly payment threshold period to determine whether loan is past due (in days)		30 days
Principal or interest past due threshold period (in days)		120 days
Restricted cash		$ 163,095	$ 94,702
General maturity term of repurchase agreements and notes payable (in years)		1 year
Secured Corporate Note [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Restricted cash		$ 22,300	900
Servicer Advances [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Restricted cash		$ 82,100	$ 93,800