MORTGAGE LOAN RECEIVABLES - Provision for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Provision for loan losses at beginning of period	$ 3,700	$ 3,100	$ 2,500
Provision for loan losses	300	600	600
Provision for loan losses at end of period	$ 4,000	$ 3,700	$ 3,100