BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loans Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 11, 2014
Loans receivable
Impairment (recovery) on loans receivable	$ 97	$ (206)	$ 328
PMC Commercial
Loans receivable
Discount on acquisition				$ 33,907
Acquisition discounts	$ 1,301
Commercial mortgage loans
Loans receivable
Unamortized acquisition discounts			$ 15,951