DERIVATIVE INSTRUMENTS (Summary of Derivative Activity) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains of derivative instruments	$ (1,442)	$ 2,309
Total return swaps
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains of derivative instruments	(4)	546
Net proceeds from derivative instrument	200	600
Basis swaps
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains of derivative instruments	(73)	192
Interest rate caps
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains of derivative instruments	(477)	396
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains of derivative instruments	(881)	1,416
Net proceeds from derivative instrument	100
Net payments for derivative instrument		100
Foreign currency forward exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains of derivative instruments	$ (7)	$ (241)