DERIVATIVE INSTRUMENTS - Schedule of Realized Gains (Losses) on Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Unrealized Gain/(Loss)	$ (9,630)	$ (11,395)
Realized Gain/(Loss)	(41,232)	(27,744)
Net Result from Derivative Transactions	(50,862)	(39,139)
Caps
Derivative [Line Items]
Unrealized Gain/(Loss)		0
Realized Gain/(Loss)		0
Net Result from Derivative Transactions		0
Futures
Derivative [Line Items]
Unrealized Gain/(Loss)	(8,564)	(10,969)
Realized Gain/(Loss)	(40,797)	(27,038)
Net Result from Derivative Transactions	(49,361)	(38,007)
3MO LIBOR
Derivative [Line Items]
Unrealized Gain/(Loss)	(1,078)	(372)
Realized Gain/(Loss)	(338)	(610)
Net Result from Derivative Transactions	(1,416)	(982)
Credit Derivatives
Derivative [Line Items]
Unrealized Gain/(Loss)	12	(54)
Realized Gain/(Loss)	(97)	(96)
Net Result from Derivative Transactions	$ (85)	$ (150)