USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Components of Income Statement and Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Income statement-related [Abstract]
Amount of gain (loss) reclassified from Accumulated other comprehensive income		$ (4,644)	$ 1,661
Other comprehensive income (loss)-related [Abstract]
Amount of gain recognized in Other comprehensive income		30,933	8,096
Interest Expense [Member]
Income statement-related [Abstract]
Decrease (increase) in interest expense and increase(decrease) in Net income as a result of the use of Derivatives		4,644	(2,054)
Interest Expense [Member] | Secured Borrowings [Member]
Income statement-related [Abstract]
Amount of gain (loss) reclassified from Accumulated other comprehensive income		5,247	(888)
Amount of loss recognized in income			(393)
Decrease (increase) in interest expense and increase(decrease) in Net income as a result of the use of Derivatives	[1]	5,247	(1,281)
Interest Expense [Member] | Unsecured Borrowings [Member]
Income statement-related [Abstract]
Amount of gain (loss) reclassified from Accumulated other comprehensive income	[2]	$ (603)	$ (773)

[1] Included in “Interest expense: Secured borrowings” on the face of the Statements of Income.

[2] Included in “Interest expense: Unsecured borrowings” on the face of the Statements of Income