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		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income statement-related [Abstract]
Amount of gain (loss) reclassified from Accumulated other comprehensive income		$ (36,390)	$ (4,808)	$ 19,955
Other comprehensive income (loss)-related [Abstract]
Amount of gain (loss) recognized in Other comprehensive income		25,716	21,531	(1,370)
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		36,390	4,448	(21,191)
Interest Expense [Member] | Secured Borrowings [Member]
Income statement-related [Abstract]
Amount of gain (loss) reclassified from Accumulated other comprehensive income		38,292	7,686	(17,180)
Amount of loss recognized in income			(360)	(1,236)
Decrease (increase) in interest expense and increase(decrease) in Net income as a result of the use of Derivatives	[1]	38,292	7,326	(18,416)
Interest Expense [Member] | Unsecured Borrowings [Member]
Income statement-related [Abstract]
Amount of gain (loss) reclassified from Accumulated other comprehensive income	[2]	$ (1,902)	$ (2,878)	$ (2,775)

[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