USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Components of Balance Sheet and Income Statement Location (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Balance sheet-related [Abstract]
Swap agreements in a gain position (an asset) related to borrowings		$ 2,470		$ 2,470		$ 24,709
Swap agreements in a loss position (a liability) related to borrowings		(24,787)		(24,787)		(24,417)
Interest rate swap agreements at fair value, net assets (liability)		(22,833)		(22,833)		(11,697)
Income statement-related [Abstract]
Amount of loss reclassified from Accumulated other comprehensive income related to the effective portion of active positions		(655)	$ 5,826	1,006	$ 11,180
Other comprehensive income (loss)-related [Abstract]
Amount of gain (loss) recognized in Other comprehensive income (loss) (effective portion)		(6,487)	(22,145)	1,609	(54,272)
Interest Expense [Member]
Income statement-related [Abstract]
Amount of loss reclassified from Accumulated other comprehensive income related to the effective portion of active positions		655	(5,826)	(1,006)	(11,180)
Amount of loss recognized (ineffective portion)		(1,108)	(239)	(1,501)	(887)
Increase in interest expense and decrease in Net income as a result of the use of Derivatives	[1]	(453)	$ (6,065)	(2,507)	$ (12,067)
Receivable and Other Assets [Member] | Interest Rate Swap Agreements [Member] | Secured Borrowings [Member]
Balance sheet-related [Abstract]
Swap agreements in a gain position (an asset) related to borrowings	[2]	2,470		2,470		24,709
Interest Rate Swap Agreements at Fair Value [Member] | Secured Borrowings [Member]
Balance sheet-related [Abstract]
Swap agreements in a loss position (a liability) related to borrowings	[2]					(222)
Interest Rate Swap Agreements at Fair Value [Member] | Unsecured Borrowings [Member]
Balance sheet-related [Abstract]
Swap agreements in a loss position (a liability) related to borrowings	[2]	(24,787)		(24,787)		(24,195)
Accounts Payable and Accrued Liabilities [Member]
Balance sheet-related [Abstract]
Related net interest payable	[3]	$ (516)		$ (516)		$ (11,989)

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

[2] The fair value of Derivatives with unrealized gains are aggregated and recorded as an asset on the face of the Balance Sheets separately from the fair value of Derivatives with unrealized losses that are recorded as a liability. The amount of net unrealized gains, net of unrealized losses, scheduled to be recognized in the Statements of Income over the next twelve months primarily in the form of current market rates in excess of fixed-rate swap payments totaled $14.6 million at June 30, 2017.

[3] Included in “Accounts payable and accrued expenses” on the face of the Balance Sheets.