FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Financial Assets [Abstract]
Cash and Cash Equivalents, at Carrying Value		$ 257	$ 16	$ 10	$ 522
Fair Value [Member]
Financial Assets [Abstract]
Cash and Cash Equivalents, Fair Value Disclosure		257	16
Mortgage loans receivable		2,531	4,569
Interest rate swap assets		10,693	6,034
Financial Liabilities [Abstract]
Unsecured bank credit facilities - variable rate	[1]	171,571	116,277
Unsecured bank credit facilities - fixed rate	[1]	0	80,003
Unsecured debt Fair Value Disclosure	[1]	700,706	703,871
Secured debt	[1]	193,304	206,408
Interest rate swap liabilities		0	695
Carrying Amount [Member]
Financial Assets [Abstract]
Cash and Cash Equivalents, at Carrying Value	[2]	257	16
Mortgage loans receivable	[2]	2,604	4,581
Interest rate swap assets	[2]	10,693	6,034
Financial Liabilities [Abstract]
Unsecured bank credit facilities - variable rate	[1],[2]	171,191	116,339
Unsecured bank credit facilities - fixed rate	[1],[2]	0	80,000
Unsecured debt Fair Value Disclosure	[1],[2]	725,000	715,000
Secured debt	[1],[2]	191,923	200,354
Interest rate swap liabilities	[2]	$ 0	$ 695

[1] Carrying amounts and fair values shown in the table exclude debt issuance costs (see Note 9 for additional information).

[2] Carrying amounts shown in the table are included on the Consolidated Balance Sheets under the indicated captions, except as explained in the notes below.(2) Carrying amounts and fair values shown in the table exclude debt issuance costs (see Note 9 for additional information).The following methods and assumptions were used to estimate the fair value of each class of financial instruments:Cash and cash equivalents: The carrying amounts approximate fair value due to the short maturity of those instruments.Mortgage loans receivable (included in Other assets on the Consolidated Balance Sheets): The fair value is estimated by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities (Level 2 input).Interest rate swap assets (included in Other assets on the Consolidated Balance Sheets): The instruments are recorded at fair value based on models using inputs, such as interest rate yield curves, LIBOR swap curves and OIS curves, observable for substantially the full term of the contract (Level 2 input). See Note 13 for additional information on the Company's interest rate swaps.Unsecured bank credit facilities: The fair value of the Company’s unsecured bank credit facilities is estimated by discounting expected cash flows at current market rates (Level 2 input), excluding the effects of debt issuance costs.Unsecured debt: The fair value of the Company’s unsecured debt is estimated by discounting expected cash flows at the rates currently offered to the Company for debt of the same remaining maturities, as advised by the Company’s bankers (Level 2 input), excluding the effects of debt issuance costs.Secured debt: The fair value of the Company’s secured debt is estimated by discounting expected cash flows at the rates currently offered to the Company for debt of the same remaining maturities, as advised by the Company’s bankers (Level 2 input), excluding the effects of debt issuance costs.Interest rate swap liabilities (included in Other liabilities on the Consolidated Balance Sheets): The instruments are recorded at fair value based on models using inputs, such as interest rate yield curves, LIBOR swap curves and OIS curves, observable for substantially the full term of the contract (Level 2 input). See Note 13 for additional information on the Company's interest rate swaps.