DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Summary of the Notional Amount and Fair Value of Derivatives) (Details) - USD ($)		3 Months Ended	6 Months Ended
	Jan. 19, 2018	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	May 17, 2018	Dec. 31, 2017
Fair value of derivative instruments
Hedge ineffectiveness recorded in other income		$ 700,000	$ 700,000
Gain on unwinding of swaps			9,390,000	$ 0
Total fair value derivative assets		7,269,000	7,269,000			$ 4,470,000
Total fair value derivative liabilities		(694,000)	(694,000)			(5,961,000)
Repayments on mortgage loan			41,573,000	$ 1,085,438,000
Interest Rate Swap | Designated as Hedging Instrument
Fair value of derivative instruments
Notional		250,000,000.0	250,000,000.0		$ 250,000,000
Gain on unwinding of swaps		$ 9,400,000
Derivative change in fair value recognition period		9 years 6 months
Gain on derivative expected amount to be reclassified		$ 2,800,000	2,800,000
Interest Rate Swap | Designated as Hedging Instrument | Accounts payable and accrued expenses | Fixed Interest Rate 2.96%, Maturing October 2019
Fair value of derivative instruments
Notional		$ 18,926,000	$ 18,926,000
Fixed Interest Rate		2.96%	2.96%
Total fair value derivative liabilities		$ 0	$ 0			(286,000)
Interest Rate Swap | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 1.66%, Maturing May 2020
Fair value of derivative instruments
Notional		$ 40,000,000	$ 40,000,000
Fixed Interest Rate		1.66%	1.66%
Total fair value derivative assets		$ 664,000	$ 664,000			299,000
Interest Rate Swap | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 1.14%, Maturing September 2021
Fair value of derivative instruments
Notional		$ 119,359,000	$ 119,359,000
Fixed Interest Rate		1.14%	1.14%
Total fair value derivative assets		$ 5,747,000	$ 5,747,000			4,007,000
Interest Rate Swap | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.65%, Maturing December 2027
Fair value of derivative instruments
Notional		$ 50,000,000	$ 50,000,000
Fixed Interest Rate		2.65%	2.65%
Total fair value derivative liabilities		$ 0	$ 0			(1,124,000)
Interest Rate Swap | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.68%, Maturing December 2027
Fair value of derivative instruments
Notional		$ 100,000,000	$ 100,000,000
Fixed Interest Rate		2.68%	2.68%
Total fair value derivative liabilities		$ 0	$ 0			(2,509,000)
Interest Rate Swap | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.62%, Maturing December 2027
Fair value of derivative instruments
Notional		$ 100,000,000	$ 100,000,000
Fixed Interest Rate		2.62%	2.62%
Total fair value derivative liabilities		$ 0	$ 0			(2,042,000)
Interest Rate Cap | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate5.00 Maturing August2019
Fair value of derivative instruments
Notional		$ 75,000,000	$ 75,000,000
Fixed Interest Rate		5.00%	5.00%
Total fair value derivative assets		$ 0	$ 0			0
Interest Rate Cap | Not Designated as Hedging Instrument, Economic Hedge | Accounts payable and accrued expenses | Fixed Interest Rate 2.50%, Maturing December 2019
Fair value of derivative instruments
Interest (income) expense		200,000	500,000
Interest Rate Cap | Not Designated as Hedging Instrument, Economic Hedge | Prepaid expenses and other assets, net | Fixed Interest Rate 2.50%, Maturing December 2019
Fair value of derivative instruments
Notional		$ 230,000,000	$ 230,000,000
Fixed Interest Rate		2.50%	2.50%
Total fair value derivative assets		$ 684,000	$ 684,000			164,000
Interest Rate Collar | Designated as Hedging Instrument | Accounts payable and accrued expenses | Fixed Interest Rate 2.75% To 3.50%, Maturing April 2022
Fair value of derivative instruments
Notional		381,404,000	381,404,000
Total fair value derivative liabilities		(694,000)	(694,000)			0
Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 1.50% To 2.50%, Maturing May 2019
Fair value of derivative instruments
Notional		51,592,000	51,592,000
Total fair value derivative assets		24,000	24,000			0
Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.00% To 3.00%, Maturing May 2020
Fair value of derivative instruments
Notional		193,967,000	193,967,000
Total fair value derivative assets		62,000	62,000			0
Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.25% To 3.25%, Maturing May 2021
Fair value of derivative instruments
Notional		354,217,000	354,217,000
Total fair value derivative assets		$ 88,000	$ 88,000			$ 0
Wacker110 N
Fair value of derivative instruments
Total fair value derivative liabilities	$ (300,000)
Repayments on mortgage loan	$ 18,900,000
Minimum | Interest Rate Swap | Designated as Hedging Instrument | Accounts payable and accrued expenses | Fixed Interest Rate 2.75% To 3.50%, Maturing April 2022
Fair value of derivative instruments
Fixed Interest Rate		2.75%	2.75%
Minimum | Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 1.50% To 2.50%, Maturing May 2019
Fair value of derivative instruments
Fixed Interest Rate		1.50%	1.50%
Minimum | Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.00% To 3.00%, Maturing May 2020
Fair value of derivative instruments
Fixed Interest Rate		2.00%	2.00%
Minimum | Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.25% To 3.25%, Maturing May 2021
Fair value of derivative instruments
Fixed Interest Rate		2.25%	2.25%
Maximum | Interest Rate Swap | Designated as Hedging Instrument | Accounts payable and accrued expenses | Fixed Interest Rate 2.75% To 3.50%, Maturing April 2022
Fair value of derivative instruments
Fixed Interest Rate		3.50%	3.50%
Maximum | Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 1.50% To 2.50%, Maturing May 2019
Fair value of derivative instruments
Fixed Interest Rate		2.50%	2.50%
Maximum | Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.00% To 3.00%, Maturing May 2020
Fair value of derivative instruments
Fixed Interest Rate		3.00%	3.00%
Maximum | Interest Rate Collar | Designated as Hedging Instrument | Prepaid expenses and other assets, net | Fixed Interest Rate 2.25% To 3.25%, Maturing May 2021
Fair value of derivative instruments
Fixed Interest Rate		3.25%	3.25%