INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended			0 Months Ended					3 Months Ended	9 Months Ended
	Sep. 30, 2014 Tenants sqft	Sep. 30, 2013	Sep. 30, 2014 Tenants sqft	Sep. 30, 2013	Dec. 31, 2013	Dec. 23, 2013 110 William Street [Member]	Dec. 23, 2013 110 William Street [Member] First Mortgage [Member]	Dec. 23, 2013 110 William Street [Member] Mezzanine Loan [Member]	May 18, 2012 NIP Joint Venture [Member] sqft	Sep. 30, 2014 NIP Joint Venture [Member] property	Dec. 31, 2013 NIP Joint Venture [Member]	May 18, 2012 NIP Joint Venture [Member] Maximum [Member]	May 18, 2012 NIP Joint Venture [Member] Industrial [Member] property	Sep. 30, 2014 110 William Joint Venture [Member] property	Sep. 30, 2014 110 William Joint Venture [Member] property	Dec. 31, 2013 110 William Joint Venture [Member]	Dec. 23, 2013 110 William Joint Venture [Member] sqft	Dec. 23, 2013 110 William Joint Venture [Member] 110 William JV Partner [Member] Tenants
Schedule of Equity Method Investments [Line Items]
Number of real estate properties										23			23	1	1
Rentable square feet	4,600,000		4,600,000						11,400,000								928,157
Initial capital contribution			$ 58,387,000	$ 0					$ 8,000,000
Ownership interest												5.00%		60.00%	60.00%			60.00%
Investments in unconsolidated joint ventures	73,968,000		73,968,000		16,338,000					7,484,000	7,484,000			66,484,000	66,484,000	8,854,000
Area of land																	0.8
Percent of property leased																		97.00%
Number of tenants	450		450															33
Noncontrolling interest																		40.00%
Purchase price						261,100,000
Face amount of debt	520,781,000		520,781,000		255,871,000		141,500,000	20,000,000
Contractual interest rate, percentage							4.80%	9.50%
Equity in loss of unconsolidated joint venture	$ (256,000)	$ 0	$ (757,000)	$ 0										$ (256,000)	$ (757,000)