ACQUISITIONS AND DISPOSITIONS - Disposals (Details) $ in Thousands		3 Months Ended
	Mar. 28, 2017 USD ($) ft²	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Disposed Property Information
Sales Price		$ 0	$ 289,939
Gain on sale of real estate		$ 0	$ 187,734
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Disposals
Ownership sold, percentage			100.00%
Assets
Investments in real estate, net			$ 93,747
Deferred rent receivable and charges, net			10,822
Other intangible assets, net			32
Total assets			104,601
Liabilities
Debt, net			25,996
Intangible liabilities, net			1,731
Total liabilities			27,727
Additional Information
Premium on assumed mortgage			$ 665
211 Main Street, San Francisco | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Disposed Property Information
Square Feet | ft²	417,266
Sales Price	$ 292,882
Transaction Costs	2,943
Gain on sale of real estate	187,734
Mortgage prepayment penalty	$ 1,508