INTANGIBLE ASSETS AND LIABILITIES - Summary of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Lease Intangible Assets:
Gross lease intangible assets	$ 180,215	$ 31,417
Accumulated amortization	(13,096)	(5,167)
Lease intangible assets, net	167,119	26,250
Lease Intangible Liabilities:
Below market leases	102,643	0
Accumulated amortization	(4,628)	0
Lease intangible liabilities, net	98,015	0
Above market leases
Lease Intangible Assets:
Gross lease intangible assets	76,443	0
Tenant origination and absorption costs
Lease Intangible Assets:
Gross lease intangible assets	76,336	23,987
Tenant relationship
Lease Intangible Assets:
Gross lease intangible assets	$ 27,436	$ 7,430