DISPOSITIONS - Real Estate Assets Held For Sale (Details) $ in Thousands	Jun. 30, 2019 USD ($) property	Dec. 31, 2018 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties held for sale | property	1	1
Assets held for sale	$ 1,754	$ 5,454
Liabilities related to assets held for sale	$ 1,216	$ 205
Triple-Net Leased Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties held for sale | property	0	1
Assets held for sale	$ 0	$ 5,482
Liabilities related to assets held for sale	$ 12	$ 40
Office Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties held for sale | property	0	0
Assets held for sale	$ 37	$ 160
Liabilities related to assets held for sale	$ 927	$ 152
Senior Living Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties held for sale | property	1	0
Assets held for sale	$ 1,717	$ (188)
Liabilities related to assets held for sale	$ 277	$ 13