DISPOSITIONS - Real Estate Assets Held For Sale (Details) $ in Thousands	Mar. 31, 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	3	1
Assets held for sale	$ 5,978	$ 5,454
Liabilities related to assets held for sale	$ 947	$ 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	1	1
Assets held for sale	$ 3,293	$ 5,482
Liabilities related to assets held for sale	$ 235	$ 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	2	0
Assets held for sale	$ 2,518	$ 160
Liabilities related to assets held for sale	$ 704	$ 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	0	0
Assets held for sale	$ 167	$ (188)
Liabilities related to assets held for sale	$ 8	$ 13