DISPOSITIONS - Real Estate Assets Classified As Held For Sale (Details) $ in Thousands	Sep. 30, 2016 USD ($) property	Dec. 31, 2015 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	32	11
Assets held for sale	$ 195,252	$ 93,060
Liabilities related to assets held for sale	$ 77,608	$ 34,340
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	25	2
Assets held for sale	$ 140,948	$ 4,488
Liabilities related to assets held for sale	$ 76,092	$ 44
Office Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	7	8
Assets held for sale	$ 52,487	$ 68,619
Liabilities related to assets held for sale	$ 1,507	$ 24,759
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	1
Assets held for sale	$ 1,817	$ 19,953
Liabilities related to assets held for sale	$ 9	$ 9,537
Vacant Land Parcel | 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