DISPOSITIONS - Real Estate Assets Classified As Held For Sale (Details) $ in Thousands	Sep. 30, 2015 USD ($) property	Dec. 31, 2014 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	18	367
Assets held for sale	$ 168,931	$ 2,574,174
Liabilities related to assets held for sale	$ 65,465	$ 254,680
Number of Properties Classified as Held-for-sale, Contributed in Spin-Off | property		323
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	8	333
Assets held for sale	$ 80,178	$ 2,410,840
Liabilities related to assets held for sale	$ 12,265	$ 205,931
MOB Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	10	34
Assets held for sale	$ 88,753	$ 163,334
Liabilities related to assets held for sale	$ 53,200	$ 48,749
MOB Operations | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	2