DISPOSITIONS - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) property parcel	Jun. 30, 2017 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Vacant parcels sold | parcel	2
Proceeds from sale of real estate | $	$ 307.1
Net gain on the sale of assets, net of tax | $	35.9
Impairment of real estate | $	$ 10.7	$ 15.6
Medical Office Buildings
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Number of real estate properties sold | property	9
Senior Living Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Number of real estate properties sold | property	6
Triple-Net Leased Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Number of real estate properties sold | property	5