REAL ESTATE PROPERTIES HELD FOR INVESTMENT - Operating Leases (Details)		4 Months Ended	9 Months Ended
	Aug. 27, 2018 USD ($) Facilitiy	Sep. 30, 2018 USD ($) Facilitiy	Sep. 30, 2018 USD ($) Facilitiy	Sep. 30, 2017 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Real Estate Properties [Line Items]
Security deposit liability		$ 14,300,000	$ 14,300,000			$ 20,300,000
Letters of credit deposited		89,000,000	89,000,000			96,000,000
Tenant deposits for future real estate taxes, insurance expenditures, and tenant improvements		20,900,000	20,900,000			28,300,000
Reserve for unpaid cash rents		1,200,000	1,200,000			3,200,000
Reserve for accumulated straight-line rental income		$ 7,900,000	7,900,000			$ 12,400,000
Straight-line rent recorded			$ 34,404,000	$ 18,260,000
Genesis
Real Estate Properties [Line Items]
Number of properties | Facilitiy		26	26
Reduction of annual base rent payable under operating leases					$ 19,000,000
Number of facilities expected to be sold | Facilitiy		18	18
Number of facilities expected to be retained | Facilitiy		8	8
Senior Care Centers
Real Estate Properties [Line Items]
Aggregate sale price of facility	$ 405,000,000
Potential earnout opportunity	27,500,000
Shortfall in cash rents			$ 1,900,000
Straight-line rent recorded		$ 0
Annual lease rent prior to termination	$ 58,500,000
Minimum
Real Estate Properties [Line Items]
Lease expiration period			1 year
Maximum
Real Estate Properties [Line Items]
Lease expiration period			15 years
Weighted Average
Real Estate Properties [Line Items]
Weighted average lease expiration period			9 years
Disposed of by Sale | Genesis
Real Estate Properties [Line Items]
Number of facilities sold | Facilitiy			28
Skilled Nursing Transitional Care Facilities | Senior Care Centers
Real Estate Properties [Line Items]
Number of facilities expected to be sold | Facilitiy	36
Senior Housing Facilities | Senior Care Centers
Real Estate Properties [Line Items]
Number of facilities expected to be sold | Facilitiy	2
Senior Housing - Managed Communities | Operating Segments
Real Estate Properties [Line Items]
Number of properties | Facilitiy		24	24