SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investment in Unconsolidated Joint Venture (Details) $ in Thousands		6 Months Ended
	Jan. 02, 2018 USD ($) Property director	Jun. 30, 2019 USD ($) Property	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Investment in joint venture		$ 328,207	$ 340,120
Enlivant Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of properties | Property	172
Gross proceeds from sale of senior housing communities		$ 6,300
Enlivant Joint Venture | Senior Housing Communities
Schedule of Equity Method Investments [Line Items]
Number of senior housing communites sold | Property		2
Enlivant Joint Venture
Schedule of Equity Method Investments [Line Items]
Cash contributed to acquire equity interests	$ 352,700
Equity interest in joint venture	49.00%
Outstanding indebtedness	$ 791,300
Net working capital	$ 22,900
Number of directors appointed by Sabra | director	3
Number of directors on board | director	7
Aggregate net loss on sale of real estate		$ 1,700
Investment in joint venture		$ 328,200