Real Estate Investments - Property Sales (Details)	3 Months Ended	6 Months Ended
	Mar. 31, 2020 USD ($) item property	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Disposals and other
Carrying value	$ 1,117,845,000	$ 1,117,845,000	$ 1,136,816,000
Net Gain (Loss)	$ 43,854,000
Properties sold
Disposals and other
Number of properties sold | property	21
Number of beds or units in property sold | item	2,411
Sales price	$ 74,800,000
Carrying value	29,084,000	29,084,000
Net Gain (Loss)	$ 43,854,000
Properties sold | SNF | Arizona
Disposals and other
Number of properties sold | property	1
Number of beds or units in property sold | item	194
Sales price	$ 12,550,000
Carrying value	2,229,000	2,229,000
Net Gain (Loss)	$ 10,293,000
Properties sold | SNF | Colorado
Disposals and other
Number of properties sold | property	3
Number of beds or units in property sold | item	275
Sales price	$ 15,000,000
Carrying value	4,271,000	4,271,000
Net Gain (Loss)	$ 10,365,000
Properties sold | SNF | Kansas
Disposals and other
Number of properties sold | property	3
Number of beds or units in property sold | item	250
Sales price	$ 9,750,000
Carrying value	7,438,000	7,438,000
Net Gain (Loss)	$ 1,994,000
Properties sold | SNF | Iowa
Disposals and other
Number of properties sold | property	7
Number of beds or units in property sold | item	544
Sales price	$ 14,500,000
Carrying value	4,886,000	4,886,000
Net Gain (Loss)	8,914,000
Holdback amount	838,000	838,000
Realizable holdback amount	$ 471,000
Properties sold | SNF | Texas
Disposals and other
Number of properties sold | property	7
Number of beds or units in property sold | item	1,148
Sales price	$ 23,000,000
Carrying value	10,260,000	10,260,000
Net Gain (Loss)	$ 12,288,000
Preferred Care, Inc.
Disposals and other
Number of properties sold | property	21
Number of beds or units in property sold | item	2,411
Net Gain (Loss)	$ 43,900,000	$ 44,000,000