Real Estate Investments - Operator changes (Details)		1 Months Ended	3 Months Ended			6 Months Ended			12 Months Ended
	Oct. 04, 2019 USD ($)	Jul. 31, 2020 USD ($) lease item	Jun. 30, 2020 USD ($) property	Mar. 31, 2020 USD ($) property item	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) property	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2017 item	Dec. 31, 2019 USD ($)
Other disclosures
Rental income			$ 20,275,000		$ 38,277,000	$ 58,310,000		$ 75,901,000
Proceeds from sale of real estate, net						72,141,000		231,000
Gain on sale of real estate, net			189,000		$ 500,000	$ 44,043,000		$ 500,000
Net book value											$ 26,856,000
Anthem Memory Care
Other disclosures
Number of properties in default | property						11
Anthem Memory Care | Forecast
Other disclosures
Minimum cash rent received									$ 9,900,000
Preferred Care, Inc.
Other disclosures
Number of properties under two master leases | item										24
Number of master leases | item										2
Number of properties sold | property				21
Number of beds or units in property sold | item				2,411
Proceeds from sale of real estate, net				$ 72,100,000			$ 77,900,000
Gain on sale of real estate, net				44,043,000			44,000,000
Net book value				$ 29,100,000			$ 29,100,000				$ 35,600,000
Senior Lifestyle Corporation
Other disclosures
Number of properties in default | property						23
Contractual rent		$ 1,520,000	4,560,000
Remaining outstanding accounts receivable			2,755,000			$ 2,755,000
Rent receivable line of credit and security deposit as collateral			3,608,000			$ 3,608,000
Write-off of rent receivable and lease incentives		17,742,000
Rental income		$ 1,081,000	$ 1,805,000
Brookdale Senior Living | Subsequent Event
Other disclosures
Number of leases consolidated | lease		4
Number of renewal option | item		3
Renewal term option one		4 years
Renewal term option two		5 years
Renewal term option three		10 years
Senior Care Centers
Other disclosures
Court ordered payment amount	$ 1,596,000
Real Estate Investment
Other disclosures
Number of properties | property			158			158
Real Estate Investment | Maximum
Other disclosures
Initial lease term			15 years			15 years