Real Estate Investments - Operator changes (Details)		3 Months Ended			6 Months Ended	12 Months Ended
	Oct. 04, 2019 USD ($)	Mar. 31, 2020 USD ($) property item	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 USD ($) property	Dec. 31, 2020 USD ($)	Dec. 31, 2017 item	Dec. 31, 2019 USD ($)
Other disclosures
Rental income		$ 38,035,000		$ 37,624,000
Proceeds from sale of real estate, net		71,905,000		$ 225,000
Gain on sale of real estate, net		43,854,000
Net book value								$ 26,856,000
Rent in year two		127,050,000			$ 127,050,000
Rent in year three		128,250,000			128,250,000
Rent in year four		$ 129,900,000			129,900,000
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
Minimum cash rent received			$ 55,000
Number of properties under two master leases | item							24
Number of master leases | item							2
Number of properties sold | property		21
Minimum cash rent receivable			$ 1,000,000
Number of beds or units in property sold | item		2,411
Proceeds from sale of real estate, net		$ 71,900,000			77,900,000
Gain on sale of real estate, net		43,900,000			44,000,000
Net book value		$ 29,100,000			$ 29,100,000			$ 35,600,000
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