Dispositions of Real Estate and Discontinued Operations - Held for Sale and Discontinued Operations (Details) - property		12 Months Ended
	Jan. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Brookedale MTCA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties disposed	18	18	18
Held-for-sale | Senior Housing Triple Net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale		41	90
Held-for-sale | Medical Office
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale		6	2
Held-for-sale | Senior Housing Operating Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale		97	115
Held-for-sale | Senior Housing Operating Portfolio Joint Venture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale		1	4