Dispositions and Assets Held for Sale - Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Aug. 06, 2020 USD ($)	Jun. 30, 2020 USD ($) property properties	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($) property	Dec. 31, 2019 USD ($)	[1]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real property held for sale		$ 382,580		$ 382,580	$ 1,253,008
Impairment of assets held for sale				18,780
Subsequent event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected proceeds from properties held for sale	$ 501,008
Held for sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Secured debt		12,849		12,849
Net other assets and liabilities		35,085		$ 35,085
Net impairment charges		$ 56,371	$ 27,827
Seniors Housing Operating
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale | property		7		7
Number of properties reclassified as held for use | properties		11
Assets held for use		$ 386,744		$ 386,744
Seniors Housing Operating | Held for sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale | property		6		6
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 | property		3		3
Outpatient Medical
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties classified as held for sale | property		13		13

[1] The consolidated balance sheet at December 31, 2019 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements.