Acquisitions, Dispositions and Other Transactions - Additional Information (Details) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($) community	Mar. 31, 2020 USD ($) community	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) community	Sep. 30, 2019 USD ($) community	Dec. 31, 2019 USD ($) community	Aug. 31, 2020 community	Jul. 26, 2020 community
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities acquired	1
Number of communities disposed of					8
Purchase price | $	$ 25,000
Number of communities owned							16
Operating and financing leases, number of communities	302			302
Assets held for sale | $	$ 8,324			$ 8,324		$ 42,671
Gain on sale of assets | $	$ 2,209		$ 579	$ 374,019	$ 2,723
Communities Disposed of Through Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities disposed of				21
Sale of 8 communities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash proceeds | $					44,100
Gain on sale of assets | $					$ 900
Mortgage notes payable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payment for debt extinguishment or debt prepayment cost | $						$ 5,100
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Communities Disposed of Through Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities disposed of				2		14
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Communities Disposed of Through Lease Terminations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities disposed of				14
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | One Community Held For Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities classified as held for sale	1
Assets held for sale | $	$ 8,300			$ 8,300
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Sale of 7 Communities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash proceeds | $				38,100
Gain on sale of assets | $				$ 2,700
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Sale of 14 Communities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash proceeds | $						$ 85,400
Gain on sale of assets | $						$ 5,500
Current Property Ownership Status
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities owned	350			350
Operating and financing leases, number of communities	302			302
Number of communities managed by third party	74			74
Communities Acquired Previously Leased Or Managed
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities acquired				27
Healthpeak
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities acquired		8
Purchase price | $		$ 39,300
Healthpeak | Communities Acquired Previously Leased Or Managed
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities acquired		18
Ventas, Inc
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of owned communities transferred								5