Acquisitions, Dispositions and Other Transactions - Additional Information (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) community	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) community
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating and financing leases, number of communities	306
Number of communities managed by third party	80
Assets held for sale | $	$ 37,397		$ 42,671
Gain (loss) on sale of assets, net | $	$ 372,839	$ (702)
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	15
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	11
Sale of 6 communities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities disposed of			6
Net cash proceeds | $			$ 29,500
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	1		14
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | 1 Community
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash proceeds | $	$ 5,500
Gain (loss) on sale of assets, net | $	$ 200
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Two Communities 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	2
Assets held for sale | $	$ 37,400
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 (loss) on sale of assets, net | $			$ 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	355
Operating and financing leases, number of communities	306
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	26
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