Acquisitions, Dispositions and Other Significant Transactions - Revenue of Disposal Groups (Details) - Communities Disposed of Through Sale and Lease Terminations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Resident fees	$ 11,916	$ 53,308	$ 134,294
Facility operating expense	12,822	53,033	124,324
Cash lease payments	1,726	6,752	11,014
Assisted Living and Memory Care
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Resident fees	5,445	24,105	60,204
Facility operating expense	5,142	22,723	52,228
CCRCs
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Resident fees	6,471	29,203	74,090
Facility operating expense	$ 7,680	$ 30,310	$ 72,096