Investments in and Advances to Unconsolidated Joint Ventures - Narrative (Details) $ in Thousands, £ in Millions	1 Months Ended		12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2019 GBP (£)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	May 31, 2021	Jan. 31, 2020
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity			$ 42,000	$ 33,000
Impairment charge					$ 6,000
Losses on sales of investment real estate			$ (190,590)	$ (90,350)	40
CCRC JV Investment
Schedule of Equity Method Investments [Line Items]
Impairment charge					$ 12,000
Investment ownership percentage	49.00%	49.00%			49.00%	49.00%	49.00%
U.K. JV
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage	49.00%	49.00%			49.00%
Proceeds from sale of equity method investments	$ 91,000	£ 70
Loss on sale of properties	7,000
Losses on sales of investment real estate	$ 1,000