Loans Receivable - Credit Loss Roll Forward (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 224,036	$ 68,372
Provision for loan losses	7,309	11,351
Loan write-offs	(64,075)	0
Foreign currency translation	(468)	(40)
Balance at end of period	166,802	84,895	$ 68,372
Accounting Standards Update [Extensible List]			Accounting Standards Update 2016-13
Belmont Village
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loan write-offs	(64,075)
Accounting Standards Update 2016-13 | Cumulative effect, period of adoption, adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 0	$ 5,212
Balance at end of period			$ 5,212