Notes and Other Receivables - Allowance for credit loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 751
Provision for credit losses	(141)	$ (687)	$ 0
Ending balance	756	751
Mezzanine and Bridge Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	751
Provision for credit losses	5
Ending balance	756	751
Mezzanine Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	751
Provision for credit losses	(80)
Ending balance	671	751
Bridge Loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0
Provision for credit losses	85
Ending balance	$ 85	$ 0