Real Estate Loans, Notes Receivable, and Lines of Credit - Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total allowance for expected credit losses	$ 874	$ 6,103
Haven Campus Communities, Line Of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net increases (decreases) in current expected loss reserves on existing loans	1,644	1,649
Starkville Real Estate Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net increases (decreases) in current expected loss reserves on existing loans	0	652
Existing Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net increases (decreases) in current expected loss reserves on existing loans	$ (770)	$ 3,802