Notes and Interest Receivable - Summary of changes in provision for credit losses of mezzanine loan and ground lease investments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Notes and Interest Receivable
Provision for credit losses, beginning of the period	$ 174
Provision for credit loss on pool of assets, net (1)	401	$ 174
Provision for credit losses, end of period	$ 575	$ 174