Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real estate
Disaggregation of revenue
Revenue	$ 87,627	$ 61,488	$ 52,183
Homebuilder homesite sales, Lot residuals
Disaggregation of revenue
Revenue	1,900	2,500	1,000
Homebuilder homesite sales, Certain products and services
Disaggregation of revenue
Revenue	$ 1,900	$ 2,300	$ 1,100