Stock-Based Compensation - Compensation Cost Relating to Stock-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized in conjunction with development projects	$ 483	$ 746	$ 661
Share-based compensation cost	2,861	2,359	1,947
General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	1,615	1,211	1,073
General contracting and real estate services expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 763	$ 402	$ 213

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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