Reporting Segments and Related Information - Revenue Components of Real Estate Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from External Customer [Line Items]
Commercial revenues	$ 37,830	$ 49,523	$ 45,619
Equity in earnings of unconsolidated joint ventures	4,504	16,575	3,834
Commercial expenses	44,577	50,954	45,183
Operating results from commercial and unconsolidated joint ventures	82	14,559	5,555
Real estate - commercial/industrial
Revenue from External Customer [Line Items]
Commercial revenues	9,536	16,792	8,970
Equity in earnings of unconsolidated joint ventures	4,504	16,575	3,834
Commercial revenues and equity in earnings of unconsolidated joint ventures	14,040	33,367	12,804
Commercial expenses	7,122	12,961	6,246
Operating results from commercial and unconsolidated joint ventures	$ 6,918	$ 20,406	$ 6,558