Reporting Segments and Related Information - Revenue Components of Real Estate Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from External Customer [Line Items]
Equity in earnings of unconsolidated joint ventures, net	$ 1,093	$ 2,199	$ 3,629	$ 5,046
Total expenses	14,340	12,125	33,974	34,160
Operating results from commercial/industrial and unconsolidated joint ventures	787	44	485	1,190
Real estate - commercial/industrial
Revenue from External Customer [Line Items]
Commercial/industrial revenues	2,710	2,620	7,144	12,041
Equity in earnings of unconsolidated joint ventures, net	1,093	2,199	3,629	5,046
Commercial/industrial revenues and equity in earnings of unconsolidated joint ventures	3,803	4,819	10,773	17,087
Total expenses	2,026	1,968	5,704	8,353
Operating results from commercial/industrial and unconsolidated joint ventures	$ 1,777	$ 2,851	$ 5,069	$ 8,734