Fair Value Measurements - Summary of Carrying Amounts and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 39,519	$ 38,894
Total liabilities	48	317
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred equity investments	36,042	35,817
Total assets	36,042	35,817
Notes and mortgages payable	3,599,800	3,583,100
Total liabilities	3,599,800	3,583,100
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred equity investments	36,339	36,112
Total assets	36,339	36,112
Notes and mortgages payable	3,617,961	3,596,953
Total liabilities	$ 3,617,961	$ 3,596,953