Fair Value Measurements - Summary of Carrying Amounts and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 21,263	$ 39,519
Total liabilities	11,691	48
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred equity investments		36,042
Total assets		36,042
Notes and mortgages payable	3,603,000	3,599,800
Total liabilities	3,603,000	3,599,800
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred equity investments		36,339
Total assets		36,339
Notes and mortgages payable	3,671,118	3,617,961
Total liabilities	$ 3,671,118	$ 3,617,961