Fair Value Measurements - Summary of Carrying Amounts and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 38,894	$ 22,532
Total liabilities	317	22,446
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred equity investments	35,817	55,051
Total assets	35,817	55,051
Notes and mortgages payable	3,583,100	3,408,179
Revolving credit facility		230,000
Total liabilities	3,583,100	3,638,179
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred equity investments	36,112	55,300
Total assets	36,112	55,300
Notes and mortgages payable	3,596,953	3,371,262
Revolving credit facility		230,018
Total liabilities	$ 3,596,953	$ 3,601,280