Fair Value of Financial Instruments - Summary of Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Mortgages payable and notes payable | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	$ 455,046	$ 753,406
Mortgages payable and notes payable | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	460,416	751,361
Senior notes and debentures | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	2,702,737	2,404,279
Senior notes and debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	$ 2,830,445	$ 2,371,392