Segment Information - Unconsolidated Real Estate Ventures of Company's Reportable Segments (Parenthetical) (Details)	Jun. 30, 2019 ft² property	Dec. 11, 2018 ft² property
Segment Reporting Information [Line Items]
Number of Properties | property	96
Area of Real Estate Property | ft²	16,922,019
DRA Austin Venture [Member]
Segment Reporting Information [Line Items]
Equity method investment, ownership percentage		50.00%
Number of Properties | property		12
Area of Real Estate Property | ft²		1,570,123