Dispositions - Additional Information (Details)	May 03, 2017 USD ($) ft²	Jun. 30, 2018 ft²
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Area of office and retail properties | ft²		12,500,000
Waterview [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Area of office and retail properties | ft²	636,768
Sale agreement amount | $	$ 460,000,000
Net gain on sale of property | $	$ 110,583,000