Dispositions - Additional Information (Details)		9 Months Ended
	Sep. 26, 2019 USD ($) ft²	Sep. 30, 2020 USD ($) ft²	May 27, 2020 USD ($) ft² $ / ft²	Mar. 06, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Area of office and retail properties | ft²		13,100,000
Notes and mortgages payable		$ 3,819,434,000			$ 3,809,643,000
1633 Broadway [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Sale percentage of office and retail properties			10.00%
Area of office and retail properties | ft²			2,500,000
Valuation of office and retail properties			$ 2,400,000,000
Cost per square foot | $ / ft²			960
Notes and mortgages payable			$ 1,250,000,000
Sale agreement amount			$ 111,984,000
Minority interest in joint ventures decrease, percentage		10.00%
1899 Pennsylvania Avenue [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Area of office and retail properties | ft²				191,000
Sale agreement amount				$ 115,000,000
Liberty Place [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Area of office and retail properties | ft²	172,000
Sale agreement amount	$ 154,500,000
Gain on sale of property	$ 1,140,000