Investment in Unconsolidated Real Estate Ventures - Textual (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Feb. 02, 2021 USD ($)	Jun. 30, 2021 USD ($) ft² a property apartment	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) ft² a property apartment	Jun. 30, 2020 USD ($)	Jul. 23, 2021 USD ($)	Feb. 02, 2021 ft²	Feb. 02, 2021 a	Feb. 02, 2021	Dec. 31, 2020 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Properties | property		81		81
Investment in unconsolidated real estate ventures		$ 441,464		$ 441,464						$ 401,327
Accounts receivable		10,667		10,667						13,536
Investment in joint venture		422,333		422,333						389,811
3025 JFK Venture
Schedule of Equity Method Investments [Line Items]
Area of land (in acres)							1	1
Equity method investment, ownership percentage									55.00%
Lease agreement term	99 years
Investment in joint venture	$ 34,800
Area of building to be constructed | ft²							570,000
Estimated project cost	287,300
Joint venture, funding committed by other party	45,200
Ownership interest held by partner									45.00%
Joint venture, funding committed	$ 20,500
Joint venture, amount funded		11,800		11,800
3025 JFK Venture | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Construction loan amount						$ 186,700
Construction loan, interest rate						3.75%
Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Accounts receivable		1,900		1,900						$ 1,200
Management Fees | Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Service and other revenue		2,100	$ 800	4,100	$ 1,100
Leasing Commission Income | Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Service and other revenue		$ 600	$ 200	$ 1,900	$ 300
Minimum
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		15.00%		15.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		70.00%		70.00%
Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated real estate ventures		$ 422,300		$ 422,300
Unconsolidated Real Estate Ventures | Office properties
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		5		5
Rentable area (in square feet) | ft²		8,400,000		8,400,000
Unconsolidated Real Estate Ventures | Other Liabilities
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated real estate ventures		$ (19,100)		$ (19,100)
Unconsolidated Real Estate Ventures | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Number of Properties | property		10		10
Number of properties with negative investment balances | property		1		1
Unconsolidated Real Estate Ventures | Land Held For Development
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		2		2
Area of land (in acres) | a		1.4		1.4
Unconsolidated Real Estate Ventures | Land Under Active Development
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		1		1
Area of land (in acres) | a		1.0		1.0
Unconsolidated Real Estate Ventures | Mixed Use Tower
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		1		1
Rentable area (in square feet) | ft²		200,000		200,000
Number of apartment units (in units) | apartment		250		250
Unconsolidated Real Estate Ventures | Residential Tower
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		1		1
Number of apartment units (in units) | apartment		321		321