Investment in Unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands				3 Months Ended
		Mar. 28, 2022 USD ($) ft² loanExtension years	Mar. 27, 2022 USD ($) years loanExtension	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Feb. 02, 2022 ft²	Jan. 18, 2022 ft²	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Secured Debt				$ 3,268,745				$ 3,267,914
Payment for Debt Extinguishment or Debt Prepayment Cost				0	$ 185
Loss from early extinguishment of debt				$ 0	(898)
651 Gateway | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage							50.00%
Platform 16 | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage						55.00%
Net Rentable Area (in sf) | ft²						1,100,000
Metropolitan Square | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		20.00%
Net Rentable Area (in sf) | ft²		657,000
Secured Debt		$ 420,000	$ 294,100
Debt Instrument, Description of Variable Rate Basis			the greater of (x) LIBOR or (y) 0.65%
Debt Instrument, Basis Spread on Variable Rate		2.75%	4.75%
Number of extensions | loanExtension		3	2
Extension Option (in years) | years		1	1
Payment for Debt Extinguishment or Debt Prepayment Cost		$ 0
Loss from early extinguishment of debt		(1,300)
Proceeds from mortgage notes payable		100,500
Platform 16
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[1]			55.00%
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Secured Debt				$ 3,370,649				$ 3,214,961
Loss from early extinguishment of debt				$ (1,327)	$ 0
Company's Share [Member] | Metropolitan Square
Schedule of Equity Method Investments [Line Items]
Proceeds from mortgage notes payable		$ 20,100
Construction | 651 Gateway | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²							327,000
Construction | Platform 16 | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²						390,000

[1] This entity is a VIE (See Note 2).