Investment in Unconsolidated Joint Ventures (Narrative) (Details)																		1 Months Ended	12 Months Ended
		Dec. 31, 2023 USD ($) ft²	Dec. 14, 2023 USD ($) ft² floor	Oct. 31, 2023 USD ($)	Oct. 02, 2023 USD ($)	Sep. 13, 2023 USD ($) ft²	Sep. 06, 2023 USD ($) ft²	Sep. 05, 2023 USD ($)	Aug. 11, 2023	Jul. 28, 2023 USD ($) Integer	Jul. 27, 2023 USD ($)	Jun. 28, 2023	Jun. 27, 2023 USD ($)	Jun. 02, 2023	Apr. 21, 2023 ft² Year	Apr. 20, 2023 USD ($)	Jan. 31, 2023 USD ($) a ft² Vehicles Building	Aug. 13, 2023	Dec. 31, 2023 USD ($) ft²		Dec. 31, 2022 USD ($)		Dec. 31, 2021 USD ($)		Dec. 13, 2023	Oct. 30, 2023 ft²	Sep. 12, 2023 USD ($)	Sep. 08, 2023 USD ($)	Sep. 01, 2023 ft²	Jun. 30, 2023 ft²	Jun. 05, 2023 USD ($) ft²	Jun. 04, 2023 USD ($)
Schedule of Equity Method Investments [Line Items]
Interest and Other Income																			$ 69,964,000		$ 11,940,000		$ 5,704,000
Sales-type lease receivable, net		$ 13,953,000																	13,953,000		13,028,000
Gain on sales-type lease																			0		10,058,000		0
Mortgages [Member]
Schedule of Equity Method Investments [Line Items]
Long-Term Debt		4,200,000,000																	4,200,000,000
Related Party
Schedule of Equity Method Investments [Line Items]
Related party note receivable		$ 88,779,000																	$ 88,779,000		78,576,000
3 Hudson Boulevard [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		25.00%																	25.00%
Net Rentable Area (in sf) | ft²		2,000,000																	2,000,000
Interest Expense, Long-Term Debt		$ 28,000,000
3 Hudson Boulevard [Member] | Related Party
Schedule of Equity Method Investments [Line Items]
Interest and Other Income																			$ 8,900,000		$ 5,600,000		3,600,000
200 Fifth Avenue JV LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[1]	26.69%																	26.69%
Impairment loss on investment																			$ 33,400,000
Office Tower Developer LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%																	50.00%
Gateway Commons Complex [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%																	50.00%
Podium Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%																	50.00%
BP/CRF Metropolitan Square LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[2]																				20.00%
Gain on Unconsolidated Joint Venture Investment																			$ 35,800,000
Platform 16
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[1],[3]	55.00%																	55.00%
Impairment loss on investment																			$ 155,200,000
capitlization rate																			6.00%
Discount Rate																			12.00%
360 PAS Holdco LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[1],[4]	71.11%																	71.11%
Impairment loss on investment																			$ 54,000,000
360 PAS Holdco LLC | Scenario, Plan | Joint Venture Partner [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		29.00%																	29.00%
Safeco Plaza REIT LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[1],[5]	33.67%																	33.67%
Impairment loss on investment																			$ 29,900,000
Santa Monica Business Park [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	[6]																				55.00%
Santa Monica Business Park [Member] | Joint Venture Partner [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage			45.00%
Hotel Tower Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%																	50.00%
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			$ (272,603,000)	[7]	$ (50,705,000)	[7]	0
Gain on Sale of Investments																			0		0		10,257,000	[8]
Gain on Unconsolidated Joint Venture Investment																			35,756,000	[9]	0		0
Gain (loss) on sale / consolidation																			28,412,000	[9],[10]	0		0
Sales-type lease receivable, net		$ 13,900,000																	13,900,000
Gain on sales-type lease																			2,737,000		$ 0		$ 0
Unconsolidated Joint Ventures [Member] | 200 Fifth Avenue JV LLC
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			33,400,000
Unconsolidated Joint Ventures [Member] | Platform 16
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			155,200,000
Unconsolidated Joint Ventures [Member] | 360 PAS Holdco LLC
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			54,000,000
Unconsolidated Joint Ventures [Member] | Safeco Plaza REIT LLC
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			29,900,000
Unconsolidated Properties | Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			272,600,000
Worldgate Drive | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage																	50.00%
Payments to Acquire Interest in Joint Venture																	$ 17,000,000
Net Rentable Area (in sf) | ft²																	350,000
Number of buildings | Building																	2
Number of parking space | Vehicles																	1,200
Area of Land | a																	10
7750 Wisconsin Avenue [Member] | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage															50.00%
Net Rentable Area (in sf) | ft²															736,000
Construction Loan																$ 252,600,000
Debt Instrument, Description of Variable Rate Basis														Term Secured Overnight Finance Rate (“SOFR”)	LIBOR	London Interbank Offered Rate (“LIBOR”)
Debt Instrument, Basis Spread on Variable Rate															1.25%	1.25%
Extension Option (in years)															1	1
Number of extensions																2
7750 Wisconsin Avenue [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate														1.35%
500 North Capitol Street, NW | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage																															30.00%
Net Rentable Area (in sf) | ft²																															231,000
Debt																															$ 105,000,000	$ 105,000,000
Debt, Weighted Average Interest Rate																															6.83%
500 North Capitol Street, NW | Unconsolidated Properties | Related Party
Schedule of Equity Method Investments [Line Items]
Debt																															$ 105,000,000
Debt, Weighted Average Interest Rate																															6.83%
500 North Capitol Street, NW | Unconsolidated Properties | Company's Share [Member] | Related Party
Schedule of Equity Method Investments [Line Items]
Related party note receivable																															$ 10,500,000
3 Hudson Boulevard [Member] | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage												25.00%
Debt Instrument, Description of Variable Rate Basis												LIBOR	LIBOR
Debt Instrument, Basis Spread on Variable Rate												3.50%	3.50%
Debt													$ 80,000,000
Number of extensions												1	2
Extension Option (in days)													30 days
Extension Option Two (in days)									180 days				180 days
3 Hudson Boulevard [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate																		3.61%
3 Hudson Boulevard [Member] | Unconsolidated Properties | Extended Maturity
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Term												30 days
100 Causeway Street [Member] | Construction Loans
Schedule of Equity Method Investments [Line Items]
Extension Option (in years) | Integer										1
Debt										$ 336,600,000	$ 340,600,000
Repayments of Construction Loans Payable										$ 4,000,000
100 Causeway Street [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Construction Loans
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate										1.48%	1.60%
100 Causeway Street [Member] | Office Tower Developer LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage										50.00%
100 Causeway Street [Member] | Extended Maturity | Construction Loans
Schedule of Equity Method Investments [Line Items]
Fiscal Period Duration										1 year
100 Causeway Street [Member] | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²																										634,000
Leased percentage																										95.00%
751 Gateway | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Ownership Percentage																													49.00%
Net Rentable Area (in sf) | ft²																													231,000
Leased percentage																													100.00%
Hub on Causeway - Podium | Unconsolidated Properties | Podium Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage							50.00%
Net Rentable Area (in sf) | ft²							383,000
Leased percentage							94.00%
Debt Instrument, Basis Spread on Variable Rate							2.50%	2.35%
Extension Option (in years)							1
Debt							$ 154,300,000	$ 174,300,000
Repayments of Construction Loans Payable							$ 20,000,000
Derivative, Notional Amount																												$ 154,300,000
Derivative, Fixed Interest Rate																												7.35%
Metropolitan Square
Schedule of Equity Method Investments [Line Items]
Debt																											$ 420,000,000
Metropolitan Square | Senior Loans
Schedule of Equity Method Investments [Line Items]
Debt																											305,000,000
Metropolitan Square | Junior Loans
Schedule of Equity Method Investments [Line Items]
Debt																											$ 115,000,000
Metropolitan Square | Scenario, Plan
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount						$ 100,000,000
Metropolitan Square | Scenario, Plan | Affiliated Entity
Schedule of Equity Method Investments [Line Items]
Loans and Leases Receivable, Loans in Process						$ 20,000,000
Metropolitan Square | Unconsolidated Properties | BP/CRF Metropolitan Square LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage						20.00%
Net Rentable Area (in sf) | ft²						657,000
Gain on Unconsolidated Joint Venture Investment						$ 35,800,000
Gain (loss) on sale / consolidation					$ (1,500,000)
Platform 16 | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²																														390,000
Platform 16 | Unconsolidated Properties | Platform 16
Schedule of Equity Method Investments [Line Items]
Ownership Percentage																														55.00%
360 Park Avenue South | 360 PAS Holdco LLC
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			$ 54,000,000
capitlization rate																			5.50%
360 Park Avenue South | 360 PAS Holdco LLC (indirect ownership)
Schedule of Equity Method Investments [Line Items]
Ownership Percentage			71.00%
Net Rentable Area (in sf) | ft²			450,000
Net Working Capital, Including Cash Acquired from Acquisition			$ 25,400,000
Number of floors | floor			20
360 Park Avenue South | 360 PAS Holdco LLC (indirect ownership) | Joint Venture Partner [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage			29.00%
Payments to Acquire Investments			$ 1
360 Park Avenue South | 360 PAS Holdco LLC (indirect ownership) | Mortgages [Member] | Joint Venture Partner [Member]
Schedule of Equity Method Investments [Line Items]
Long-Term Debt			$ 220,000,000
360 Park Avenue South | Unconsolidated Properties | 360 PAS Holdco LLC
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²		450,000																	450,000
200 Fifth Avenue | 200 Fifth Avenue JV LLC
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			$ 33,400,000
capitlization rate																			5.00%
Discount Rate																			8.00%
200 Fifth Avenue | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²		855,000																	855,000
Safeco Plaza | Safeco Plaza REIT LLC
Schedule of Equity Method Investments [Line Items]
Impairment loss on investment																			$ 29,900,000
capitlization rate																			5.50%
Discount Rate																			8.00%
Safeco Plaza | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²		780,000																	780,000
Santa Monica Business Park [Member]
Schedule of Equity Method Investments [Line Items]
Net Rentable Area (in sf) | ft²			1,200,000
Payments to Acquire Investments			$ 38,000,000
Net Working Capital, Including Cash Acquired from Acquisition			20,000,000
Gain (loss) on sale / consolidation			29,900,000
Santa Monica Business Park [Member] | Mortgages [Member]
Schedule of Equity Method Investments [Line Items]
Debt			$ 300,000,000
Santa Monica Business Park [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Mortgages [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis			SOFR
Debt Instrument, Basis Spread on Variable Rate			1.38%
Debt			$ 300,000,000
Long-Term Debt			295,500,000
Santa Monica Business Park [Member] | Santa Monica Business Park [Member]
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale / consolidation			29,900,000
Santa Monica Business Park [Member] | Unconsolidated Properties | Santa Monica Business Park [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage																									55.00%
Payments to Acquire Investments			38,000,000
Net Working Capital, Including Cash Acquired from Acquisition			$ 20,000,000
Hub on Causeway - Hotel Air Rights | Unconsolidated Properties | Hotel Tower Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage				50.00%
Lease Income				$ 4,500,000
Sales-type lease receivable, net				18,600,000
Gain on sales-type lease				$ 2,700,000

[1] During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investment.

[2] During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

[3] At December 31, 2022, this entity was a VIE.

[4] On December 14, 2023, the Company completed the acquisition of all of one of its joint venture partners ownership interest. As a result of this acquisition, at December 31, 2023, the Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 35.02% indirect ownership in the joint venture, and (3) an additional 1% interest in the entity through which the partner owns its interest in the joint venture. The Company’s partner will fund required capital until its aggregate investment is approximately 29% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests. At December 31, 2022, the Company’s ownership included (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.

[5] The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.

[6] During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.

[7] During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively, as described below in this Note 6. During the year ended December 31, 2022, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $50.7 million.

[8] During the year ended December 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.

[9] During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

[10] During the year ended December 31, 2023, the Company acquired its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6.