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The expiration, mandatory redemption, or due date, month and year (YYYY-MM), of the financial instrument issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Investment in Unconsolidated Joint Venture - Additional Information (Detail) - Worldwide Plaza [Member] - USD ($) $ in Millions			6 Months Ended
	Oct. 18, 2017	Jun. 01, 2017	Jun. 30, 2024	Oct. 30, 2013
Schedule of Equity Method Investments [Line Items]
Ownership percentage			50.10%	48.90%
Aggregate cost		$ 276.7		$ 220.1
Agreed upon value				1,300.0
Notes payable				$ 875.0
Additional acquire percentage		49.90%
Purchase obligation		$ 1,400.0
Mortgage notes payable		$ 875.0
Joint venture partner's right to maintain minimum ownership percentage		1.20%
Debt refinance amount	$ 1,200.0
Cash received from sale and excess proceeds from financing	446.5
Defeasance and prepayment costs	108.3
Reserved amount	$ 90.7
Debt blended rate	3.98%
Maturity date			2027-11
Property selling percentage			100.00%
Option to purchase percentage of property			100.00%
Property purchase option period			45 days
Re-offer property selling percentage			92.50%
SL Green Realty Corp. and RXR Realty LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	48.70%
Liquidation value of property	$ 1,725.0
Liquidation Value [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		98.80%