Properties Held for Sale and Property Dispositions (Details) $ in Millions	1 Months Ended
Mar. 31, 2020 USD ($) ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Approximate Square Feet \| ft²	29,864,846
315 West 33rd Street
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Price	$ 446.5
Approximate Square Feet \| ft²	492,987
Gain (loss)	$ 72.3
Accrued employee compensation in connection with realization of investment	$ 6.0

Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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