The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of investment in equity method investee and investment in and advance to affiliate.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 210
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-Section S99
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ale Of Ownership Interest Percent in real estate property sold.

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Investments in Partially Owned Entities (Summary of Investments) (Details) - USD ($) $ in Thousands	May 27, 2016	Sep. 30, 2018	Dec. 31, 2017
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities		$ 909,440	$ 1,056,829
Other liabilities
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities		$ (107,582)	(101,368)
7 West 34th Street \| Other liabilities
Schedule Of Equity Method Investments
Equity method ownership percentage		53.00%
Carrying amount of investments in partially owned entities		$ (49,647)	(47,369)
Sale of ownership interest, percent	47.00%
330 Madison Avenue \| Other liabilities
Schedule Of Equity Method Investments
Equity method ownership percentage		25.00%
Carrying amount of investments in partially owned entities		$ (57,935)	(53,999)
Partially Owned Office Buildings
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities		$ 502,826	504,393
Alexanders Inc
Schedule Of Equity Method Investments
Equity method ownership percentage		32.40%
Carrying amount of investments in partially owned entities		$ 111,842	126,400
PREIT
Schedule Of Equity Method Investments
Equity method ownership percentage		7.90%
Carrying amount of investments in partially owned entities		$ 61,514	66,572
UE
Schedule Of Equity Method Investments
Equity method ownership percentage		4.50%
Carrying amount of investments in partially owned entities		$ 45,398	46,152
Other investments
Schedule Of Equity Method Investments
Carrying amount of investments in partially owned entities		$ 187,860	$ 313,312