Fair Value Measurements (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Financial Assets And Liabilities Measured At Fair Value
Marketable securities	$ 31,206,000
Liabilities measured at fair value	0	0
Assets
Short-term Investments	0	5,000,000
Liabilities
Mortgages payable	1,065,916,000	1,080,932,000
Carrying Reported Amount Fair Value Disclosure [Member]
Assets
Short-term Investments	0	5,000,000
Cash Equivalents	289,054,000	35,000,000
Total assets not measured at fair value	289,054,000	40,000,000
Liabilities
Mortgages payable	1,065,916,000	1,080,932,000
Leasing commissions (included in amounts due to Vornado)	45,803,000	40,728,000
Total liabilities not measured at fair value	1,111,719,000	1,121,660,000
Estimate Of Fair Value Fair Value Disclosure [Member]
Assets
Short-term Investments	0	5,000,000
Cash Equivalents	289,054,000	35,000,000
Total assets not measured at fair value	289,054,000	40,000,000
Liabilities
Mortgages payable	1,097,000,000	1,102,000,000
Leasing commissions (included in amounts due to Vornado)	46,000,000	41,000,000
Total liabilities not measured at fair value	1,143,000,000	1,143,000,000
Fair Value, Inputs, Level 1 [Member]
Financial Assets And Liabilities Measured At Fair Value
Marketable securities	31,206,000
Fair Value, Inputs, Level 2 [Member]
Financial Assets And Liabilities Measured At Fair Value
Marketable securities	0
Fair Value, Inputs, Level 3 [Member]
Financial Assets And Liabilities Measured At Fair Value
Marketable securities	$ 0