Investment In Unconsolidated Joint Ventures (Narrative) (Details) (USD $)	12 Months Ended									12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 2001 Sixth Avenue [Member]	Dec. 31, 2012 2001 Sixth Avenue [Member]	Dec. 31, 2011 2001 Sixth Avenue [Member]	Dec. 31, 2013 2020 Fifth Avenue [Member]	Dec. 31, 2012 2020 Fifth Avenue [Member]	Dec. 31, 2011 2020 Fifth Avenue [Member]	Dec. 31, 2013 33 Chun Choi Street (Hong Kong) [Member] sqft	Dec. 31, 2012 33 Chun Choi Street (Hong Kong) [Member]	Dec. 31, 2013 Prudential [Member] sqft	Sep. 27, 2013 Prudential [Member] property	Dec. 31, 2013 Prudential [Member] Notes Payable to Banks [Member]	Dec. 31, 2013 Prudential [Member] Notes Payable to Banks [Member] London Interbank Offered Rate (LIBOR) [Member]
Schedule of Equity Method Investments [Line Items]
Contributions to joint venture								$ 57,400,000
Square footage of real estate property								164,000		1,060,473
Number of properties contributed											9
Gross Value										366,420,000
Joint venture, closing costs percentage											20.00%
Joint venture closing costs											2,800,000
Investment fund manager, ownership interest in joint venture											80.00%
Ownership percentage in joint ventures		50.00%	50.00%	50.00%	50.00%	50.00%	16.40%	50.00%	50.00%	20.00%	20.00%
Debt Instrument, Face Amount												185,000,000
Debt instrument term												5 years
Interest rate basis spread													1.80%
Loan to value ratio										50.00%
Net proceeds from joint venture										328,600,000
Gain on contribution of investment properties to unconsolidated joint venture	115,609,000
Amortization of difference from cost and book value of investment in joint venture										$ 100,000