Stockholders' Equity (Stockholders Agreements) (Details)
Sep. 16, 2011
Aug. 19, 2011
Stockholders' Equity [Abstract]    
Stockholders Agreements On September 16, 2011, we entered into a stockholder agreement with Vornado that, among other things, prohibits Vornado from purchasing shares of our common stock and derivative securities whose value is derived from the value of our common stock in excess of 15.4% of the shares of our common stock outstanding and permits Vornado to designate one member of our Board of Directors. Pursuant to the stockholder agreement, Vornado may vote the number of shares that it owns up to a maximum of 9.9% of the shares of our common stock outstanding and is required to vote the number of any excess shares of our common stock that they beneficially own to be present and voted at stockholder meetings either as recommended by our Board of Directors or in direct proportion to how all other stockholders vote. On August 19, 2011, we entered into a stockholder agreement with Pershing Square that, among other things, prohibits Pershing Square from purchasing shares of our common stock and derivative securities whose value is derived from the value of our common stock in excess of 26.1% of the shares of our common stock outstanding and permits Pershing Square to designate one member of our Board of Directors. Pursuant to the August stockholder agreement, Pershing Square will be able to direct the vote of between 15%-16.5% of the shares of our common stock outstanding (depending on their ownership percentage of our common stock and related derivative securities) and will be required to vote the number of any excess shares of our common stock that they beneficially own to be present and voted at stockholder meetings either as recommended by our Board of Directors or in direct proportion to how all other stockholders vote.