Real Estate Investments Acquisitions and Dispositions (Details) (Princeton Pike Corporate Center [Member], USD $) In Millions, unless otherwise specified	Feb. 25, 2013 sqft
Princeton Pike Corporate Center [Member]
Significant Acquisitions and Disposals [Line Items]
Number of real estate properties sold	8
Net Rentable Space Sold	800,546
Sale Consideration Of Sold Property	$ 121.0
Lease percentage of sold property	86.90%