Summary Of Significant Accounting Policies Recently Adopted Accounting Pronouncements (Details) - USD ($)	Sep. 30, 2016	Jan. 01, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Mortgages payable of VIEs previously consolidated as voting interest entities	$ 441,294,000		$ 448,315,000
Pike and Rose Hotel JV
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investment in variable interest entity		$ 6,600,000
Maximum exposure to loss in variable interest entity		$ 13,500,000
Adjustments for New Accounting Pronouncement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of variable interest entities previously consolidated as voting interest entities		10
Unamortized Debt Issuance Costs			$ 15,200,000
Adjustments for New Accounting Pronouncement | Previous voting interest entity
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net real estate assets of VIEs previously consolidated as voting interest entities		$ 566,100,000
Mortgages payable of VIEs previously consolidated as voting interest entities		$ 194,900,000