Commitments And Contingencies (Construction Projects) (Narrative) (Details)
$ in Thousands
 6 Months Ended
Jun. 30, 2017
USD ($)
item
Jun. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
item
Dec. 31, 2015
item
Commitments And Contingencies [Line Items]        
Amount outstanding $ 770,388   $ 634,069  
Investment in unconsolidated joint ventures 11,422 $ 23,657    
Cash consideration 2,000      
XS Hotel Urban Renewal Associates LLC [Member]        
Commitments And Contingencies [Line Items]        
Percentage of interest in venture       90.00%
Costs of the project incurred $ 74,800      
Delivery date to tenant second quarter 2018      
Number of units | item       372
Total project costs $ 139,400      
City Square Project [Member]        
Commitments And Contingencies [Line Items]        
Costs of the project incurred 60,000      
Total project costs $ 92,000      
City Square Project Phase One [Member]        
Commitments And Contingencies [Line Items]        
Delivery date to tenant fourth quarter 2017      
Number of units | item       237
City Square Project Phase Two [Member]        
Commitments And Contingencies [Line Items]        
Delivery date to tenant third quarter 2018      
Number of units | item       128
Signature Place Project [Member]        
Commitments And Contingencies [Line Items]        
Costs of the project incurred $ 35,100      
Delivery date to tenant fourth quarter of 2017      
Number of units | item     197  
Total project costs $ 58,700      
Portside 5/6 Project [Member]        
Commitments And Contingencies [Line Items]        
Costs of the project incurred $ 64,900      
Delivery date to tenant second quarter 2018      
Number of units | item 296      
Total project costs $ 111,400      
Riverhouse 11 Project [Member]        
Commitments And Contingencies [Line Items]        
Costs of the project incurred $ 63,200      
Delivery date to tenant first quarter 2018      
Number of units | item 295      
Total project costs $ 124,000      
51 Washington Street Project [Member]        
Commitments And Contingencies [Line Items]        
Costs of the project incurred $ 22,300      
Delivery date to tenant second quarter 2019      
Number of units | item 310      
Total project costs $ 89,400      
Construction Loan [Member] | XS Hotel Urban Renewal Associates LLC [Member]        
Commitments And Contingencies [Line Items]        
Maximum borrowing capacity 94,000      
Amount outstanding 24,900      
Construction Loan [Member] | City Square Project [Member]        
Commitments And Contingencies [Line Items]        
Maximum borrowing capacity 58,000      
Amount outstanding 16,400      
Construction Loan [Member] | Signature Place Project [Member]        
Commitments And Contingencies [Line Items]        
Amount outstanding 14,000      
Amount to fund 42,000      
Construction Loan [Member] | Portside 5/6 Project [Member]        
Commitments And Contingencies [Line Items]        
Amount outstanding 16,500      
Amount to fund 73,000      
Construction Loan [Member] | Riverhouse 11 Project [Member]        
Commitments And Contingencies [Line Items]        
Amount outstanding 30,000      
Amount to fund 78,000      
Development Property [Member] | Riverhouse 11 Project [Member]        
Commitments And Contingencies [Line Items]        
Costs of the project incurred 32,800      
Amount to fund $ 46,000      
Unconsolidated Joint Venture Hotel [Member]        
Commitments And Contingencies [Line Items]        
Number of units | item 350