Quarterly report pursuant to Section 13 or 15(d)

Recent Transactions (Consolidation) (Narrative) (Details)

v3.8.0.1
Recent Transactions (Consolidation) (Narrative) (Details)
$ in Thousands
 1 Months Ended 9 Months Ended
Feb. 28, 2017
USD ($)
ft²
item
shares
Feb. 03, 2017
USD ($)
shares
Apr. 30, 2017
USD ($)
shares
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Feb. 02, 2017
Dec. 31, 2016
USD ($)
Real Estate Properties [Line Items]              
Acquisition cost       $ 19,279 $ 31,318    
Consolidated joint ventures, total real estate assets       174,700     $ 201,900
Net assets acquired       $ 394,589      
Percentage of ownership interest       89.60%     89.50%
Series A-1 Units [Member]              
Real Estate Properties [Line Items]              
Percentage of ownership interest 29.00%            
Mack-Cali Realty LP [Member]              
Real Estate Properties [Line Items]              
Acquisition cost       $ 19,279 $ 31,318    
Mack-Cali Realty LP [Member] | Series A Units [Member]              
Real Estate Properties [Line Items]              
Preferred units shares issued | shares   42,800          
Percentage of interest in venture   37.50%          
Preferred unit annual rate   3.50%          
Preferred units aggregate amount   $ 42,800          
Mack-Cali Realty LP [Member] | Series A-1 Units [Member]              
Real Estate Properties [Line Items]              
Preferred units shares issued | shares 9,213   91        
Percentage of interest in venture 13.80%            
Preferred unit annual rate 3.50%            
Plaza VIII & IX Associates, L.L.C. [Member]              
Real Estate Properties [Line Items]              
Percentage of interest in venture           50.00%  
Percentage of additional interest acquired   12.50%          
Acquisition cost   $ 14,300          
Consolidated joint ventures, total real estate assets   $ 60,600          
Monaco [Member]              
Real Estate Properties [Line Items]              
Number of towers | item 2            
Net assets acquired       $ 139,886      
Garage Parking Spaces | item 558            
Number of stories | item 50            
Area of property (in square feet) | ft² 12,300            
Number of units | item 523            
Monaco [Member] | Series A-1 Units [Member]              
Real Estate Properties [Line Items]              
Percentage of interest in venture 13.80%            
Monaco [Member] | Mack-Cali Realty LP [Member] | Series A-1 Units [Member]              
Real Estate Properties [Line Items]              
Preferred units shares issued | shares 9,122   91        
Preferred units aggregate amount $ 9,100            
Acquisition cost     $ 130,900        
Debt assumed     $ 171,200        
Percentage of interest in venture     71.20%   100.00%