Annual report pursuant to Section 13 and 15(d)

Noncontrolling Interests In Subsidiaries (Narrative) (Details)

v3.8.0.1
Noncontrolling Interests In Subsidiaries (Narrative) (Details)
$ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2017
USD ($)
shares
Dec. 31, 2017
property
shares
Dec. 31, 2016
USD ($)
Noncontrolling Interest [Line Items]      
Number of common shares received upon redemption of common units | shares   1  
Rebalance of ownership percentage     $ 4.6
Percentage of noncontrolling interest   10.40% 10.50%
Cash consideration $ 2.0    
Issuance of common units | shares 99,412    
Common unit value $ 2.8    
Participation Rights [Member]      
Noncontrolling Interest [Line Items]      
Number of properties | property   2  
Excess net cash flow remaining after the distribution to the Company   50.00%  
Internal rate of return   10.00%  
Mack-Cali Realty LP [Member]      
Noncontrolling Interest [Line Items]      
Cash consideration $ 2.0    
Issuance of common units | shares 99,412    
Common unit value $ 2.8    
Future Developments [Member] | Participation Rights [Member]      
Noncontrolling Interest [Line Items]      
Number of properties | property   1