Quarterly report pursuant to Section 13 or 15(d)

Noncontrolling Interests In Subsidiaries (Narrative) (Details)

v3.20.2
Noncontrolling Interests In Subsidiaries (Narrative) (Details)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 05, 2015
shares
Sep. 30, 2020
property
shares
Mar. 31, 2019
shares
Sep. 30, 2020
USD ($)
property
shares
Dec. 31, 2019
Noncontrolling Interest [Line Items]          
Number of common shares received upon redemption of common units   1   1  
Rebalance of ownership percentage | $       $ 1.5  
Shares granted 800,000 172,495      
Exercisable period       10 years  
Participation Rights [Member]          
Noncontrolling Interest [Line Items]          
Number of properties | property   1   1  
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]          
Percentage of noncontrolling interest   9.60%   9.60% 9.60%
Future Developments [Member] | Participation Rights [Member]          
Noncontrolling Interest [Line Items]          
Number of properties | property   1   1  
Disposal Group, Not Discontinued Operations [Member] | Flex Portfolio [Member]          
Noncontrolling Interest [Line Items]          
Proceeds from sale of properties | $       $ 2.2  
Redemption of common units, shares       99,952  
AO LTIP Units Award [Member]          
Noncontrolling Interest [Line Items]          
Exercisable period       10 years  
AO LTIP Units Award [Member] | Messr DeMarco, CEO [Member]          
Noncontrolling Interest [Line Items]          
Shares granted     625,000 625,000