Quarterly report pursuant to Section 13 or 15(d)

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Restricted Stock Awards And Performance Share Units) (Narrative) (Details)

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Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Restricted Stock Awards And Performance Share Units) (Narrative) (Details) - USD ($)
3 Months Ended
Jun. 05, 2018
Jun. 05, 2015
Mar. 31, 2020
Dec. 31, 2019
Mar. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unvested stock outstanding     42,690 42,690 66,321 67,289
Performance period     3 years      
Restricted Stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unvested stock outstanding     42,690      
Restricted Stock [Member] | 2013 Incentive Stock Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares granted   37,550.54        
Performance period     3 years      
Restricted Stock [Member] | Minimum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock compensation vesting period     1 year      
Restricted Stock [Member] | Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock compensation vesting period     7 years      
Unvested Restricted Stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unvested stock outstanding     42,690   66,321  
Total Stockholder Return Based Awards [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Total unrecognized compensation cost     $ 300,000      
Total unrecognized compensation cost, period of recognition     2 months 12 days      
Performance Shares [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unvested performance shares     0      
Total unrecognized compensation cost     $ 0      
Performance Shares [Member] | 2013 Incentive Stock Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares granted   112,651.64        
Performance period     3 years      
Performance Shares [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Percentage of shares vested 100.00%          
Performance Shares [Member] | Minimum [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Percentage of shares vested     0.00%      
Performance Shares [Member] | Maximum [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Percentage of shares vested     150.00%