Quarterly report pursuant to Section 13 or 15(d)

Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Earnings Per Share/Unit) (Narrative) (Details)

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Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Earnings Per Share/Unit) (Narrative) (Details) - $ / shares
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Mar. 31, 2019
Dec. 31, 2018
Mar. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested stock outstanding 26,136 71,161 26,136 71,161 66,321 67,289 74,413 108,318
Dividends declared per common share $ 0.20 $ 0.20 $ 0.40 $ 0.40        
Mack-Cali Realty LP [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Dividends declared per common share $ 0.20 $ 0.20 $ 0.40 $ 0.40        
Unvested Restricted Stock [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested stock outstanding 26,136 71,161 26,136 71,161        
Unvested Restricted Stock [Member] | Mack-Cali Realty LP [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested stock outstanding 26,136 71,161 26,136 71,161        
Unvested LTIP Units [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested stock outstanding 1,826,331 1,795,747 1,826,331 1,795,747        
Unvested LTIP Units [Member] | Mack-Cali Realty LP [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested performance shares     1,826,331 1,795,747        
Unvested AO LTIP Units [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested stock outstanding 625,000 0 625,000 0        
Unvested AO LTIP Units [Member] | Mack-Cali Realty LP [Member]                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Unvested stock outstanding 625,000 0 625,000 0