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 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Dividends declared per common share     $ 0 $ 0.40
Mack-Cali Realty LP [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Distribution declared per common unit $ 0 $ 0 $ 0 $ 0.40