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 |