Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Schedule Of Reconciliation Of Shares Used In Basic EPS Calculation To Shares Used In Diluted EPS Calculation) (Details) - shares
shares in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Stockolders Equity [Line Items]      
Basic EPS shares 90,388 90,005 89,746
Add: Operating Partnership - common and vested LTIP Units 10,246 10,405 10,499
Restricted Stock Awards   40 43
Stock Options 90 253 210
Diluted EPS Shares 100,724 100,703 100,498
Mack-Cali Realty LP [Member]      
Stockolders Equity [Line Items]      
Basic EPS units 100,634 100,410 100,245
Restricted Stock Awards   40 43
Stock Options 90 253 210
Diluted EPU Units 100,724 100,703 100,498