Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Share/Unit Repurchase Program And Dividend Reinvestment And Stock Purchase Plan) (Narrative) (Details) - USD ($) |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2019 |
Dec. 31, 2012 |
|
| Stockolders Equity [Line Items] | ||
| Date share repurchase program was initiated | September 2012 | |
| Capacity of share repurchase program | $ 150,000,000 | |
| Shares purchased and retired | 394,625 | |
| Aggregate cost of stock repurchased | $ 11,000,000 | |
| Capacity available for additional repurchase of outstanding common stock | $ 139,000,000 | |
| Proceeds from sale of common units | $ 11,000,000 | |
| Dividend Reinvestment And Stock Purchase Plan [Member] | ||
| Stockolders Equity [Line Items] | ||
| Common stock reserved for future issuance | 5,500,000 | |
| Monthly cash investment without restriction, maximum | $ 5,000 |