Mack-Cali Realty Corporation Stockholders' Equity (Share Repurchase Program And Dividend Reinvestment And Stock Purchase Plan) (Narrative) (Details) - USD ($)  | 
9 Months Ended | 34 Months Ended | 
|---|---|---|
Sep. 30, 2015  | 
Jun. 30, 2015  | 
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| 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 | |
| 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 | 
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- Definition Date Share Repurchase Program was initiated. No definition available. 
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- Definition Monthly cash investment without restriction, maximum. No definition available. 
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- Definition Stockolders Equity [Line Items] No definition available. 
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- Definition Aggregate number of common shares reserved for future issuance. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The cash outflow to reacquire common and preferred stock. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of stock repurchase plan authorized. No definition available. 
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- Definition Amount remaining of a stock repurchase plan authorized. No definition available. 
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- Definition Number of shares that have been repurchased and retired during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
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