Annual report pursuant to Section 13 and 15(d)

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)

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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 ($)
 12 Months Ended 64 Months Ended
Dec. 31, 2017
Dec. 31, 2012
Dec. 31, 2017
Stockolders Equity [Line Items]      
Date share repurchase program was initiated September 2012    
Capacity of share repurchase program $ 150,000,000   $ 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   $ 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   5,500,000
Monthly cash investment without restriction, maximum $ 5,000