Annual report pursuant to Section 13 and 15(d)

Mack-Cali Realty Corporation Stockholders' Equity (Share Repurchase Program And Dividend Reinvestment And Stock Purchase Plan) (Narrative) (Details)

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Mack-Cali Realty Corporation Stockholders' Equity (Share Repurchase Program And Dividend Reinvestment And Stock Purchase Plan) (Narrative) (Details) (USD $)
 12 Months Ended 28 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2014
Mack Cali Realty Corporation Stockholders Equity [Line Items]      
Date share repurchase program was initiated September 2012    
Capacity of share repurchase program $ 150,000,000us-gaap_StockRepurchaseProgramAuthorizedAmount1   $ 150,000,000us-gaap_StockRepurchaseProgramAuthorizedAmount1
Shares purchased and retired 0us-gaap_StockRepurchasedAndRetiredDuringPeriodShares 0us-gaap_StockRepurchasedAndRetiredDuringPeriodShares 394,625us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Aggregate cost of stock repurchased     11,000,000us-gaap_PaymentsForRepurchaseOfEquity
Capacity available for additional repurchase of outstanding common stock 139,000,000us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1   139,000,000us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Dividend Reinvestment And Stock Purchase Plan [Member]      
Mack Cali Realty Corporation Stockholders Equity [Line Items]      
Common stock reserved for future issuance 5,500,000us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_StatementScenarioAxis
= cli_DividendReinvestmentAndStockPurchasePlanMember 		  5,500,000us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_StatementScenarioAxis
= cli_DividendReinvestmentAndStockPurchasePlanMember
Monthly cash investment without restriction, maximum $ 5,000cli_MonthlyCashInvestmentWithoutRestrictionMaximum
/ us-gaap_StatementScenarioAxis
= cli_DividendReinvestmentAndStockPurchasePlanMember