Document And Entity Information - shares
 6 Months Ended
Jun. 30, 2019
Aug. 05, 2019
Entity Registrant Name Mack-Cali Realty Corporation  
Document Type 10-Q  
Amendment Flag false  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2019  
Entity Central Index Key 0000924901  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity File Number 1-13274  
Entity Incorporation, State or Country Code MD  
Entity Tax Identification Number 22-3305147  
Entity Address, Address Line One Harborside 3, 210 Hudson St., Ste. 400  
Entity Address, City or Town Jersey City  
Entity Address, State or Province NJ  
Entity Address, Postal Zip Code 07311  
City Area Code 732  
Local Phone Number 590-1010  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Trading Symbol CLI  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   90,553,752
Mack-Cali Realty LP [Member]    
Entity Registrant Name Mack-Cali Realty, L.P.  
Entity Central Index Key 0001067063  
Entity File Number 333-57103  
Entity Filer Category Large Accelerated Filer