Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2017
Feb. 16, 2018
Jun. 30, 2017
Entity Registrant Name MACK CALI REALTY CORP    
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2017    
Entity Central Index Key 0000924901    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Entity Current Reporting Status Yes    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Public Float     $ 2,424,863,956
Entity Common Stock, Shares Outstanding   90,139,823  
Mack-Cali Realty LP [Member]      
Entity Registrant Name MACK CALI REALTY LP    
Entity Central Index Key 0001067063    
Entity Filer Category Large Accelerated Filer