Mack-Cali Realty Corporation Stockholders' Equity And Mack-Cali Realty, L.P.'s Partners' Capital (Restricted Stock Awards And Performance Share Units) (Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Jun. 05, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Unvested performance shares         42,000
Unvested restricted stock outstanding   145,278 136,220 346,946 153,560
Shares granted   74,622 41,337 [1] 376,719 [2],[3],[4]  
Messr Hersh [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Unvested performance shares         126,000
Restricted Stock [Member] | 2013 Incentive Stock Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock compensation vesting period   3 years      
Shares granted 37,550.54        
Restricted Stock [Member] | Minimum [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock compensation vesting period   1 year      
Restricted Stock [Member] | Maximum [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock compensation vesting period   7 years      
Unvested Restricted Stock [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Unvested restricted stock outstanding   120,245 98,669 136,946  
Total Stockholder Return Based Awards [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Total unrecognized compensation cost   $ 1.1      
Total unrecognized compensation cost, period of recognition   2 years 4 months 24 days      
Performance Shares [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Total unrecognized compensation cost   $ 0.7      
Total unrecognized compensation cost, period of recognition   1 year 4 months 24 days      
Performance Shares [Member] | 2013 Incentive Stock Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares granted 112,651.64        
Performance period   3 years      
Performance Shares [Member] | Minimum [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Percentage of shares vested 0.00%        
Performance Shares [Member] | Maximum [Member] | 2013 Incentive Stock Plan [Member] | Three Years Period Award [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Percentage of shares vested 150.00%        
[1] Included in the 41,337 Restricted Stock Awards granted in 2015 were 37,551 awards granted to the Company's two executive officers, Mitchell E. Rudin and Michael J. DeMarco.
[2] Included in the 376,719 Restricted Stock Awards granted in 2014 were 8,211 awards granted to the Company's two executive officers, Anthony Krug and Gary Wagner.
[3] Includes 126,000 Performance Shares which were legally granted in 2013 for which future performance goals had not yet been set by the Committee. These awards were not considered granted for accounting purposes until these goals are set. These were considered granted in 2014 for accounting purposes in connection with the announcement of the departure of Mitchell E. Hersh in the fourth quarter 2014.
[4] Includes 42,000 Performance Shares which were legally granted in 2013 for which the 2014 performance goals were set by the Committee on March 31, 2014. Also includes 87,734 shares which were additionally considered granted for accounting purposes to two executive officers in connection with their departure effective March 31, 2014, which vested on April 1, 2014.