Annual report pursuant to Section 13 and 15(d)

Redeemable Noncontrolling Interests (Narrative) (Details)

v3.8.0.1
Redeemable Noncontrolling Interests (Narrative) (Details) - USD ($)
 12 Months Ended
Mar. 10, 2017
Feb. 28, 2017
Feb. 27, 2017
Feb. 03, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Apr. 30, 2017
Redeemable Noncontrolling Interest [Line Items]                
Expiration period         10 years      
Minimum [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Percentage of interest in venture         12.50%      
Maximum [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Percentage of interest in venture         85.00%      
Mack-Cali Realty LP [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Common unit distribution per unit declared         $ 0.75 $ 0.60 $ 0.60  
Rockpoint [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Pro rata distribution         10.90%      
Estimated redemption value         $ 223,000,000      
RRT [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Pro rata distribution         89.10%      
Series A Units [Member] | Mack-Cali Realty LP [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Preferred units aggregate amount       $ 42,800,000        
Preferred stock shares issued       42,800        
Preferred units shares issued       42,800        
Preferred unit annual rate       3.50%        
Percentage of interest in venture       37.50%        
Preferred unit in operating partnership       $ 1,000        
Convertible preferred units       28.15        
Expiration period       5 years        
Shares converted to common units       1,204,820        
Common unit distribution per unit declared       $ 35.52        
Series A-1 Units [Member] | Mack-Cali Realty LP [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Preferred stock shares issued   9,213            
Preferred units shares issued   9,213           91
Preferred unit annual rate   3.50%            
Percentage of interest in venture   13.80%            
Preferred unit in operating partnership   $ 1,000            
Convertible preferred units   27.936            
Expiration period   5 years            
Shares converted to common units   257,375            
Common unit distribution per unit declared   $ 35.80            
Monaco [Member] | Series A-1 Units [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Percentage of interest in venture   13.80%            
Monaco [Member] | Series A-1 Units [Member] | Mack-Cali Realty LP [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Preferred units aggregate amount   $ 9,100,000            
Preferred units shares issued   9,122           91
Percentage of interest in venture               71.20%
Investment Agreement [Member] | Rockpoint [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Contributed equity value $ 1,230,000,000              
Incremental closing payments, Limited Partnership interest $ 150,000,000              
Investment Agreement [Member] | Rockpoint [Member] | Minimum [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Incremental closing payments, Limited Partnership interest         $ 10,000,000      
Investment Agreement [Member] | Rockpoint [Member] | Maximum [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Contributed amount to obtain equity units     $ 300,000,000          
RRLP [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Annual return on the equity value         6.00%      
RRLP [Member] | Rockpoint [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Annual return         6.00%      
Base return         5.00%      
Internal rate of return         11.00%      
Pro rata share         50.00%      
RRLP [Member] | RRT [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Base return         95.00%      
Participation Rights [Member] | Maximum [Member]                
Redeemable Noncontrolling Interest [Line Items]                
Contributed amount to obtain equity units         $ 200,000,000