Quarterly report pursuant to Section 13 or 15(d)

Redeemable Noncontrolling Interests (Narrative) (Details)

v3.10.0.1
Redeemable Noncontrolling Interests (Narrative) (Details) - USD ($)
 6 Months Ended
Mar. 10, 2017
Feb. 28, 2017
Feb. 27, 2017
Feb. 03, 2017
Jun. 30, 2018
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%  
Rockpoint [Member]            
Redeemable Noncontrolling Interest [Line Items]            
Pro rata distribution         14.90%  
Estimated redemption value         $ 292,000,000  
Invested capital         $ 215,000,000  
RRT [Member]            
Redeemable Noncontrolling Interest [Line Items]            
Pro rata distribution         85.10%  
Series A Units [Member] | Mack-Cali Realty LP [Member]            
Redeemable Noncontrolling Interest [Line Items]            
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 that may be 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 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 that may be converted to common units   257,375        
Common unit distribution per unit declared   $ 35.80        
Monaco [Member] | Series A-1 Units [Member] | Mack-Cali Realty LP [Member]            
Redeemable Noncontrolling Interest [Line Items]            
Preferred units shares issued   9,122        
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       $ 65,000,000  
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