Annual report pursuant to Section 13 and 15(d)

Redeemable Noncontrolling Interests (Narrative) (Details)

v3.19.3.a.u2
Redeemable Noncontrolling Interests (Narrative) (Details)
 3 Months Ended 12 Months Ended
Jun. 30, 2019
USD ($)
Jun. 28, 2019
USD ($)
Jun. 26, 2019
USD ($)
property
Mar. 10, 2017
USD ($)
Feb. 28, 2017
USD ($)
$ / shares
shares
Feb. 27, 2017
USD ($)
Feb. 03, 2017
USD ($)
$ / shares
shares
Jun. 26, 2016
USD ($)
Jun. 30, 2019
Mar. 31, 2019
USD ($)
Dec. 31, 2019
USD ($)
$ / shares
Dec. 31, 2018
USD ($)
$ / shares
Dec. 31, 2017
USD ($)
$ / shares
Apr. 30, 2017
shares
Redeemable Noncontrolling Interest [Line Items]                            
General and administrative                     $ 57,535,000 $ 53,865,000 $ 50,475,000  
Expiration period                     10 years      
Minimum [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Percentage of interest in venture                     20.00%      
Maximum [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Percentage of interest in venture                     85.00%      
Mack-Cali Realty LP [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
General and administrative                     $ 57,535,000 $ 53,865,000 $ 50,475,000  
Common unit distribution per unit declared | $ / shares                     $ 0.80 $ 0.80 $ 0.75  
Rockpoint [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Estimated redemption value                     $ 490,000,000      
Rockpoint [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Invested capital                     400,000,000      
Rockpoint [Member] | Cash Flow From Capital Events, Distribution Five [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Invested capital                     400,000,000      
Rockpoint [Member] | Cash Flow From Capital Events, Distribution Six [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Invested capital                     $ 400,000,000      
Rockpoint [Member] | Distribution One [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Purchase price     $ 173,500,000                      
Purchase price, less distributions   $ 198,500,000                        
Rockpoint [Member] | Distribution Two [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Purchase price, less distributions   $ 1,500,000                        
Series A Units [Member] | Mack-Cali Realty LP [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Preferred stock shares issued | shares             42,800              
Preferred units shares issued | shares             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 | shares             28.15              
Expiration period             5 years              
Shares converted to common units | shares             1,204,820              
Common unit distribution per unit declared | $ / shares             $ 35.52              
Series A-1 Units [Member] | Mack-Cali Realty LP [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Preferred stock shares issued | shares         9,213                  
Preferred units shares issued | shares                           91
Preferred unit annual rate         3.50%                  
Percentage of interest in venture         13.80%                  
Preferred unit in operating partnership         $ 1,000                  
Convertible preferred units | shares         27.936                  
Expiration period         5 years           5 years      
Shares converted to common units | shares         257,375                  
Common unit distribution per unit declared | $ / shares         $ 35.80                  
Preferred Units [Member] | Rockpoint [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     21.89%      
Preferred Units [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Five [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     21.89%      
Preferred Units [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Six [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     10.947%      
Preferred Units [Member] | RRT [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     2.65%      
Preferred Units [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Five [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     2.65%      
Preferred Units [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Six [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     1.325%      
Monaco [Member] | Series A-1 Units [Member] | Mack-Cali Realty LP [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Preferred units shares issued | shares         9,122                  
Common Units [Member] | RRT [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     75.46%      
Common Units [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Five [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     75.46%      
Common Units [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Six [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata distribution                     87.728%      
Investment Agreement [Member] | Rockpoint [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Contributed equity value       $ 1,230,000,000                    
Incremental closing payments, Limited Partnership interest     46,000,000 $ 150,000,000       $ 46,000,000   $ 45,000,000   $ 105,000,000    
Contributed amount to obtain equity units                   300,000,000        
Investment Agreement [Member] | Rockpoint [Member] | Maximum [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Contributed amount to obtain equity units           $ 300,000,000                
Contributed amount to obtain equity units           $ 300,000,000       $ 300,000,000        
Add On Investment Agreement [Member] | Rockpoint [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Contributed amount to obtain equity units     $ 100,000,000                      
Number of properties in which additional interest was acquired during period | property     2                      
Right of first refusal to invest $ 100,000,000                          
General and administrative                     $ 371,000      
Add On Investment Agreement [Member] | Rockpoint [Member] | Maximum [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Contributed amount to obtain equity units $ 154,000,000                          
RRLP [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Annual return on the equity value                     6.00%      
RRLP [Member] | Rockpoint [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Annual return                     6.00%      
Base return                     4.64%      
RRLP [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Three [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                     4.64%      
RRLP [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Four [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Capital base return                     4.64%      
RRLP [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Five [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Internal rate of return                     11.00%      
RRLP [Member] | RRT [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Loan-to-value ratio     65.00%                      
Equity capitalization percent                     10.00%      
RRLP [Member] | RRT [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                     95.36%      
RRLP [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Three [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                     95.36%      
RRLP [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Four [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Capital base return                     95.36%      
RRLP [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Six [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Pro rata share                     50.00%      
RRLP [Member] | Investment Agreement [Member] | Rockpoint [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                 5.00%          
RRLP [Member] | Investment Agreement [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Three [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                 5.00%          
RRLP [Member] | Investment Agreement [Member] | Rockpoint [Member] | Cash Flow From Capital Events, Distribution Four [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Capital base return                     5.00%      
RRLP [Member] | Investment Agreement [Member] | RRT [Member] | Cash Flow From Operations [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                 95.00%          
RRLP [Member] | Investment Agreement [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Three [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Base return                 95.00%          
RRLP [Member] | Investment Agreement [Member] | RRT [Member] | Cash Flow From Capital Events, Distribution Four [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Capital base return                     95.00%      
RRLP [Member] | Credit Enhancement Note [Member]                            
Redeemable Noncontrolling Interest [Line Items]                            
Maximum borrowing capacity                     $ 50,000,000      
Increased line of credit                     $ 25,000,000      
Spread over LIBOR                     50.00%