Quarterly report pursuant to Section 13 or 15(d)

Redeemable Noncontrolling Interests (Narrative) (Details)

v3.20.2
Redeemable Noncontrolling Interests (Narrative) (Details)
 3 Months Ended 6 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. 30, 2020
USD ($)
Jun. 30, 2019
USD ($)
Mar. 31, 2019
USD ($)
Jun. 30, 2020
USD ($)
Jun. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Apr. 30, 2017
shares
Redeemable Noncontrolling Interest [Line Items]                              
General and administrative               $ 17,242,000 $ 16,946,000   $ 33,060,000 $ 30,265,000      
Expiration period                     10 years        
Minimum [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Percentage of interest in venture               20.00%     20.00%        
Maximum [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Percentage of interest in venture               85.00%     85.00%        
Mack-Cali Realty LP [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
General and administrative               $ 17,242,000 $ 16,946,000   $ 33,060,000 30,265,000      
Series A Units [Member] | Mack-Cali Realty LP [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
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 that may be 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 units shares issued | shares         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 | shares         27.936                    
Expiration period         5 years           5 years        
Shares that may be converted to common units | shares         257,375                    
Common unit distribution per unit declared | $ / shares         $ 35.80                    
Monaco [Member] | Series A-1 Units [Member] | Mack-Cali Realty LP [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Preferred units shares issued | shares         9,122                    
Investment Agreement [Member] | Minimum [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Incremental closing payments, Limited Partnership interest                           $ 105,000,000  
Add On Investment Agreement [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] | Investment Agreement [Member] | Cash Flow From Capital Events, Distribution Four [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Capital base return                     5.00%        
RRLP [Member] | Credit Enhancement Note [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Maximum borrowing capacity               50,000,000     $ 50,000,000        
Increased line of credit               25,000,000     $ 25,000,000        
Spread over LIBOR                     50.00%        
Rockpoint [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Estimated redemption value                     $ 481,000,000        
Rockpoint [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Invested capital               400,000,000     400,000,000        
Rockpoint [Member] | Cash Flow From Capital Events, Distribution Five [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Invested capital               400,000,000     400,000,000        
Rockpoint [Member] | Cash Flow From Capital Events, Distribution Six [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Invested capital               $ 400,000,000     $ 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                          
Rockpoint [Member] | Preferred Units [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     10.947%        
Rockpoint [Member] | Preferred Units [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     21.89%        
Rockpoint [Member] | Preferred Units [Member] | Cash Flow From Capital Events, Distribution Five [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     21.89%        
Rockpoint [Member] | Investment Agreement [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           $ 45,000,000   $ 45,000,000   $ 105,000,000  
Rockpoint [Member] | Investment Agreement [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          
Rockpoint [Member] | Add On Investment Agreement [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                   $ 100,000,000        
General and administrative                         $ 371,000    
Rockpoint [Member] | Add On Investment Agreement [Member] | Maximum [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Contributed amount to obtain equity units                     $ 154,000,000        
Rockpoint [Member] | RRLP [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Annual return                     6.00%        
Base return                     4.64%        
Rockpoint [Member] | RRLP [Member] | Cash Flow From Capital Events, Distribution Three [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     4.64%        
Rockpoint [Member] | RRLP [Member] | Cash Flow From Capital Events, Distribution Four [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Capital base return                     4.64%        
Rockpoint [Member] | RRLP [Member] | Cash Flow From Capital Events, Distribution Five [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Internal rate of return                     11.00%        
Rockpoint [Member] | RRLP [Member] | Cash Flow From Capital Events, Distribution Six [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata share                     50.00%        
Rockpoint [Member] | RRLP [Member] | Investment Agreement [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     5.00%        
Rockpoint [Member] | RRLP [Member] | Investment Agreement [Member] | Cash Flow From Capital Events, Distribution Three [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     95.00%        
RRT [Member] | Preferred Units [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     2.65%        
RRT [Member] | Preferred Units [Member] | Cash Flow From Capital Events, Distribution Five [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     2.65%        
RRT [Member] | Preferred Units [Member] | Cash Flow From Capital Events, Distribution Six [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     1.325%        
RRT [Member] | Common Units [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     75.46%        
RRT [Member] | Common Units [Member] | Cash Flow From Capital Events, Distribution Five [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     75.46%        
RRT [Member] | Common Units [Member] | Cash Flow From Capital Events, Distribution Six [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Pro rata distribution                     87.728%        
RRT [Member] | RRLP [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Loan-to-value ratio     65.00%                        
Equity capitalization percent                     10.00%        
RRT [Member] | RRLP [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     95.36%        
RRT [Member] | RRLP [Member] | Cash Flow From Capital Events, Distribution Three [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     95.36%        
RRT [Member] | RRLP [Member] | Cash Flow From Capital Events, Distribution Four [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Capital base return                     95.36%        
RRT [Member] | RRLP [Member] | Investment Agreement [Member] | Cash Flow From Operations [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     95.00%        
RRT [Member] | RRLP [Member] | Investment Agreement [Member] | Cash Flow From Capital Events, Distribution Three [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Base return                     5.00%        
RRT [Member] | RRLP [Member] | Investment Agreement [Member] | Cash Flow From Capital Events, Distribution Four [Member]                              
Redeemable Noncontrolling Interest [Line Items]                              
Capital base return                     95.00%