Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies (Narrative) (Details)

v3.19.3
Significant Accounting Policies (Narrative) (Details) - USD ($)
 3 Months Ended 9 Months Ended 12 Months Ended
Jan. 01, 2019
Sep. 30, 2019
Dec. 31, 2018
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2017
Oct. 04, 2019
Jun. 30, 2019
Jan. 03, 2019
Jun. 30, 2018
Significant Accounting Policies [Line Items]                      
Capitalized development and construction salaries and other related costs   $ 500,000   $ 600,000 $ 1,600,000 $ 1,700,000          
Maximum period after cessation of major construction activity that projects are considered complete         1 year            
Threshold of investment value for discontinuation of equity method accounting   0     $ 0            
Amortization of deferred financing costs   1,121,000   1,302,000 3,478,000 3,543,000          
Loss from extinguishment of debt, net         1,801,000 (10,289,000)          
Write-off of unamortized deferred financing costs   285,000   285,000 105,000          
Deferred leasing costs       $ 598,000   $ 2,226,000          
Leasing personnel costs   534,000     1,818,000            
Deferred tax asset   $ 9,500,000     9,500,000   $ 5,300,000        
Income taxes, material adjustment amount         $ 0            
Common stock, shares outstanding   90,551,967 90,320,306   90,551,967         90,320,408  
Common units outstanding   9,973,344 10,229,349 10,241,849 9,973,344 10,241,849 10,438,855   9,976,344 10,174,285 10,266,143
LTIP units outstanding   1,826,331 1,707,106 1,766,320 1,826,331 1,766,320 1,230,877   1,826,331 1,762,170 1,795,747
Distributions payable, record date     Jan. 03, 2019   Oct. 04, 2019            
Distributions payable, approved date     Dec. 11, 2018   Sep. 24, 2019            
Common stock dividends and common unit distributions per share   $ 0.20 $ 0.20                
Stock compensation expense   $ 1,980,000   $ 1,770,000 $ 6,051,000 $ 4,959,000          
Distributions payable, pay date     Jan. 11, 2019   Oct. 11, 2019            
Increase (decrease) to valuation allowance             $ (5,300,000)        
Federal income tax rate         21.00%            
Gain (loss) from extinguishment of debt, net   (98,000)   0 $ 1,801,000 (10,289,000)          
Common stock dividends   (18,106,000)   (18,056,000) (54,282,000) (54,136,000)          
Common unit distributions   (2,360,000)   (2,364,000) (6,417,000) (6,760,000)          
General Partner Common Unitholders [Member]                      
Significant Accounting Policies [Line Items]                      
Common unit distributions   (18,106,000)   (18,056,000) (54,282,000) (54,136,000)          
Accounting Standards Update 2017-12 [Member]                      
Significant Accounting Policies [Line Items]                      
Adjustment to retained earnings $ 400,000                    
Subsequent Event [Member]                      
Significant Accounting Policies [Line Items]                      
Common stock, shares outstanding               90,552,178      
Common units outstanding               9,850,074      
LTIP units outstanding               1,949,601      
Mack-Cali Realty LP [Member]                      
Significant Accounting Policies [Line Items]                      
Loss from extinguishment of debt, net         1,801,000 (10,289,000)          
Leasing personnel costs   534,000     1,818,000            
Gain (loss) from extinguishment of debt, net   (98,000)     1,801,000 (10,289,000)          
Common unit distributions   (20,466,000)   (20,420,000) (60,699,000) (60,896,000)          
LTIP value     $ 400,000                
Dividends paid   400,000 18,100,000                
Mack-Cali Realty LP [Member] | General Partner Common Unitholders [Member]                      
Significant Accounting Policies [Line Items]                      
Common unit distributions   (18,106,000)   (18,056,000) (54,282,000) (54,136,000)          
Dividends paid   18,100,000                  
Mack-Cali Realty LP [Member] | Limited Partner Common Unitholders [Member]                      
Significant Accounting Policies [Line Items]                      
Common unit distributions   (2,360,000)   $ (2,364,000) $ (6,417,000) $ (6,760,000)          
Common Units [Member] | Mack-Cali Realty LP [Member] | Limited Partner Common Unitholders [Member]                      
Significant Accounting Policies [Line Items]                      
Dividends paid   $ 2,000,000.0 $ 2,000,000.0