Quarterly report pursuant to Section 13 or 15(d)

Commitments And Contingencies (Changes In Executive Officers) (Narrative) (Details)

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Commitments And Contingencies (Changes In Executive Officers) (Narrative) (Details) - USD ($)
 3 Months Ended 6 Months Ended
Jun. 05, 2018
Jun. 30, 2018
Mar. 31, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Commitments And Contingencies [Line Items]              
General and administrative   $ 13,455,000   $ 12,491,000 $ 29,540,000 $ 24,083,000  
Accounts payable, accrued expenses and other liabilities   180,941,000     180,941,000   $ 192,716,000
Restructuring costs related to stock compensation     $ 600,000   $ 600,000    
Shares granted         40,185    
Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
General and administrative   13,455,000   $ 12,491,000 $ 29,540,000 $ 24,083,000  
Accounts payable, accrued expenses and other liabilities   180,941,000     180,941,000   $ 192,716,000
Messr Rudin [Member]              
Commitments And Contingencies [Line Items]              
Severance benefits         $ 2,558,082    
Period for continuation of health insurance         18 months    
Payment to former executive officers   1,200,000          
Payment of unreimbursed expenses         $ 50,000    
COBRA payment   34,047     34,047    
Accounts payable, accrued expenses and other liabilities   2,700,000     2,700,000    
Restructuring costs related to stock compensation   1,600,000          
Messr Krug [Member]              
Commitments And Contingencies [Line Items]              
Severance benefits         1,312,500    
Prorated 2018 target bonus amount   93,750     $ 93,750    
Messr Krug [Member] | Maximum [Member]              
Commitments And Contingencies [Line Items]              
Period for continuation of health insurance         2 years    
COBRA payment   42,000     $ 42,000    
Messr DeLorenzo [Member]              
Commitments And Contingencies [Line Items]              
Severance benefits         $ 500,000    
Period for continuation of health insurance         18 months    
Messr DeLorenzo [Member] | Maximum [Member]              
Commitments And Contingencies [Line Items]              
COBRA payment   42,000     $ 42,000    
Messrs. Rudin, Krug, And DeLorenzo [Member] | Employee Severance [Member]              
Commitments And Contingencies [Line Items]              
General and administrative     $ 2,700,000        
Accounts payable, accrued expenses and other liabilities   $ 100,000     $ 100,000    
Time-Based Award [Member] | Messr Rudin [Member] | Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
Shares granted 32,311            
Time-Based Award [Member] | Messr Krug [Member] | Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
Accelerated vesting shares         13,306    
Time-Based Award [Member] | Messr DeLorenzo [Member] | Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
Partial accelerated vesting shares         9,111    
Performance Shares [Member] | Messr Rudin [Member] | Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
Shares granted 175,127            
Performance Shares [Member] | Messr Krug [Member] | Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
Accelerated vesting shares         18,665    
Performance Shares [Member] | Messr DeLorenzo [Member] | Mack-Cali Realty LP [Member]              
Commitments And Contingencies [Line Items]              
Partial accelerated vesting shares         13,982