Annual report pursuant to Section 13 and 15(d)

Unsecured Revolving Credit Facility And Term Loans (Schedule Of Interest Rates On Outstanding Borrowings, Alternate Base Rate Loans, And Facility Fee) (Details)

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Unsecured Revolving Credit Facility And Term Loans (Schedule Of Interest Rates On Outstanding Borrowings, Alternate Base Rate Loans, And Facility Fee) (Details) - 2017 Credit Facility [Member]
 12 Months Ended
Dec. 31, 2017
Line of Credit Facility [Line Items]  
Interest Rate - Applicable Basis Points Above LIBOR 1.20%
Facility Fee Basis Points 0.25%
Mack-Cali Realty LP [Member] | No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]  
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR 1.55%
Facility Fee Basis Points 0.30%
Mack-Cali Realty LP [Member] | Baa3 [Member] | BBB- [Member]  
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings BBB- or Baa3 (current interest rate based on Company's election)
Interest Rate - Applicable Basis Points Above LIBOR 1.20%
Facility Fee Basis Points 0.25%
Mack-Cali Realty LP [Member] | Baa2 [Member] | BBB [Member]  
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings BBB or Baa2
Interest Rate - Applicable Basis Points Above LIBOR 1.00%
Facility Fee Basis Points 0.20%
Mack-Cali Realty LP [Member] | Baa1 [Member] | BBB+ [Member]  
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings BBB+ or Baa1
Interest Rate - Applicable Basis Points Above LIBOR 0.90%
Facility Fee Basis Points 0.15%
Mack-Cali Realty LP [Member] | A3 Or Higher [Member] | A- Or Higher [Member]  
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings A- or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR 0.875%
Facility Fee Basis Points 0.125%
Mack-Cali Realty LP [Member] | Base Rate [Member] | No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]  
Line of Credit Facility [Line Items]  
Interest Rate - Applicable Basis Points Above LIBOR 0.55%
Mack-Cali Realty LP [Member] | Base Rate [Member] | Baa3 [Member] | BBB- [Member]  
Line of Credit Facility [Line Items]  
Interest Rate - Applicable Basis Points Above LIBOR 0.20%
Mack-Cali Realty LP [Member] | Base Rate [Member] | Baa2 [Member] | BBB [Member]  
Line of Credit Facility [Line Items]  
Interest Rate - Applicable Basis Points Above LIBOR 0.00%
Mack-Cali Realty LP [Member] | Base Rate [Member] | Baa1 [Member] | BBB+ [Member]  
Line of Credit Facility [Line Items]  
Interest Rate - Applicable Basis Points Above LIBOR 0.00%
Mack-Cali Realty LP [Member] | Base Rate [Member] | A3 Or Higher [Member] | A- Or Higher [Member]  
Line of Credit Facility [Line Items]  
Interest Rate - Applicable Basis Points Above LIBOR 0.00%