Discontinued Operations (Tables)  | 
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| Summary Of Income From Discontinued Operations, Includes Realized Gains (Losses) And Unrealized Losses | 
 
 (a)Represents valuation allowances and impairment charges on properties classified as discontinued operations in 2020. (b)See Note 3: Real Estate Transactions – Dispositions for further information regarding properties sold and related gains (losses). 
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| Mack-Cali Realty LP [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Summary Of Income From Discontinued Operations, Includes Realized Gains (Losses) And Unrealized Losses | 
 
 (a)Represents valuation allowances and impairment charges on properties classified as discontinued operations in 2020. (b)See Note 3: Real Estate Transactions – Dispositions for further information regarding properties sold and related gains (losses). 
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- Definition Schedule Of Disposal Groups Including Discontinued Operations Income Statement Balance Sheet And Additional Disclosures Includes Disposition Of Rental Property And Impairments [Table Text Block] No definition available. 
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- Details 
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