Quarterly report pursuant to Section 13 or 15(d)

Commitments And Contingencies (Tax Abatement Agreements) (Narrative) (Details)

v2.4.1.9
Commitments And Contingencies (Tax Abatement Agreements) (Narrative) (Details) (USD $)
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Harborside Financial Center Plaza 4-A [Member]    
Commitments And Contingencies [Line Items]    
Project period 20 years  
Percentage of PILOT on project costs 2.00%cli_PaymentsInLieuOfPropertyTaxAsPercentageOfTotalProjectCost
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFouraMember 		 
Total project costs $ 49,500,000cli_EstimatedCostOfProject
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFouraMember 		 
Payments in lieu of property taxes (PILOT) 247,000cli_PaymentsInLieuOfPropertyTaxes
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFouraMember 		247,000cli_PaymentsInLieuOfPropertyTaxes
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFouraMember
Harborside Financial Center Plaza 5 [Member]    
Commitments And Contingencies [Line Items]    
Project period 20 years  
Percentage of PILOT on project costs 2.00%cli_PaymentsInLieuOfPropertyTaxAsPercentageOfTotalProjectCost
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFiveMember 		 
Total project costs 170,900,000cli_EstimatedCostOfProject
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFiveMember 		 
Payments in lieu of property taxes (PILOT) $ 854,000cli_PaymentsInLieuOfPropertyTaxes
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFiveMember 		$ 854,000cli_PaymentsInLieuOfPropertyTaxes
/ us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis
= cli_HarborsideFinancialCenterPlazaFiveMember
Port Imperial South 4/5 Garage [Member]    
Commitments And Contingencies [Line Items]    
Project period 5 years  
Period of real estate taxes phase in 5 years  
Park Square [Member]    
Commitments And Contingencies [Line Items]    
Period of partial abatement of real estate taxes 4 years