Annual report pursuant to Section 13 and 15(d)

Commitments And Contingencies (Other) (Narrative) (Details)

v2.4.1.9
Commitments And Contingencies (Other) (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended 24 Months Ended
Dec. 31, 2014
property
Dec. 31, 2016
Jul. 31, 2012
sqft
Commitments And Contingencies [Line Items]      
Percentage of interest in venture    [1]    
Property Lock-Ups [Member]      
Commitments And Contingencies [Line Items]      
Number of properties 7us-gaap_NumberOfRealEstateProperties
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= cli_PropertyLockUpsMember 		   
Properties aggregate net book value $ 125.3cli_PropertyNetBookValue
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= cli_PropertyLockUpsMember 		   
Expiration year 2016    
Property Lock-Ups Expired [Member]      
Commitments And Contingencies [Line Items]      
Number of properties 110us-gaap_NumberOfRealEstateProperties
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= cli_PropertyLockUpsExpiredMember 		   
Properties aggregate net book value 1,300.0cli_PropertyNetBookValue
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= cli_PropertyLockUpsExpiredMember 		   
Wegmans Food Markets, Inc. [Member]      
Commitments And Contingencies [Line Items]      
Costs of the project incurred 8.0cli_ConstructionAndDevelopmentCostsIncurred
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_WegmansFoodMarketsIncMember 		   
Delivery date to tenant late 2016    
Area of property (in square feet)     140,000us-gaap_AreaOfRealEstateProperty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_WegmansFoodMarketsIncMember
Wegmans Food Markets, Inc. [Member] | Scenario, Forecast [Member]      
Commitments And Contingencies [Line Items]      
Total project costs   $ 25.3cli_EstimatedCostOfProject
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_WegmansFoodMarketsIncMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember 		 
[1] Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.