Annual report pursuant to Section 13 and 15(d)

Noncontrolling Interests In Subsidiaries (Narrative) (Details)

v2.4.1.9
Noncontrolling Interests In Subsidiaries (Narrative) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Noncontrolling Interest [Line Items]    
Number of common shares received upon redemption of common units 1cli_NumberOfCommonSharesReceivedUponRedemptionOfCommonUnits  
Rebalance of ownership percentage $ 0.6cli_RebalanceOfOwnershipPercentage  
Percentage of noncontrolling interest 11.10%us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners 11.90%us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Internal rate of return 9.00%cli_InternalRateOfReturn  
Participation Rights [Member]    
Noncontrolling Interest [Line Items]    
Number of properties 3us-gaap_NumberOfRealEstateProperties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_ParticipationRightsMember 		 
Excess net cash flow remaining after the distribution to the Company 50.00%cli_DistributionOfCashFlowToIndividualCompaniesPercentage
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_ParticipationRightsMember 		 
Internal rate of return 10.00%cli_InternalRateOfReturn
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_ParticipationRightsMember 		 
Future Developments [Member] | Participation Rights [Member]    
Noncontrolling Interest [Line Items]    
Number of properties 1us-gaap_NumberOfRealEstateProperties
/ us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis
= cli_FutureDevelopmentsMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= cli_ParticipationRightsMember