Annual report pursuant to Section 13 and 15(d)

Commitments And Contingencies (Roseland Contingent Consideration) (Narrative) (Details)

v2.4.1.9
Commitments And Contingencies (Roseland Contingent Consideration) (Narrative) (Details) (USD $)
3 Months Ended 12 Months Ended 0 Months Ended 1 Months Ended 0 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Sep. 17, 2014
Mar. 21, 2014
Jan. 25, 2013
Apr. 30, 2013
Jul. 18, 2014
Oct. 23, 2012
Business Acquisition, Contingent Consideration [Line Items]                                  
Interest and other investment income $ 1,399,000us-gaap_InvestmentIncomeInterestAndDividend $ 908,000us-gaap_InvestmentIncomeInterestAndDividend $ 922,000us-gaap_InvestmentIncomeInterestAndDividend $ 386,000us-gaap_InvestmentIncomeInterestAndDividend $ 1,616,000us-gaap_InvestmentIncomeInterestAndDividend $ 187,000us-gaap_InvestmentIncomeInterestAndDividend $ 1,094,000us-gaap_InvestmentIncomeInterestAndDividend $ 6,000us-gaap_InvestmentIncomeInterestAndDividend $ 3,615,000us-gaap_InvestmentIncomeInterestAndDividend $ 2,903,000us-gaap_InvestmentIncomeInterestAndDividend $ 34,000us-gaap_InvestmentIncomeInterestAndDividend            
Earn out paid                 5,228,000cli_BusinessAcquisitionContingentConsiderationCashPaid 2,755,000cli_BusinessAcquisitionContingentConsiderationCashPaid              
Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Fair value of contingent consideration 900,000us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
              900,000us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
              10,000,000us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
Business acquisition, contingent cash payment                                 15,600,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
Interest and other investment income                 1,500,000us-gaap_InvestmentIncomeInterestAndDividend
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
2,300,000us-gaap_InvestmentIncomeInterestAndDividend
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
             
Purchase accounting adjustments                 0us-gaap_GoodwillPurchaseAccountingAdjustments
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
               
Earn out paid                       1,400,000cli_BusinessAcquisitionContingentConsiderationCashPaid
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
1,400,000cli_BusinessAcquisitionContingentConsiderationCashPaid
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
2,800,000cli_BusinessAcquisitionContingentConsiderationCashPaid
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
     
Contingent purchase price measurement period                 33 months                
Amount of cash deposited to escrow                 34,000,000cli_BusinessAcquisitionAcquireeCashDepositedToEscrow
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
               
Amount of escrow released                             6,700,000cli_BusinessAcquisitionAcquireeAmountOfEscrowReleased
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
   
Roseland Assets [Member] | Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Fair value of contingent consideration                                 6,300,000us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_RoselandAssetsMember
Business acquisition, contingent cash payment                                 8,600,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_RoselandAssetsMember
Completion Of Certain Developments [Member] | Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Business acquisition, contingent cash payment                                 2,800,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_CompletionOfCertainDevelopmentsMember
Start Of Construction On Certain Developments [Member] | Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Business acquisition, contingent cash payment                                 2,800,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_StartOfConstructionOnCertainDevelopmentsMember
Completion/Start Of Certain Developments [Member] | Minimum [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Probability of occurrence 92.00%cli_ProbabilityOfOccurrence
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_CompletionStartOfCertainDevelopmentsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
              92.00%cli_ProbabilityOfOccurrence
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_CompletionStartOfCertainDevelopmentsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
               
Completion/Start Of Certain Developments [Member] | Maximum [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Probability of occurrence 99.00%cli_ProbabilityOfOccurrence
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_CompletionStartOfCertainDevelopmentsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
              99.00%cli_ProbabilityOfOccurrence
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_CompletionStartOfCertainDevelopmentsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
               
Obtaining Of Tax Credits/Grants [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Probability of occurrence 50.00%cli_ProbabilityOfOccurrence
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
              50.00%cli_ProbabilityOfOccurrence
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
               
Obtaining Of Tax Credits/Grants [Member] | Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Business acquisition, contingent cash payment 3,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
              3,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
              3,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
Business acquisition, earn out period                 3 years                
Earn out paid                               1,000,000cli_BusinessAcquisitionContingentConsiderationCashPaid
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
 
Obtaining Of Tax Credits/Grants [Member] | Roseland Partners, L.L.C. [Member] | Scenario, Forecast [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Earn out paid                 1,000,000cli_BusinessAcquisitionContingentConsiderationCashPaid
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
               
Total Return To Shareholders [Member] | Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Fair value of contingent consideration                                 3,700,000us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_TotalReturnToShareholdersMember
Business acquisition, contingent cash payment 7,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_TotalReturnToShareholdersMember
              7,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_TotalReturnToShareholdersMember
               
Business acquisition, earn out period                 3 years                
Failure To Achieve Certain Level Of Fee Revenue [Member] | Roseland Partners, L.L.C. [Member]                                  
Business Acquisition, Contingent Consideration [Line Items]                                  
Business acquisition, contingent cash payment $ 2,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_FailureToAchieveCertainLevelOfFeeRevenueMember
              $ 2,000,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_FailureToAchieveCertainLevelOfFeeRevenueMember