Annual report pursuant to Section 13 and 15(d)

Commitments And Contingencies (Roseland Transaction Modifications) (Narrative) (Details)

v2.4.1.9
Commitments And Contingencies (Roseland Transaction Modifications) (Narrative) (Details) (USD $)
 3 Months Ended 12 Months Ended 0 Months Ended 12 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
Oct. 23, 2015
item
Apr. 24, 2015
Oct. 28, 2014
Jul. 18, 2014
Oct. 23, 2012
Commitments And Contingencies [Line Items]                                      
Severance benefits                 $ 23,800,000us-gaap_SeveranceCosts1                    
Percentage of interest in venture    [1]                  [1]                    
Earn out paid                 5,228,000cli_BusinessAcquisitionContingentConsiderationCashPaid 2,755,000cli_BusinessAcquisitionContingentConsiderationCashPaid                  
General and administrative 23,950,000us-gaap_GeneralAndAdministrativeExpense 12,665,000us-gaap_GeneralAndAdministrativeExpense 13,673,000us-gaap_GeneralAndAdministrativeExpense 22,881,000us-gaap_GeneralAndAdministrativeExpense 10,447,000us-gaap_GeneralAndAdministrativeExpense 12,151,000us-gaap_GeneralAndAdministrativeExpense 13,111,000us-gaap_GeneralAndAdministrativeExpense 11,973,000us-gaap_GeneralAndAdministrativeExpense 73,169,000us-gaap_GeneralAndAdministrativeExpense 47,682,000us-gaap_GeneralAndAdministrativeExpense 47,664,000us-gaap_GeneralAndAdministrativeExpense                
Accounts payable, accrued expenses and other liabilities 126,971,000us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent       121,286,000us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent       126,971,000us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent 121,286,000us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent                  
Minimum [Member]                                      
Commitments And Contingencies [Line Items]                                      
Percentage of interest in venture 7.50%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		              7.50%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_RangeAxis
= us-gaap_MinimumMember 		                   
Roseland Partners, L.L.C. [Member]                                      
Commitments And Contingencies [Line Items]                                      
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 		         
Business acquisition, contingent cash payment                                     15,600,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
General and administrative                 1,100,000us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember 		                   
Accounts payable, accrued expenses and other liabilities 1,000,000us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember 		              1,000,000us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember 		                   
Roseland Partners, L.L.C. [Member] | Messr Goldberg [Member]                                      
Commitments And Contingencies [Line Items]                                      
Consulting period                 1 year                    
Roseland Partners, L.L.C. [Member] | Messr Klatt And Messr Goldberg [Member]                                      
Commitments And Contingencies [Line Items]                                      
Period for continuation of health insurance                 1 year                    
Roseland Partners, L.L.C. [Member] | Messr Tycher [Member] | Minimum [Member]                                      
Commitments And Contingencies [Line Items]                                      
Percentage of interest in venture 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurTycherMember 		              50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurTycherMember 		                   
Roseland Partners, L.L.C. [Member] | Scenario, Forecast [Member] | Messr Goldberg [Member]                                      
Commitments And Contingencies [Line Items]                                      
Consulting payment                             400,000us-gaap_ProfessionalFees
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurGoldbergMember 		       
Number of installments                             4cli_NumberOfInstallments
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurGoldbergMember 		       
Roseland Partners, L.L.C. [Member] | Scenario, Forecast [Member] | Messr Klatt And Messr Goldberg [Member]                                      
Commitments And Contingencies [Line Items]                                      
Severance benefits                               500,000us-gaap_SeveranceCosts1
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurKlattAndMessieurGoldbergMember 		750,000us-gaap_SeveranceCosts1
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurKlattAndMessieurGoldbergMember 		   
Roseland Partners, L.L.C. [Member] | Obtaining Of Tax Credits/Grants [Member]                                      
Commitments And Contingencies [Line Items]                                      
Earn out paid                                   1,000,000cli_BusinessAcquisitionContingentConsiderationCashPaid
/ us-gaap_BusinessAcquisitionAxis
= cli_RoselandPartnersLLCMember
/ us-gaap_ContingentConsiderationByTypeAxis
= cli_ObtainingOfTaxCreditsGrantsMember 		 
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
Roseland Partners, L.L.C. [Member] | Obtaining Of Tax Credits/Grants [Member] | Scenario, Forecast [Member]                                      
Commitments And Contingencies [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 		                   
[1] Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.