Annual report pursuant to Section 13 and 15(d)

Investments In Unconsolidated Joint Ventures (Crystal House Apartments Investors LLC) (Narrative) (Details)

v2.4.1.9
Investments In Unconsolidated Joint Ventures (Crystal House Apartments Investors LLC) (Narrative) (Details) (USD $)
 0 Months Ended 12 Months Ended
Mar. 20, 2013
Dec. 31, 2014
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Mar. 20, 2013
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Schedule of Equity Method Investments [Line Items]      
Percentage of interest in venture      [1]  
Internal rate of return   9.00%cli_InternalRateOfReturn  
Mortgage loans, carrying amount   $ 1,673,364,000us-gaap_MortgageLoansOnRealEstateCarryingAmountOfMortgages  
Parent Company [Member]      
Schedule of Equity Method Investments [Line Items]      
Percentage of capital event cash flows distributed   50.00%cli_PercentageOfCapitalEventCashFlowsDistributed
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember 		 
UBS Global Asset Management [Member]      
Schedule of Equity Method Investments [Line Items]      
Percentage of capital event cash flows distributed   50.00%cli_PercentageOfCapitalEventCashFlowsDistributed
/ dei_LegalEntityAxis
= cli_UBSGlobalAssetManagementMember 		 
Crystal House Apartments Investors LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Number of units 828us-gaap_NumberOfUnitsInRealEstateProperty
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		828us-gaap_NumberOfUnitsInRealEstateProperty
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		[2] 828us-gaap_NumberOfUnitsInRealEstateProperty
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
Venture property acquisition cost 262,500,000cli_VenturePropertyAcquisitionCost
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		   
Percentage of interest in venture 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		[1],[2] 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
Percentage of interest in developable land 50.00%cli_PercentageOfInterestInDevelopableLand
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		50.00%cli_PercentageOfInterestInDevelopableLand
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		50.00%cli_PercentageOfInterestInDevelopableLand
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
Business acquisition, cash paid 30,200,000us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		   
Number of units available for development 295cli_NumberOfUnitsAvailableForDevelopment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		295cli_NumberOfUnitsAvailableForDevelopment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		295cli_NumberOfUnitsAvailableForDevelopment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
Number of approved units available for development 252cli_NumberOfApprovedUnitsAvailableForDevelopment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		252cli_NumberOfApprovedUnitsAvailableForDevelopment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		252cli_NumberOfApprovedUnitsAvailableForDevelopment
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
Interest rate   3.17%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		[2]  
Mortgage loan, maturity date   04/01/20 [2]  
Initial term of interest only payments   5 years  
Mortgage loan, maturity period   30 years  
Holding and distribution pattern under operating agreement   In general, the operating agreement of CHAI provides that net operating cash flows are distributed to the members in accordance with ownership percentages. Net cash flows from a capital event are distributed first to the members in accordance with ownership percentages until they receive a nine percent IRR, as defined, with any excess distributed 50 percent to the Company and 50 percent to UBS.  
Mortgage loans, carrying amount   $ 165,000,000us-gaap_MortgageLoansOnRealEstateCarryingAmountOfMortgages
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		[2]  
[1] Company's effective ownership % represents the Company's entitlement to residual distributions after payments of priority returns, where applicable.
[2] The Company also owns a 50 percent interest in a vacant land parcel to accommodate the development of approximately 295 additional units of which 252 are currently approved.