Annual report pursuant to Section 13 and 15(d)

Deferred Charges, Goodwill And Other Assets (Schedule Of Deferred Charges, Goodwill And Other Assets) (Details)

v2.4.1.9
Deferred Charges, Goodwill And Other Assets (Schedule Of Deferred Charges, Goodwill And Other Assets) (Details) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Deferred Charges, Goodwill And Other Assets [Line Items]      
Deferred leasing costs $ 239,138,000us-gaap_DeferredCostsLeasingGross $ 258,648,000us-gaap_DeferredCostsLeasingGross  
Deferred financing costs 24,042,000us-gaap_DeferredFinanceCostsGross 25,366,000us-gaap_DeferredFinanceCostsGross  
Deferred charges, gross 263,180,000cli_DeferredCostsGross 284,014,000cli_DeferredCostsGross  
Accumulated amortization (122,358,000)cli_AccumulatedAmortizationLeasingAndFinancingCosts (131,669,000)cli_AccumulatedAmortizationLeasingAndFinancingCosts  
Deferred charges, net 140,822,000us-gaap_DeferredCosts 152,345,000us-gaap_DeferredCosts  
Notes receivable 21,491,000us-gaap_LoansAndLeasesReceivableNetReportedAmount [1] 21,986,000us-gaap_LoansAndLeasesReceivableNetReportedAmount [1]  
In-place lease values, related intangible and other assets, net 6,565,000us-gaap_FiniteLivedIntangibleAssetAcquiredInPlaceLeases 13,659,000us-gaap_FiniteLivedIntangibleAssetAcquiredInPlaceLeases  
Goodwill 2,945,000us-gaap_Goodwill 2,945,000us-gaap_Goodwill  
Prepaid expenses and other assets, net 32,827,000us-gaap_PrepaidExpenseAndOtherAssets 27,584,000us-gaap_PrepaidExpenseAndOtherAssets  
Total deferred charges, goodwill and other assets 204,650,000us-gaap_OtherAssets 218,519,000us-gaap_OtherAssets  
Lease revenue 516,727,000us-gaap_OperatingLeasesIncomeStatementLeaseRevenue 540,165,000us-gaap_OperatingLeasesIncomeStatementLeaseRevenue 535,822,000us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
Acquired Above And Below Market Lease Intangibles [Member]      
Deferred Charges, Goodwill And Other Assets [Line Items]      
Lease revenue 700,000us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= cli_AcquiredAboveAndBelowMarketLeaseIntangiblesMember 		1,500,000us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= cli_AcquiredAboveAndBelowMarketLeaseIntangiblesMember 		1,400,000us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= cli_AcquiredAboveAndBelowMarketLeaseIntangiblesMember
Mortgage Receivable [Member]      
Deferred Charges, Goodwill And Other Assets [Line Items]      
Notes receivable 10,400,000us-gaap_LoansAndLeasesReceivableNetReportedAmount
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_MortgageReceivablesMember 		   
Spread over LIBOR 6.00%cli_MortgageLoansOnRealEstateBasisSpreadOverVariableInterestRate
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_MortgageReceivablesMember 		   
8% Notes Receivable [Member]      
Deferred Charges, Goodwill And Other Assets [Line Items]      
Notes receivable 7,800,000us-gaap_LoansAndLeasesReceivableNetReportedAmount
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= cli_EightPercentNotesReceivableMember 		   
Interest rate 8.00%us-gaap_MortgageLoansOnRealEstateInterestRate
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= cli_EightPercentNotesReceivableMember 		   
Interest-Free Notes Receivable [Member]      
Deferred Charges, Goodwill And Other Assets [Line Items]      
Notes receivable $ 3,300,000us-gaap_LoansAndLeasesReceivableNetReportedAmount
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= cli_InterestFreeNotesReceivableMember 		   
[1] Includes as of December 31, 2014: a mortgage receivable for $10.4 million which bears interest at LIBOR plus six percent and matures in August 2015; a note receivable for $7.8 million which bears interest at eight percent and matures in October 2017; and an interest-free note receivable with a net present value of $3.3 million and matures in April 2023. The Company believes these balances are fully collectable.