Quarterly report pursuant to Section 13 or 15(d)

Mortgages, Loans Payable And Other Obligations (Narrative) (Details)

v2.4.1.9
Mortgages, Loans Payable And Other Obligations (Narrative) (Details) (USD $)
 3 Months Ended
Mar. 31, 2015
property
Mar. 31, 2014
Dec. 31, 2014
Debt Instrument [Line Items]      
Number of properties with encumbered company mortgages 28cli_NumberOfPropertiesWithEncumberedCompanyMortgages    
Book value of encumbered properties $ 968,000,000cli_MortgagePropertyCarryingValue    
Cash paid for interest 25,922,000us-gaap_InterestPaid 36,119,000us-gaap_InterestPaid  
Interest capitalized 3,607,000us-gaap_InterestCostsCapitalized 3,141,000us-gaap_InterestCostsCapitalized  
Total indebtedness 2,107,572,000us-gaap_LongTermDebt   2,088,654,000us-gaap_LongTermDebt
Total indebtedness, weighted average interest rate 5.65%us-gaap_LongtermDebtWeightedAverageInterestRate   5.64%us-gaap_LongtermDebtWeightedAverageInterestRate
Revolving Credit Facility Borrowing And Other Variable Rate Mortgage Debt [Member]      
Debt Instrument [Line Items]      
Total indebtedness 179,795,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember 		  159,860,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember
Total indebtedness, weighted average interest rate 3.33%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember 		  3.83%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember
Fixed Rate Debt And Other Obligations [Member]      
Debt Instrument [Line Items]      
Total indebtedness 1,927,777,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember 		  1,928,794,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember
Total indebtedness, weighted average interest rate 5.87%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember 		  5.79%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember
Unconsolidated Joint Venture [Member]      
Debt Instrument [Line Items]      
Interest capitalized $ 1,256,000us-gaap_InterestCostsCapitalized
/ dei_LegalEntityAxis
= us-gaap_CorporateJointVentureMember 		$ 918,000us-gaap_InterestCostsCapitalized
/ dei_LegalEntityAxis
= us-gaap_CorporateJointVentureMember